Pathological Response to Neoadjuvant Therapy in Breast Cancer Patients and Its Relationship with Survival: A Retrospective Cohort Study

Pathological Response to Neoadjuvant Therapy in Breast Cancer Patients and Its Relationship with Survival: A Retrospective Cohort Study | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Pathological Response to Neoadjuvant Therapy in Breast Cancer Patients and Its Relationship with Survival: A Retrospective Cohort Study Sara Loaiza-Osorio, Ana María Caicedo, Elsa María Vásquez, Néstor Llinás Quintero, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5477374/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Introduction: Breast cancer is the most common cancer among women worldwide. Neoadjuvant therapy (NAC) aims to reduce tumor size before surgery and assess the tumor's biological response to treatment. Pathological complete response (pCR) is an important marker of oncological outcomes, but its evaluation in the Colombian population is limited. This study aimed to evaluate pCR and its relationship with overall survival in breast cancer patients who received NAC at a hospital in Medellín. Methodology: This is a retrospective cohort observational study conducted at Clínica Vida, Medellín, between 2017 and 2023, including 1,008 breast cancer patients treated with NAC. Sociodemographic, histological, and treatment variables were evaluated. Bivariate analyses and the Kaplan-Meier test were used to assess survival. Results A total of 36.2% of the patients achieved pCR, which was associated with better overall survival (95.1% vs. 91.1%). Factors associated with pCR included younger age, higher histological grade, elevated Ki67, negative hormone receptors, and lower lymph node involvement. The use of anthracycline-based chemotherapy, taxanes, and Trastuzumab was more common in pCR. Most patients with pCR underwent conservative surgery and sentinel lymph node biopsy. Conclusions Factors such as tumor biology and therapeutic regimen significantly influence the likelihood of achieving pCR and improving long-term survival. This highlights the importance of personalizing NAC in breast cancer, guided by specific biological characteristics of the tumor to optimize clinical outcomes. Breast cancer neoadjuvant therapy pathological complete response survival retrospective cohort study Figures Figure 1 Introduction Breast cancer is the most common type of cancer among women worldwide, with a global incidence of 11.5% ( 1 , 2 ). In Colombia, according to Globocan 2022 data, the incidence reaches 17.9%, making it the leading cause of death in women, with a mortality rate of 17.5% ( 3 ). Breast tumors are classified on the basis of their expression of tumor markers and display heterogeneous biological behavior, leading to varying responses to specific oncologic therapies( 4 ). Neoadjuvant therapy (NAC) is defined as systemic treatment administered before primary surgery in cancer patients; one of its goals is to reduce the tumor size to facilitate surgical resection and increase the likelihood of conservative surgical management. In the context of breast cancer, neoadjuvant therapy aims to decrease tumor volume and allows for the assessment of the biological response of the tumor to the treatment ( 5 ), providing relevant prognostic information and potentially guiding subsequent therapeutic decisions without impacting overall survival or disease-free survival compared with women who do not receive it ( 6 , 7 ). Currently, the definition of pathological complete response (pCR) is not fully standardized ( 8 ); it is typically considered the absence of residual tumor cells in breast tissue after the administration of neoadjuvant systemic therapy. Other authors ( 9 , 10 ) also reported the absence of tumor cells in axillary lymph nodes. Evidence shows that pCR is a robust predictive marker of long-term oncologic outcomes ( 11 ). A meta-analysis by Cortázar et al. revealed that patients who achieved pCR have better survival and that molecular subtypes (Luminal A, Luminal B, HER2+, and triple-negative) significantly influence the pathological response ( 12 ). In Colombia, data on the response of breast cancer patients to NAC therapy are limited. A literature search on pCR after NAC in the PUBMED, EMBASE, ClinicalKey, Dynamed, Medline, and Scopus databases identified only five observational retrospective cohort studies evaluating tumor response to neoadjuvant therapy ( 13 – 17 ). However, there remains a gap in the local literature regarding clinicopathological factors associated with a higher pCR rate in our population. Materials and methods Aim This study aimed to evaluate the pathological response of breast cancer patients who received neoadjuvant systemic therapy at a high-complexity hospital in Medellín, Colombia, as well as its impact on overall survival and differences according to patients’ clinical treatment factors. Design and Setting A retrospective cohort observational study was conducted on breast cancer patients treated with neoadjuvant therapy at Clínica Vida, Medellín, Colombia. The follow-up period spanned from January 2017 to the event of interest, the last clinical evaluation, or censoring. The patients included were those treated between January 1, 2017, and December 31, 2023. Data collection was carried out between January and May 2024. Participants Records of all breast cancer patients treated with neoadjuvant therapy at Clínica Vida, Medellín, between January 2017 and December 2023 were included. Records with more than 10% incomplete or missing data were excluded. Diagnostic Methodology Disease staging followed the guidelines of the 8th edition of the American Joint Committee on Cancer (AJCC), with clinical evaluation by mastologists and oncologists. In all cases, the diagnosis was confirmed through core needle biopsy, including histologic evaluation, hormone receptor status (estrogen receptor [ER] and progesterone receptor [PR]), HER2 status (measured by immunohistochemistry), differentiation grade, and Ki67 level (%). Tumors were phenotypically classified into luminal A, luminal B, HER2, and triple-negative subtypes. Variables and Data Sources : Sociodemographic variables, histological tumor characteristics (histologic grade, hormone receptor status, Ki67, HER2), variables related to the neoadjuvant response (tumor size before and after neoadjuvant therapy, chemotherapy regimen used, and imaging and pathological response), and variables related to adjuvant therapy (type of surgery, need for radiotherapy) were analyzed. Pathologic complete response (pCR) was defined as the absence of tumor cells in both the breast and axillary lymph nodes in the postneoadjuvant surgical specimen, as determined by expert oncologic pathologists at the institution. The residual cancer burden (RCB) was calculated for each sample according to the guidelines established by the MD Anderson Cancer Center and categorized into four groups on the basis of the resulting index: RCB 0, RCB I, RCB II, and RCB III. Overall survival was defined as the percentage of patients alive after five years, as assessed from January 2017 to December 2023. Bias control : To control for selection and information bias, the following measures were taken: ( 1 ) thorough review of the database to ensure compliance with the inclusion and exclusion criteria and ( 2 ) verification of all clinical records by trained and standardized personnel, ensuring uniform data extraction according to the same criteria. Sample size All patients treated between January 2017 and December 2023 were included. Statistical analysis Quantitative variables are presented as the means and standard deviations or interquartile ranges, as appropriate. Categorical variables are expressed as absolute values or percentages. The Kolmogorov‒Smirnov test was used to assess the normality of distributions. Bivariate analyses were conducted via t tests, Mann‒Whitney U tests, and chi‒square tests, depending on the data type. A p value ≤ 0.05 was considered statistically significant. Differences in overall survival were assessed via the Kaplan‒Meier method and compared via the log-rank test. All analyses were conducted via Stata software, version 12 (StataCorp, College Station, TX, USA). This study received approval from the Institutional Review Board of Clínica Vida and was conducted in accordance with the Declaration of Helsinki. Results A total of 1,008 records of operable breast cancer patients treated with neoadjuvant chemotherapy were included. The median age was 54 years, and the majority of patients belonged to the contributory health regime. The most prevalent histological subtype was luminal B, accounting for 44%, followed by triple-negative (22%), luminal A (19.15%), and HER2+ (14.2%). Among the patients, 77.1% (n = 778) received an anthracycline and taxane-based chemotherapy regimen, and 22% also received anti-HER2 therapy. A complete treatment regimen was administered to 99.4% of the patients. In Table 1 , the clinical and pathological differences between the groups with a pathological complete response (pCR, n = 365) and those without a pathological complete response (no-pCR, n = 640) were analyzed. The median age was significantly lower in the pCR group (52.4 years) than in the no-pCR group (56 years) (p < 0.0001). In terms of histological grade, Grade 3 tumors were more common in the pCR group (63.8% vs. 44.1%), whereas Grade 2 and Grade 1 tumors were more common in the no-pCR group (45% and 10.9%, respectively) (p < 0.0001). For hormone receptors, the pCR group presented a greater percentage of hormone receptor-negative tumors (50.7% vs. 26.4%) than did the no-pCR group (p < 0.0001). The Ki67 index, an indicator of cellular proliferation, was also significantly greater in the pCR group (median 50 vs. 35; p < 0.0001). No significant differences in tumor size at diagnosis were observed between the two groups (median of 21 mm in the pCR group vs. 23 mm in the no-pCR group; p = 0.333). Finally, lymph node involvement at diagnosis was significantly lower in the pCR group (32.3% vs. 69.8% in the no-pCR group; p < 0.0001). ( Table 1 ). Table 1 Comparison of clinical and pathological differences between groups with and without pathological complete response (pCR) Characteristics pCR (n = 365) No-pCR (n = 640) P Value Median Age 52.4 (16.71) 56 (19.42) < 0.0001 Histological Grade Grade 1 19 (5.2%) 70 (10.9%) < 0.0001 Grade 2 113 (31%) 288 (45%) Grade 3 233 (63.8%) 282 (44.1%) Hormone Receptors (%) Positive 180 (49.3%) 471 (73.6%) < 0.0001 Negative 185 (50.7%) 169 (26.4%) Ki67 Median (IQR) 50 (30–80) 35 (20–60) < 0.0001 Histological Subtype < 0.0001 Ductal 339 (92.9%) 578 (90.3%) Lobular 10 (2.7%) 36 (5.6%) Other 16 (4.4%) 26 (4.1%) Tumor Size (mm) at Diagnosis 21 (27) 23 (26) 0.333 Lymph Node Involvement at Diagnosis < 0.0001 Yes 118 (32.3%) 447 (69.8%) No 247 (67.7%) 192 (30%) As shown in Table 2 , treatment differences between patients who achieved pCR and those who did not achieve pCR were analyzed. The anthracycline and taxane-based neoadjuvant regimens were the most commonly used regimens in both groups and were more common in the no-pCR group (83.4% vs. 65.2% in pCR). Conversely, the use of trastuzumab alongside an anthracycline and taxane regimen was significantly greater in the pCR group (34.2% vs. 15%; p < 0.0001). With respect to the type of surgery, quadrantectomy with sentinel lymph node biopsy was more common in the pCR group (47.9% vs. 32.3%), whereas modified radical mastectomy was more common in the no-pCR group (38% vs. 25.5%) (p < 0.0001). Adjuvant hormone therapy with tamoxifen was similar between the two groups (53.4% in the pCR group vs. 57.5% in the no-pCR group), but aromatase inhibitors were more commonly used in the no-pCR group (20.9% vs. 8.5%; p < 0.0001). No significant differences were found in the use of adjuvant radiotherapy between the groups (p = 0.246). (Table 2 ). Table 2 Differences between groups with and without pathological complete response (pCR) Type of Treatment pCR No-pCR P Value Neoadjuvant Regimen < 0.0001 Based on Anthracyclines 0 (0%) 4 (0.6%) Based on Anthracyclines and Taxanes 238 (65.2%) 534 (83.4%) Based on Taxanes Alone 2 (0.5%) 6 (0.9%) Anthracyclines + Taxanes + Trastuzumab 125 (34.2%) 96 (15%) Type of Surgery < 0.0001 Mastectomy + Axillary Dissection 93 (25.5%) 243 (38%) Mastectomy + Sentinel Node Biopsy 34 (9.3%) 58 (9.1%) Quadrantectomy + Sentinel Node Biopsy 175 (47.9%) 207 (32.3%) Quadrantectomy + Axillary Dissection 63 (17.3%) 132 (20.6%) Adjuvant Hormone Therapy < 0.0001 Tamoxifen 195 (53.4%) 368 (57.5%) Aromatase Inhibitors 31 (8.5%) 134 (20.9%) None 139 (38.1%) 137 (21.4%) Adjuvant Radiotherapy 0.246 Yes 355 (97.3%) 628 (98.1%) No 10 (2.7%) 12 (1.9%) Patient survival was assessed via the Kaplan‒Meier method (Fig. 1 ), which revealed significant differences in cumulative survival between patients with and without pathological complete response (pCR) over a follow-up period of up to 80 months. This graph indicated that patients who achieved a pathological complete response (pCR) had significantly better survival than those who did not. As the follow-up period increased, the separation between the curves of the two groups became more evident, suggesting a significant difference in survival outcomes, according to the log-rank test (p = 0.002). The "complete" group curve (in green) remained higher and more stable than the "no" group curve (in blue), suggesting that pCR is associated with better long-term survival. Finally, the behavior of patients with lymph node involvement in the initial stage was evaluated. In total, 56.8% (n = 568) presented with lymph node involvement at the time of diagnosis. Among these patients, 76.4% continued to have a tumor burden in the axillary lymph nodes following neoadjuvant treatment. In the remaining group (23.5%), no lymph node involvement was found in the postsurgical pathological analysis. Among these patients, 53.7% underwent axillary lymph node dissection. Discussion A pathological complete response was observed in 36.2% (365) of the evaluated patients. The remaining 63.5% (640) did not achieve a pathological response or achieved only a partial response. Younger age, higher histologic grade tumors, an elevated Ki67 index, negative hormone receptor expression, and lower lymph node involvement at diagnosis were significantly associated with a greater likelihood of achieving pathological complete response (pCR) after neoadjuvant therapy in breast cancer patients. These results are consistent with those of previous studies, which demonstrated that these clinicopathological factors are important predictors of pCR, which is associated with better long-term outcomes, including overall survival. ( 12 , 18 ). Studies such as that by Cortázar et al. ( 12 ) have established that pCR is a robust prognostic marker, especially in aggressive breast cancer subgroups, such as HER2-positive and triple-negative patients. Our finding that a higher Ki67 index, younger age, and hormone receptor negativity are associated with higher pCR rates aligns with these results, highlighting the importance of a tumor’s proliferative and molecular profile as predictors of response to neoadjuvant chemotherapy. Regarding the type of neoadjuvant treatment, our data revealed that patients who achieved pCR tended to receive more intensive chemotherapy combinations, such as anthracycline, taxane, and trastuzumab regimens. This approach is consistent with the results of the NEOSPHERE and TRYPHAENA trials, which have demonstrated the efficacy of intensive chemotherapy regimens in increasing pCR, particularly in HER2-positive tumors ( 18 , 19 ). Additionally, our results indicate that patients who achieved pCR had a greater frequency of conservative surgeries, such as quadrantectomy, which is consistent with the literature suggesting that achieving pCR enables less radical surgical options ( 8 ). On the other hand, patients without pCR in our study had greater use of aromatase inhibitors and a greater frequency of mastectomy with axillary lymph node dissection. This treatment pattern may reflect both tumor biology, with lower sensitivity to chemotherapy, and the clinical preference for opting for more aggressive and exhaustive treatments in patients with residual disease after neoadjuvant therapy, as described by Masuda et al. in their analyses of triple-negative breast cancer treatment ( 20 ). Long-term survival is also affected by pathological complete response. Kaplan‒Meier curves demonstrated that patients who achieved pCR had better overall survival than did those who did not, underscoring the importance of achieving pCR in the context of breast cancer treatment. This finding is supported by studies such as those by von Minckwitz et al., which showed that pCR is consistently associated with better disease-free and overall survival rates across a variety of molecular breast cancer subtypes ( 8 ). The results of this study should be interpreted in light of the following limitations. First, this study is retrospective and based on the clinical records of a single center, which could limit the generalizability of the findings. Second, although measures were taken to reduce selection and information bias, these measures cannot be entirely ruled out. Future multicenter and prospective studies would be useful to validate these findings and further explore the interactions between different clinicopathological factors and treatment response. Conclusion These results demonstrate that factors such as tumor biology and treatment regimens significantly influence the likelihood of achieving pCR and, consequently, long-term survival. This highlights the importance of personalizing neoadjuvant treatment for breast cancer, guided by specific biological characteristics of the tumor, to optimize clinical outcomes. Abbreviations NAC : Neoadjuvant Chemotherapy pCR : Pathological Complete Response ER : Estrogen Receptor PR : Progesterone Receptor HER2 : Human Epidermal Growth Factor Receptor 2 AJCC : American Joint Committee on Cancer RCB : Residual Cancer Burden IQR : Interquartile Range TX : Texas USA : United States of America Declarations Ethics Approval and Consent to Participate: This study was approved by the ethics committee of Clínica Vida, Medellín, and Universidad CES. Documents are attached in other supplements. The expedited approval document for the project CIP 0159-10-2022, "Evaluation of Overall Survival and Pathological Response in Patients Who Received Neoadjuvant Therapy with a Diagnosis of Breast Cancer at a Hospital in the City of Medellín” CTI AE 012 PI. Availability of Data and Materials: All data generated or analysed during this study are included in this published article [and its supplementary information files]. Competing Interests: None. Funding: Not applicable. Authors' Contributions: SL developed the study protocol, participated in data collection, and contributed to writing the article; AMC participated in data collection and contributed to writing the article; EMV performed the statistical analysis and reviewed the article's writing; AMN reviewed the study protocol and contributed to writing the article; NL contributed to writing the article. All authors read and approved the final manuscript. Acknowledgments: Clara del Pilar Osorio, for your help throughout the manuscript construction process Authors' Information: Sara Loaiza is a gynecologist and obstetrician and completed a subspecialty in mastology. She has a special interest in research and public health. References Terry MB, Colditz GA. Epidemiology and Risk Factors for Breast Cancer: 21st Century Advances, Gaps to Address through Interdisciplinary Science. Cold Spring Harb Perspect Med. 2023;13(9):a041317. Bravo LE, Muñoz N. Epidemiology of cancer in Colombia. Colomb Med. 2018;49(1):9–12. Instituto Nacional de Cancerología. Cáncer en cifras. 2022. pp. 1–2 Cáncer en cifras. Gao JJ, Swain SM. Luminal A Breast Cancer and Molecular Assays: A Review. Oncologist. 2018;23(5):556–65. National Cancer Institute. Definition of neoadjuvant therapy. 2024. pp. 1–1 Definition of neoadjuvant therapy. Wolmark N, Wang J, Mamounas E, Bryant J, Fisher B. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-5477374","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":379962854,"identity":"3b796b11-7672-4fa5-b644-cb93cd77c8f7","order_by":0,"name":"Sara Loaiza-Osorio","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA5UlEQVRIie3PsQrCMBCA4QsHcTl0jajkFQpdnPRVWoS6uLkoDiKFdBH6NtnFwaXuBRej4KyDoJupk1NbN8H8Q27JRy4ALtevdgQgALayE6hZiwRvgrFXEF6X2BpKFKOSyGRvrsFs0JXJRs3vk0GXA5pTXkK8bOyLIBsRW4fq0NMjuxj3/UkZgQhEqJAQLGlrtIR4p4zI9IKPUC2Jt4yatvWymkAecfvKlsie7Ka31cTLL7wfZDsSwsQdpnfEseIvMo0wv84WQ5mOze2pF8NWIzbn0sU+Q3qfda8Xscc3t10ul+tvegGD4UEXRUBMcAAAAABJRU5ErkJggg==","orcid":"","institution":"CES University","correspondingAuthor":true,"prefix":"","firstName":"Sara","middleName":"","lastName":"Loaiza-Osorio","suffix":""},{"id":379962856,"identity":"fdfc3771-af65-4aee-bc43-680d0ad15b4a","order_by":1,"name":"Ana María Caicedo","email":"","orcid":"","institution":"Universidad de Antioquia","correspondingAuthor":false,"prefix":"","firstName":"Ana","middleName":"María","lastName":"Caicedo","suffix":""},{"id":379962857,"identity":"e66d389c-c2eb-49d9-ac09-1c78cf5cc22d","order_by":2,"name":"Elsa María Vásquez","email":"","orcid":"","institution":"CES University","correspondingAuthor":false,"prefix":"","firstName":"Elsa","middleName":"María","lastName":"Vásquez","suffix":""},{"id":379962858,"identity":"3587c4ed-90d9-40a0-9ec0-2c6e6155e7e2","order_by":3,"name":"Néstor Llinás Quintero","email":"","orcid":"","institution":"Clínica VIDA","correspondingAuthor":false,"prefix":"","firstName":"Néstor","middleName":"Llinás","lastName":"Quintero","suffix":""},{"id":379962859,"identity":"e21ff861-57f0-4b1b-88d0-cdfc177fc052","order_by":4,"name":"Ana María Naranjo","email":"","orcid":"","institution":"Clínica VIDA","correspondingAuthor":false,"prefix":"","firstName":"Ana","middleName":"María","lastName":"Naranjo","suffix":""}],"badges":[],"createdAt":"2024-11-18 15:38:30","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-5477374/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-5477374/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":71880100,"identity":"9fbff4e1-f539-4efc-a7a6-2773824acd24","added_by":"auto","created_at":"2024-12-19 11:26:19","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":37833,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eKaplan‒Meier survival curves for patients with and without pCR\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"Graph1.png","url":"https://assets-eu.researchsquare.com/files/rs-5477374/v1/637ef9560191280575b26e0c.png"},{"id":96914585,"identity":"6b4a9fae-8b64-4122-a076-5c6eeadc5531","added_by":"auto","created_at":"2025-11-27 14:06:06","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":755133,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5477374/v1/cfad19db-cf71-4ee0-ae0a-5f2ae158da80.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Pathological Response to Neoadjuvant Therapy in Breast Cancer Patients and Its Relationship with Survival: A Retrospective Cohort Study","fulltext":[{"header":"Introduction","content":"\u003cp\u003eBreast cancer is the most common type of cancer among women worldwide, with a global incidence of 11.5% (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e). In Colombia, according to Globocan 2022 data, the incidence reaches 17.9%, making it the leading cause of death in women, with a mortality rate of 17.5% (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e). Breast tumors are classified on the basis of their expression of tumor markers and display heterogeneous biological behavior, leading to varying responses to specific oncologic therapies(\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eNeoadjuvant therapy (NAC) is defined as systemic treatment administered before primary surgery in cancer patients; one of its goals is to reduce the tumor size to facilitate surgical resection and increase the likelihood of conservative surgical management. In the context of breast cancer, neoadjuvant therapy aims to decrease tumor volume and allows for the assessment of the biological response of the tumor to the treatment (\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e), providing relevant prognostic information and potentially guiding subsequent therapeutic decisions without impacting overall survival or disease-free survival compared with women who do not receive it (\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eCurrently, the definition of pathological complete response (pCR) is not fully standardized (\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e); it is typically considered the absence of residual tumor cells in breast tissue after the administration of neoadjuvant systemic therapy. Other authors (\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e) also reported the absence of tumor cells in axillary lymph nodes. Evidence shows that pCR is a robust predictive marker of long-term oncologic outcomes (\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e). A meta-analysis by Cort\u0026aacute;zar et al. revealed that patients who achieved pCR have better survival and that molecular subtypes (Luminal A, Luminal B, HER2+, and triple-negative) significantly influence the pathological response (\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIn Colombia, data on the response of breast cancer patients to NAC therapy are limited. A literature search on pCR after NAC in the PUBMED, EMBASE, ClinicalKey, Dynamed, Medline, and Scopus databases identified only five observational retrospective cohort studies evaluating tumor response to neoadjuvant therapy (\u003cspan additionalcitationids=\"CR14 CR15 CR16\" citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e). However, there remains a gap in the local literature regarding clinicopathological factors associated with a higher pCR rate in our population.\u003c/p\u003e"},{"header":"Materials and methods","content":"\u003cp\u003e \u003cstrong\u003eAim\u003c/strong\u003e \u003cp\u003e This study aimed to evaluate the pathological response of breast cancer patients who received neoadjuvant systemic therapy at a high-complexity hospital in Medell\u0026iacute;n, Colombia, as well as its impact on overall survival and differences according to patients\u0026rsquo; clinical treatment factors.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eDesign and Setting\u003c/strong\u003e \u003cp\u003eA retrospective cohort observational study was conducted on breast cancer patients treated with neoadjuvant therapy at Cl\u0026iacute;nica Vida, Medell\u0026iacute;n, Colombia. The follow-up period spanned from January 2017 to the event of interest, the last clinical evaluation, or censoring. The patients included were those treated between January 1, 2017, and December 31, 2023. Data collection was carried out between January and May 2024.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eParticipants\u003c/strong\u003e \u003cp\u003eRecords of all breast cancer patients treated with neoadjuvant therapy at Cl\u0026iacute;nica Vida, Medell\u0026iacute;n, between January 2017 and December 2023 were included. Records with more than 10% incomplete or missing data were excluded.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eDiagnostic Methodology\u003c/strong\u003e \u003cp\u003e Disease staging followed the guidelines of the 8th edition of the American Joint Committee on Cancer (AJCC), with clinical evaluation by mastologists and oncologists. In all cases, the diagnosis was confirmed through core needle biopsy, including histologic evaluation, hormone receptor status (estrogen receptor [ER] and progesterone receptor [PR]), HER2 status (measured by immunohistochemistry), differentiation grade, and Ki67 level (%). Tumors were phenotypically classified into luminal A, luminal B, HER2, and triple-negative subtypes.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e\u003cb\u003eVariables and Data Sources\u003c/b\u003e: Sociodemographic variables, histological tumor characteristics (histologic grade, hormone receptor status, Ki67, HER2), variables related to the neoadjuvant response (tumor size before and after neoadjuvant therapy, chemotherapy regimen used, and imaging and pathological response), and variables related to adjuvant therapy (type of surgery, need for radiotherapy) were analyzed. Pathologic complete response (pCR) was defined as the absence of tumor cells in both the breast and axillary lymph nodes in the postneoadjuvant surgical specimen, as determined by expert oncologic pathologists at the institution. The residual cancer burden (RCB) was calculated for each sample according to the guidelines established by the MD Anderson Cancer Center and categorized into four groups on the basis of the resulting index: RCB 0, RCB I, RCB II, and RCB III. Overall survival was defined as the percentage of patients alive after five years, as assessed from January 2017 to December 2023.\u003c/p\u003e \u003cp\u003e \u003cb\u003eBias control\u003c/b\u003e: To control for selection and information bias, the following measures were taken: (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e) thorough review of the database to ensure compliance with the inclusion and exclusion criteria and (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e) verification of all clinical records by trained and standardized personnel, ensuring uniform data extraction according to the same criteria.\u003c/p\u003e \u003cp\u003e \u003cstrong\u003eSample size\u003c/strong\u003e \u003cp\u003eAll patients treated between January 2017 and December 2023 were included.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eStatistical analysis\u003c/strong\u003e \u003cp\u003eQuantitative variables are presented as the means and standard deviations or interquartile ranges, as appropriate. Categorical variables are expressed as absolute values or percentages. The Kolmogorov‒Smirnov test was used to assess the normality of distributions. Bivariate analyses were conducted via t tests, Mann‒Whitney U tests, and chi‒square tests, depending on the data type. A p value\u0026thinsp;\u0026le;\u0026thinsp;0.05 was considered statistically significant.\u003c/p\u003e \u003c/p\u003e \u003cp\u003eDifferences in overall survival were assessed via the Kaplan‒Meier method and compared via the log-rank test. All analyses were conducted via Stata software, version 12 (StataCorp, College Station, TX, USA). This study received approval from the Institutional Review Board of Cl\u0026iacute;nica Vida and was conducted in accordance with the Declaration of Helsinki.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eA total of 1,008 records of operable breast cancer patients treated with neoadjuvant chemotherapy were included. The median age was 54 years, and the majority of patients belonged to the contributory health regime. The most prevalent histological subtype was luminal B, accounting for 44%, followed by triple-negative (22%), luminal A (19.15%), and HER2+ (14.2%). Among the patients, 77.1% (n\u0026thinsp;=\u0026thinsp;778) received an anthracycline and taxane-based chemotherapy regimen, and 22% also received anti-HER2 therapy. A complete treatment regimen was administered to 99.4% of the patients.\u003c/p\u003e \u003cp\u003eIn Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, the clinical and pathological differences between the groups with a pathological complete response (pCR, n\u0026thinsp;=\u0026thinsp;365) and those without a pathological complete response (no-pCR, n\u0026thinsp;=\u0026thinsp;640) were analyzed. The median age was significantly lower in the pCR group (52.4 years) than in the no-pCR group (56 years) (p\u0026thinsp;\u0026lt;\u0026thinsp;0.0001). In terms of histological grade, Grade 3 tumors were more common in the pCR group (63.8% vs. 44.1%), whereas Grade 2 and Grade 1 tumors were more common in the no-pCR group (45% and 10.9%, respectively) (p\u0026thinsp;\u0026lt;\u0026thinsp;0.0001). For hormone receptors, the pCR group presented a greater percentage of hormone receptor-negative tumors (50.7% vs. 26.4%) than did the no-pCR group (p\u0026thinsp;\u0026lt;\u0026thinsp;0.0001). The Ki67 index, an indicator of cellular proliferation, was also significantly greater in the pCR group (median 50 vs. 35; p\u0026thinsp;\u0026lt;\u0026thinsp;0.0001). No significant differences in tumor size at diagnosis were observed between the two groups (median of 21 mm in the pCR group vs. 23 mm in the no-pCR group; p\u0026thinsp;=\u0026thinsp;0.333). Finally, lymph node involvement at diagnosis was significantly lower in the pCR group (32.3% vs. 69.8% in the no-pCR group; p\u0026thinsp;\u0026lt;\u0026thinsp;0.0001). \u003cb\u003e(\u003c/b\u003eTable\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e\u003cb\u003e).\u003c/b\u003e\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparison of clinical and pathological differences between groups with and without pathological complete response (pCR)\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCharacteristics\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003epCR (n\u0026thinsp;=\u0026thinsp;365)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eNo-pCR (n\u0026thinsp;=\u0026thinsp;640)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eP Value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eMedian Age\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e52.4 (16.71)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e56 (19.42)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eHistological Grade\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGrade 1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e19 (5.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e70 (10.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGrade 2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e113 (31%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e288 (45%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGrade 3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e233 (63.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e282 (44.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eHormone Receptors (%)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePositive\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e180 (49.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e471 (73.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNegative\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e185 (50.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e169 (26.4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eKi67 Median (IQR)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e50 (30\u0026ndash;80)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e35 (20\u0026ndash;60)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eHistological Subtype\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDuctal\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e339 (92.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e578 (90.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLobular\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10 (2.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e36 (5.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOther\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e16 (4.4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e26 (4.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eTumor Size (mm) at Diagnosis\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e21 (27)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e23 (26)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.333\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eLymph Node Involvement at Diagnosis\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e118 (32.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e447 (69.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e247 (67.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e192 (30%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eAs shown in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, treatment differences between patients who achieved pCR and those who did not achieve pCR were analyzed. The anthracycline and taxane-based neoadjuvant regimens were the most commonly used regimens in both groups and were more common in the no-pCR group (83.4% vs. 65.2% in pCR). Conversely, the use of trastuzumab alongside an anthracycline and taxane regimen was significantly greater in the pCR group (34.2% vs. 15%; p\u0026thinsp;\u0026lt;\u0026thinsp;0.0001). With respect to the type of surgery, quadrantectomy with sentinel lymph node biopsy was more common in the pCR group (47.9% vs. 32.3%), whereas modified radical mastectomy was more common in the no-pCR group (38% vs. 25.5%) (p\u0026thinsp;\u0026lt;\u0026thinsp;0.0001). Adjuvant hormone therapy with tamoxifen was similar between the two groups (53.4% in the pCR group vs. 57.5% in the no-pCR group), but aromatase inhibitors were more commonly used in the no-pCR group (20.9% vs. 8.5%; p\u0026thinsp;\u0026lt;\u0026thinsp;0.0001). No significant differences were found in the use of adjuvant radiotherapy between the groups (p\u0026thinsp;=\u0026thinsp;0.246). (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eDifferences between groups with and without pathological complete response (pCR)\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eType of Treatment\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003epCR\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eNo-pCR\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eP Value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eNeoadjuvant Regimen\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBased on Anthracyclines\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0 (0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4 (0.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBased on Anthracyclines and Taxanes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e238 (65.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e534 (83.4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBased on Taxanes Alone\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2 (0.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e6 (0.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAnthracyclines\u0026thinsp;+\u0026thinsp;Taxanes\u0026thinsp;+\u0026thinsp;Trastuzumab\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e125 (34.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e96 (15%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eType of Surgery\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMastectomy\u0026thinsp;+\u0026thinsp;Axillary Dissection\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e93 (25.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e243 (38%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMastectomy\u0026thinsp;+\u0026thinsp;Sentinel Node Biopsy\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e34 (9.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e58 (9.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eQuadrantectomy\u0026thinsp;+\u0026thinsp;Sentinel Node Biopsy\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e175 (47.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e207 (32.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eQuadrantectomy\u0026thinsp;+\u0026thinsp;Axillary Dissection\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e63 (17.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e132 (20.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eAdjuvant Hormone Therapy\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.0001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTamoxifen\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e195 (53.4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e368 (57.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAromatase Inhibitors\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e31 (8.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e134 (20.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNone\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e139 (38.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e137 (21.4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eAdjuvant Radiotherapy\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.246\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e355 (97.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e628 (98.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10 (2.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e12 (1.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003ePatient survival was assessed via the Kaplan‒Meier method (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e), which revealed significant differences in cumulative survival between patients with and without pathological complete response (pCR) over a follow-up period of up to 80 months. This graph indicated that patients who achieved a pathological complete response (pCR) had significantly better survival than those who did not. As the follow-up period increased, the separation between the curves of the two groups became more evident, suggesting a significant difference in survival outcomes, according to the log-rank test (p\u0026thinsp;=\u0026thinsp;0.002). The \"complete\" group curve (in green) remained higher and more stable than the \"no\" group curve (in blue), suggesting that pCR is associated with better long-term survival.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFinally, the behavior of patients with lymph node involvement in the initial stage was evaluated. In total, 56.8% (n\u0026thinsp;=\u0026thinsp;568) presented with lymph node involvement at the time of diagnosis. Among these patients, 76.4% continued to have a tumor burden in the axillary lymph nodes following neoadjuvant treatment. In the remaining group (23.5%), no lymph node involvement was found in the postsurgical pathological analysis. Among these patients, 53.7% underwent axillary lymph node dissection.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eA pathological complete response was observed in 36.2% (365) of the evaluated patients. The remaining 63.5% (640) did not achieve a pathological response or achieved only a partial response. Younger age, higher histologic grade tumors, an elevated Ki67 index, negative hormone receptor expression, and lower lymph node involvement at diagnosis were significantly associated with a greater likelihood of achieving pathological complete response (pCR) after neoadjuvant therapy in breast cancer patients. These results are consistent with those of previous studies, which demonstrated that these clinicopathological factors are important predictors of pCR, which is associated with better long-term outcomes, including overall survival.\u003c/p\u003e \u003cp\u003e(\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eStudies such as that by Cort\u0026aacute;zar et al. (\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e) have established that pCR is a robust prognostic marker, especially in aggressive breast cancer subgroups, such as HER2-positive and triple-negative patients. Our finding that a higher Ki67 index, younger age, and hormone receptor negativity are associated with higher pCR rates aligns with these results, highlighting the importance of a tumor\u0026rsquo;s proliferative and molecular profile as predictors of response to neoadjuvant chemotherapy.\u003c/p\u003e \u003cp\u003eRegarding the type of neoadjuvant treatment, our data revealed that patients who achieved pCR tended to receive more intensive chemotherapy combinations, such as anthracycline, taxane, and trastuzumab regimens. This approach is consistent with the results of the NEOSPHERE and TRYPHAENA trials, which have demonstrated the efficacy of intensive chemotherapy regimens in increasing pCR, particularly in HER2-positive tumors (\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e). Additionally, our results indicate that patients who achieved pCR had a greater frequency of conservative surgeries, such as quadrantectomy, which is consistent with the literature suggesting that achieving pCR enables less radical surgical options (\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eOn the other hand, patients without pCR in our study had greater use of aromatase inhibitors and a greater frequency of mastectomy with axillary lymph node dissection. This treatment pattern may reflect both tumor biology, with lower sensitivity to chemotherapy, and the clinical preference for opting for more aggressive and exhaustive treatments in patients with residual disease after neoadjuvant therapy, as described by Masuda et al. in their analyses of triple-negative breast cancer treatment (\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eLong-term survival is also affected by pathological complete response. Kaplan‒Meier curves demonstrated that patients who achieved pCR had better overall survival than did those who did not, underscoring the importance of achieving pCR in the context of breast cancer treatment. This finding is supported by studies such as those by von Minckwitz et al., which showed that pCR is consistently associated with better disease-free and overall survival rates across a variety of molecular breast cancer subtypes (\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe results of this study should be interpreted in light of the following limitations. First, this study is retrospective and based on the clinical records of a single center, which could limit the generalizability of the findings. Second, although measures were taken to reduce selection and information bias, these measures cannot be entirely ruled out. Future multicenter and prospective studies would be useful to validate these findings and further explore the interactions between different clinicopathological factors and treatment response.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThese results demonstrate that factors such as tumor biology and treatment regimens significantly influence the likelihood of achieving pCR and, consequently, long-term survival. This highlights the importance of personalizing neoadjuvant treatment for breast cancer, guided by specific biological characteristics of the tumor, to optimize clinical outcomes.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003col start=\"1\" type=\"1\"\u003e\n \u003cli\u003e\u003cstrong\u003eNAC\u003c/strong\u003e: Neoadjuvant Chemotherapy\u0026nbsp;\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003epCR\u003c/strong\u003e: Pathological Complete Response\u0026nbsp;\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eER\u003c/strong\u003e: Estrogen Receptor\u0026nbsp;\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003ePR\u003c/strong\u003e: Progesterone Receptor\u0026nbsp;\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eHER2\u003c/strong\u003e: Human Epidermal Growth Factor Receptor 2\u0026nbsp;\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eAJCC\u003c/strong\u003e: American Joint Committee on Cancer\u0026nbsp;\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eRCB\u003c/strong\u003e: Residual Cancer Burden\u0026nbsp;\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eIQR\u003c/strong\u003e: Interquartile Range\u0026nbsp;\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eTX\u003c/strong\u003e: Texas\u0026nbsp;\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eUSA\u003c/strong\u003e: United States of America\u0026nbsp;\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Declarations","content":"\u003cul type=\"disc\"\u003e\n \u003cli\u003e\u003cstrong\u003eEthics Approval and Consent to Participate:\u003c/strong\u003e This study was approved by the ethics committee of Cl\u0026iacute;nica Vida, Medell\u0026iacute;n, and Universidad CES. Documents are attached in other supplements.\u0026nbsp;The expedited approval document for the project CIP 0159-10-2022, \u0026quot;Evaluation of Overall Survival and Pathological Response in Patients Who Received Neoadjuvant Therapy with a Diagnosis of Breast Cancer at a Hospital in the City of Medell\u0026iacute;n\u0026rdquo; CTI AE 012 PI.\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eAvailability of Data and Materials:\u003c/strong\u003e All data generated or analysed during this study are included in this published article [and its supplementary information files].\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eCompeting Interests:\u003c/strong\u003e None.\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eFunding:\u003c/strong\u003e Not applicable.\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eAuthors\u0026apos; Contributions:\u003c/strong\u003e SL developed the study protocol, participated in data collection, and contributed to writing the article; AMC participated in data collection and contributed to writing the article; EMV performed the statistical analysis and reviewed the article\u0026apos;s writing; AMN reviewed the study protocol and contributed to writing the article; NL contributed to writing the article.\u0026nbsp;All authors read and approved the final manuscript.\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eAcknowledgments:\u003c/strong\u003e Clara del Pilar Osorio, for your help throughout the manuscript construction process\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eAuthors\u0026apos; Information:\u003c/strong\u003e Sara Loaiza is a gynecologist and obstetrician and completed a subspecialty in mastology. She has a special interest in research and public health.\u003c/li\u003e\n\u003c/ul\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eTerry MB, Colditz GA. Epidemiology and Risk Factors for Breast Cancer: 21st Century Advances, Gaps to Address through Interdisciplinary Science. Cold Spring Harb Perspect Med. 2023;13(9):a041317.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBravo LE, Mu\u0026ntilde;oz N. Epidemiology of cancer in Colombia. Colomb Med. 2018;49(1):9\u0026ndash;12.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eInstituto Nacional de Cancerolog\u0026iacute;a. C\u0026aacute;ncer en cifras. 2022. pp. 1\u0026ndash;2 C\u0026aacute;ncer en cifras.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGao JJ, Swain SM. Luminal A Breast Cancer and Molecular Assays: A Review. Oncologist. 2018;23(5):556\u0026ndash;65.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNational Cancer Institute. Definition of neoadjuvant therapy. 2024. pp. 1\u0026ndash;1 Definition of neoadjuvant therapy.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWolmark N, Wang J, Mamounas E, Bryant J, Fisher B. Preoperative Chemotherapy in Patients With Operable Breast Cancer: Nine-Year Results From National Surgical Adjuvant Breast and Bowel Project B-18. JNCI Monogr. 2001;2001(30):96\u0026ndash;102.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFisher B, Anderson S, Tan-Chiu E, Wolmark N, Wickerham DL, Fisher ER, et al. Tamoxifen and Chemotherapy for Axillary Node-Negative, Estrogen Receptor\u0026ndash;Negative Breast Cancer: Findings From National Surgical Adjuvant Breast and Bowel Project B-23. J Clin Oncol. 2001;19(4):931\u0026ndash;42.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003evon Minckwitz G, Untch M, Blohmer JU, Costa SD, Eidtmann H, Fasching PA, et al. Definition and Impact of Pathologic Complete Response on Prognosis After Neoadjuvant Chemotherapy in Various Intrinsic Breast Cancer Subtypes. J Clin Oncol. 2012;30(15):1796\u0026ndash;804.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGreen MC, Buzdar AU, Smith T, Ibrahim NK, Valero V, Rosales MF, et al. Weekly Paclitaxel Improves Pathologic Complete Remission in Operable Breast Cancer When Compared With Paclitaxel Once Every 3 Weeks. J Clin Oncol. 2005;23(25):5983\u0026ndash;92.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBear HD, Anderson S, Brown A, Smith R, Mamounas EP, Fisher B, et al. The Effect on Tumor Response of Adding Sequential Preoperative Docetaxel to Preoperative Doxorubicin and Cyclophosphamide: Preliminary Results From National Surgical Adjuvant Breast and Bowel Project Protocol B-27. J Clin Oncol. 2003;21(22):4165\u0026ndash;74.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKaufmann M, Hortobagyi GN, Goldhirsch A, Scholl S, Makris A, Valagussa P, et al. Recommendations From an International Expert Panel on the Use of Neoadjuvant (Primary) Systemic Treatment of Operable Breast Cancer: An Update. J Clin Oncol. 2006;24(12):1940\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCortazar P, Zhang L, Untch M, Mehta K, Costantino JP, Wolmark N, et al. Pathological complete response and long-term clinical benefit in breast cancer: the CTNeoBC pooled analysis. Lancet. 2014;384(9938):164\u0026ndash;72.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRodr\u0026iacute;guez M, Gonz\u0026aacute;lez DM, El-Sharkawy F, Casta\u0026ntilde;o M, Madrid J. Respuesta patol\u0026oacute;gica completa de pacientes con c\u0026aacute;ncer de mama HER2 positivo tratadas con quimioterapia neoadyuvante en Colombia. 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Revista Colombiana de Hematolog\u0026iacute;a y Oncolog\u0026iacute;a. 2023;9(Supl):178\u0026ndash;81.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGianni L, Pienkowski T, Im YH, Roman L, Tseng LM, Liu MC et al. Abstract S3-2: Neoadjuvant Pertuzumab (P) and Trastuzumab (H): Antitumor and Safety Analysis of a Randomized Phase II Study ('NeoSphere\u0026rsquo;). Cancer Res. 2010;70(24_Supplement): S3-2-S3-2.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSchneeweiss A, Chia S, Hickish T, Harvey V, Eniu A, Hegg R, et al. Pertuzumab plus trastuzumab in combination with standard neoadjuvant anthracycline-containing and anthracycline-free chemotherapy regimens in patients with HER2-positive early breast cancer: a randomized phase II cardiac safety study (TRYPHAENA). Ann Oncol. 2013;24(9):2278\u0026ndash;84.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMasuda N, Lee SJ, Ohtani S, Im YH, Lee ES, Yokota I, et al. Adjuvant Capecitabine for Breast Cancer after Preoperative Chemotherapy. N Engl J Med. 2017;376(22):2147\u0026ndash;59.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Breast cancer, neoadjuvant therapy, pathological complete response, survival, retrospective cohort study","lastPublishedDoi":"10.21203/rs.3.rs-5477374/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5477374/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eIntroduction:\u003c/h2\u003e \u003cp\u003eBreast cancer is the most common cancer among women worldwide. Neoadjuvant therapy (NAC) aims to reduce tumor size before surgery and assess the tumor's biological response to treatment. Pathological complete response (pCR) is an important marker of oncological outcomes, but its evaluation in the Colombian population is limited. This study aimed to evaluate pCR and its relationship with overall survival in breast cancer patients who received NAC at a hospital in Medell\u0026iacute;n.\u003c/p\u003e\u003ch2\u003eMethodology:\u003c/h2\u003e \u003cp\u003eThis is a retrospective cohort observational study conducted at Cl\u0026iacute;nica Vida, Medell\u0026iacute;n, between 2017 and 2023, including 1,008 breast cancer patients treated with NAC. Sociodemographic, histological, and treatment variables were evaluated. Bivariate analyses and the Kaplan-Meier test were used to assess survival.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eA total of 36.2% of the patients achieved pCR, which was associated with better overall survival (95.1% vs. 91.1%). Factors associated with pCR included younger age, higher histological grade, elevated Ki67, negative hormone receptors, and lower lymph node involvement. The use of anthracycline-based chemotherapy, taxanes, and Trastuzumab was more common in pCR. Most patients with pCR underwent conservative surgery and sentinel lymph node biopsy.\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e \u003cp\u003eFactors such as tumor biology and therapeutic regimen significantly influence the likelihood of achieving pCR and improving long-term survival. This highlights the importance of personalizing NAC in breast cancer, guided by specific biological characteristics of the tumor to optimize clinical outcomes.\u003c/p\u003e","manuscriptTitle":"Pathological Response to Neoadjuvant Therapy in Breast Cancer Patients and Its Relationship with Survival: A Retrospective Cohort Study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-12-19 11:26:13","doi":"10.21203/rs.3.rs-5477374/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"9a802332-ac19-415c-89a1-1355ab15c65c","owner":[],"postedDate":"December 19th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-11-25T14:08:58+00:00","versionOfRecord":[],"versionCreatedAt":"2024-12-19 11:26:13","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-5477374","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5477374","identity":"rs-5477374","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}