Pretreatment Immune Status, Predicts Response to Definite Chemo Radiotherapy in Advanced Stages of Cervical Cancer Patients.

Objective To evaluate the prognostic role of pretreatment CD4 + , CD8 + T lymphocytes in predicting response to definite chemo radiotherapy in advanced cervical cancer. Design: A hospital-based prospective one-year follow-up study.

This observational study was conducted on 74 patients with advanced cervical cancer. Pretreatment CD4 + and CD8 + levels in cervical cancer tissue and peripheral blood was noted and quantitatively assessed in patients with complete remission or persistent disease after one year of follow-up.

There was a statistically significant association of tumour volume with the remission or persistence of disease. In peripheral blood, mean CD4 + score and CD4 + /CD8 + ratio were significantly higher while mean CD8 + score is significantly lower in patients with remission. Similar results were seen in tumour tissue as well. On Receiver Operating Curve analysis, the cut-off value of CD4 + , CD8 + and CD4 + /CD8 + ratio in predicting remission or persistent disease in peripheral blood was 20.09, 18.51 and 0.41 while in tumor tissue was 19.71, 20.99 and 0.20, respectively.

The patients with tumor volume < 100 cm 2 have much higher chances of remission. The patients with higher CD4 + and CD4 + / CD8 + ratio, both in peripheral blood as well as tumor tissue, have higher chances of remission. The cut-off value of CD4 + , CD8 + and CD4 + /CD8 + ratio in predicting remission or persistent disease in peripheral blood was 20.09, 18.51 and 0.41 while in tumor tissue was 19.71, 20.99 and 0.20, respectively.

Immune status, Tumor-infiltrating lymphocytes, Cancer cervix, Chemotherapy

The vaccination and screening programmes for carcinoma cervix are not being implemented to their maximum potential across the globe, resulting in patients presenting with advanced stages of the disease and a poor outcome with large individual variability in response to standard treatment [1–4]. Individualising the tumour therapy is thus needed by considering the factors which influence and predict the treatment responses. Studies have shown a positive correlation of immunological parameters with staging and prognosis of various cancers [5]. Changes in the frequencies of CD4 + & CD8 + T cells in the peripheral blood & the tumour tissue may be related to the overall cancer prognosis [6]. This study was planned to evaluate the relationship of the immune cell infiltration and prognosis of the disease managed with standard treatment. The primary objective of the study was to calculate the cut-off value of CD4 + , CD8 + and CD4 + /CD8 + ratio in peripheral blood and tumor tissue predicting the outcome of the standard treatment, i.e., either complete remission (CR) or persistence of disease (PD). The secondary objectives were comparison of tumour infiltrating lymphocytes (TILs) in cervical cancer tissue & peripheral blood in a cohort of cervical cancer patients and finding out any relationship of these lymphocytes subpopulation with menopausal status, ECOG (The Eastern Cooperative Oncology Group) performance status of the patient, tumour size & FIGO (The International Federation of Gynaecology and Obstetrics) staging of the disease [7, 7]. The demographic parameters and TIL levels were also compared between the patients with CR to those with PD.

and Method This observational study was conducted in the Obstetrics & Gynaecology, and Oncology department of Mahatma Gandhi Medical College & Hospital, Jaipur, after institutional ethical committee approval. The study population comprised of the selected patients of 18–65 years of age, who were suffering from advanced stages of uterine cervical cancer (FIGO stage IIB to IIIC) of any size, and had not received chemo radiotherapy at the time of the study. Immune-compromised and those with performance status ECOG-3 or more were excluded. A total of 86 patients, fulfilling the inclusion criteria, were enrolled for the study after informed consent. Among these, 12 patients were subsequently excluded, as 2 underwent radical hysterectomy, 1 died due to disease-associated complications, and 9 were lost to follow-up. Detailed history, clinical examination and required haematological & radiological investigations were done, as and when indicated. Samples of peripheral blood (3 mL venous blood in EDTA vials) and cervical cancer tissue (punch biopsy) were collected; single-cell suspension was prepared by mechanical & enzyme digestion method for evaluation of TILs, i.e., infiltration of CD4 + and CD8 + cells by FACS (Fluorescence Activated Cell Sorter). Patients were then sent for CCRT (Concurrent Chemo radiotherapy) with standard 2019 NCCN guideline regime, and counseling was done for follow-up, every 3 months twice, & then on completion of a year of treatment. Patients were then categorized as CR, when there is no evidence of disease after a year of follow-up, or PD, with residual tumour or recurrence (clinically, histologically or radiologically). For qualitative data in the Microsoft Excel sheet, Chi-square test was used, and for quantitative data, unpaired t-test and analysis of variance (ANOVA) was used to find a significant association. Box and whiskers plot was used for graphical representation of quantitative data, and bar diagram and pie chart for qualitative data. Receiver operating characteristics (ROC) curve was used to assess the cut-off value of CD4 + , CD8 + and CD4 + /CD8 + ratio in patients with CR and PD, both in peripheral blood as well as in tumour tissue.

The demographic details of 74 subjects are tabulated in Table 1, the majority (54%) of the patients belonged to the 46–55 years age group. Only 57% belonged to the premenopausal group, 58% had more than 4 parities. Performance status wise, 58% of patients belonged to ECOG 1, 27% to ECOG 2, and only 15% to ECOG 0, and those with performance status 3 and above were excluded. In 64% of patients, symptoms were present for 6–12 months, vaginal bleeding being the chief complaint in most (80%). Among them, 33% of patients belonged to stage III B, 24% to stage II B, 23% had stage III C while 20% to stage III A. 73% of patients had tumor volume less than 100 cm3 & 77% did not have lymph node metastasis. Post-treatment, 82.43% patients had complete remission while 17.56% had persistent disease. Table 1. | Variables | Number (n = 74) | Percentage (%) | |---|---|---| | Age in completed years | || | 25–35 years | 6 | 8 | | 36–45 years | 18 | 24 | | 46–55 years | 40 | 54 | | > 55 years | 10 | 14 | | Menstrual status | || | Premenopausal | 42 | 57 | | Postmenopausal | 32 | 43 | | Parity | || | 4 | 43 | 58 | | Performance status | || | ECOG0 | 11 | 15 | | ECOG1 | 43 | 58 | | ECOG2 | 20 | 27 | | Symptoms | || | BleedingPV | 59 | 80 | | DischargePV | 48 | 65 | | AbdominalPain | 13 | 18 | | LowBackache | 56 | 76 | | Duration of symptoms | || | 12 months | 9 | 12 | | Clinical stage | || | II B | 18 | 24 | | IIIA | 15 | 20 | | III B | 24 | 33 | | III C | 17 | 23 | | Tumor volume | || | 100cm2 | 20 | 27 | | LN metastasis | || | Yes | 17 | 23 | | No | 57 | 77 | The statistical analysis revealed the mean CD4 + and CD4 + /CD8 + ratio to be significantly higher in peripheral blood than tumor tissue, while CD8 + scores significantly higher in tumor tissue than peripheral blood. Both in peripheral blood and tumor tissue, there was no significant difference in CD4 + , CD8 + and CD4 + /CD8 + score in relation to ECOG performance, lymph node metastasis & FIGO staging of the cervical cancer. In the peripheral blood, an increase in the tumor volume was associated with the decline in CD4 + cells, increase in CD8 + cells and decline in CD4 + /CD8 + ratio. In the tumor tissue, mean CD8 + score was significantly higher in patients with tumor volume > 100 cm3 than patients with tumor volume < 100 cm3. There was a significant difference in mean TIL score in patients with CR and PD, in both peripheral blood and tumor tissue. The mean CD4 + score and CD4 + /CD8 + ratio in patients with CR was significantly higher than in patients with PD while mean CD8 + score was significantly lower in patients with CR than in patients with PD. Figure 1 shows the distribution of patients with CR and PD according to the tumor volume. Statistically, there was a significant association of tumor volume with CR or PD. Those patients with tumor volume > 100 cm3 had higher chance of persistence disease in comparison to patients with tumor volume < 100 cm3. There was no significant association of age, parity, menopausal and performance status, symptoms of the disease & their duration, clinical staging and lymph node metastasis with CR or PD. Figure 2 shows the Box and Whiskers plot of CD4 + and CD8 + in tumor tissue in patients with CR and PD. The entire range of CD4 + in patients with CR was 8.84–39.94, with median of 27.51, and in PD, it was 8.20 to 36.59 with median of 22.14. The CD8 + range in patients with CR was 10.27 to 261.50 & median of 30.32, & in PD it was 20.0 to 141.0 & median 70.47. Figure 3 shows the Box and Whiskers plot of CD4 + /CD8 + ratio in peripheral blood in patients with CR and PD, the median score of CD4 + /CD8 + ratio in CR was found to be significantly higher than that in PD. For the primary objective of the study, which is to calculate the cut-off value of TILs in predicting the outcome of treatment, ROC curve analysis was done. The cut-off of CD4 + in the peripheral blood was found to be 20.09 for CD4 + , with sensitivity of 84.61%, 18.51 for CD8 + , with sensitivity of 92.30%. Figure 4 shows the cut-off for CD4 + /CD8 + ratio in the peripheral blood, it was 0.41 with sensitivity of 84.61% in predicting CR or PD, the patients having CD4 + /CD8 + ratio 0.41 will have PD after one year of treatment. While studying the TILs in the tumor tissue, the cut-off value of CD4 + in tumor tissue was found to be 19.71 with sensitivity of 84.61, for CD8 + it is 20.99 with sensitivity of 84.61%. Figure 5 shows cut-off for CD4 + /CD8 + ratio in tumor tissue, which was 0.20 with sensitivity of 84.61%, patients having ratio of 0.20 will have PD after one year of follow-up.

TILs were found to be associated with a better prognosis in many studies, and dysfunction of TILs was linked to failure of immune surveillance against cancer [8–12]. Several researchers have studied this correlation of TIL-mediated immune surveillance against cancer and prognosis in a few cancers, e.g., pancreatic, ovarian and breast cancers [13–15]. Change in immunological parameters in cancer cervix patients resulting in anti-tumour immune system dysfunction has also been observed [16–18]. CD4 + T cells initiate and maintain the anticancer immune responses, these are needed to produce the CD 8+ cells during the primary antigen-specific response, which can then develop into long-lived functional memory cells. CD4+ regulatory T cells can suppress the anti-tumor immunity in the self, as well as foreign antigen encoded by tumor viruses [19]. Quantitative analysis of TILs in the cancer milieu may provide clues for elucidating the possible cancer host immune interactions in human cervical carcinoma. The primary result of our study was an evidence of infiltration of CD4 + and CD8 + lymphocyte subpopulation in tumour tissue of cervical cancer patients, CD4 + lymphocytes being significantly higher in the peripheral blood as compared to their infiltration in the cervical tumour tissue. The TILs, therefore, had a reversed CD4 + /CD8 + ratio in the tumour tissue compared to that of peripheral blood. Diptimoy Das et al. in 2018, have observed that the proportion of CD4 + cell and the CD4 + /CD8 + cell ratio was significantly lower in cervical cancer tissue than in the peripheral blood, this finding is consistent with our results [20]. These results, therefore, indicate that in patients with cervical cancer, T-cell-mediated immunity was impaired, this impairment was more distinct in the cervical cancer tumor tissue microenvironment than that present in the peripheral blood. Few researchers have further added that among the different TILs, CD4 + , CD8 + , CD25, CD4 + 5, and regulatory T cells (Foxp 3) were the significant ones [21, 22]. Loddenkemper et al. in 2009, while assaying, revealed that HPV-derived tumors have a significantly higher number of infiltrating lymphocytes and FOXP3+Tregs when compared with three other common tumor types [23]. Similar to these studies, in our study, though statistically insignificant, we observed a reversed CD4 + /CD8 + ratio in cervical cancer. The immune suppression induced by altered distribution of lymphocyte subsets, depends on the tumour aetiology, their location, histological type and clinical staging, therefore, further subsets of CD4 + and CD8 + were also compared in the different subgroups of the study population that were made according to the menopausal status, parity, performance status, symptoms and their duration & clinical staging of disease, tumour size and lymph node metastasis. The CD4 + /CD8 + cell ratio was found to be significantly higher in peripheral blood and also in tumour tissue of premenopausal women in comparison to post-menopausal women. This change can be related to the age of the patient, which was considered by a few scientists in the past. Wu, et al. in 2020 reported a significantly higher T cell proportion in tumour tissue in the age ≤ 47 group than in the age > 47 group [24]. These findings suggest that the development of cervical cancer at a relatively young age can be attributed to host immune suppression as a result of escape from immune surveillance which may be responsible for a clinically viable tumour at a young age in premenopausal women [25]. Performance status-wise, though the changes found in the TILs were statistically not significant, there was lowering of CD4 + while an increase in CD8 + counts, thus net lowering of CD4 + /CD8 + ratio in tumor tissue associated with progressive worsening of ECOG performance scores from zero to 2. In order to examine the possibility of changes of regional immune response to correlate with the disease spread, we observed the subpopulations of TILs in patients with and without lymph node metastasis, which was found to be insignificant. Contrary to this, there was a significantly higher infiltration of CD8 + T cells, a higher ratio of CD8 + /CD4 + T cell, and a higher ratio of CD 8 + /Tregs in the patients with tumors that have not metastasized to the tumor-draining lymph node, showing that a robust response of CD8 + cells is usually associated with no lymph node metastasis [26]. An increase in the tumor volume was associated with the significant decline in CD4 + cells, increase in CD8 + and decline in CD4 + /CD8 + ratio in tumor tissue and peripheral blood. Wu et al. in 2020 reported a significantly higher levels of CD8 + T cells, DCs, total monocytes, CD14 + and CD16 + monocytes in more voluminous tumors, resulting in concordance with our results, though not consistent with study results of Diptimoy Das et al. in 2018 who detected higher amount of tumour infiltration with both CD4 + and CD8 + in the more voluminous tumours [20, 24]. The mean CD4 + score and CD4 + /CD8 + ratio was found to be significantly higher and CD8 + significantly lower in peripheral blood as well as in tissue of patients with CR when compared to those with PD. In contrast to our results, Wu et al. (2020) in their study observed that the CD4 + cell proportion and CD4 + /CD8 + cell ratio in tumour tissue were significantly decreased in the patients who had recurrence, as compared to those who are disease-free, while the CD8 + cell proportion was significantly increased [24]. The single variable showing statistically significant association with remission or persistence of the disease in our study was tumour volume. Those patients with tumour volume > 100 cm3 had higher chance of PD in comparison to patients with tumour volume < 100 cm3. Mounting evidences have shown that a cytotoxic mechanism was found to be the key mechanism by which TILs control the tumor growth, & CD8 + T-cells sub-population to be effective in the anti-tumour response [27]. It is desirable that the tumour site is infiltrated with high numbers of activated CD8 + TILs [28]. For their optimal functioning, CD8 + T-cells usually require CD4 + T-cells, which initiate and maintain the anticancer immune response, and help the CD8 + cells to develop long-lasting functional memory cells during the primary antigen-specific response [9]. Our findings further explicate that the decrease in CD4 + cells is crucial for reversed CD4 + /CD8 + ratio during the progression of disease, implying poor anti-tumour response.

The present study, comprising of patients in advanced stages of uterine cervical cancer, showed that 82.43% of patients had CR while 17.56% of patients had PD after one year of follow-up. The single variable showing a statistically significant association with remission or persistence of the disease was tumor volume. Those patients with tumor volume > 100 cm2 have higher chance of persistence disease in comparison to patients with tumor volume < 100 cm2. Both in peripheral blood as well as in tumor tissue, the mean CD4 + score and CD4 + /CD8 + ratio in patients with CR was significantly higher than in patients with PD while mean CD8 + score was significantly lower in patients with CR than in patients with PD. Thus, patients with higher CD4 + score and CD4 + /CD8 + ratio while lower CD8 + score have higher chances of CR. This single-center study having limited number of patients concluded that cut-off value of CD4 + , CD8 + and CD4 + /CD8 + ratio in peripheral blood, predicting CR or PD was 20.90, 18.51 and 0.41, respectively while cut-off value of CD4 + , CD8 + and CD4 + /CD8 + ratio in tumor tissue, predicting CR or PD was 19.71, 20.99 and 0.20, respectively. However, more multi-centric studies recruiting a large number of patients are required to arrive at a definite conclusion regarding these cut-off values. Dr. Swati Garg she is working as Principal & Controller, Mahatma Gandhi Medical College & Hospital, Jaipur, Professor, department of obstetrics & gynaecology. She has completed her MBBS & MS from SMS Medical College, Jaipur. She is fellow association of minimal invasive surgeons of India (FAMASI), and fellow Indian college of obstetrician & gynaecology. She has done postgraduate diploma in clinical research and also in hospital & health care management from symbiosis, Pune. She is a life member of IMA, IMS, NARCHI, SELSI, ISOPARB, AMASI, ISCCP, PCOS Society, Society of Mid Life Management and Endometriosis Society of India. She is a keen learner, an enthusiastic UG & PG teacher, and her field of interest is managing high risk pregnancy. Author contribution All authors contributed the study conception and design. Material preparation, data collection and analysis were performed by Dr. Swati Garg and Dr. Rajaat Vohra. The first draft of manuscript was written by Dr. Swati Garg and Dr. Reshu Gupta and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript. Declarations Conflict of interest The authors declare that they have no competing interests. Footnotes Dr. Swati Garg, MS is a Professor & Unit Head, Department of Obstetrics & Gynaecology, Mahatma Gandhi Medical College & Hospital, Jaipur; Dr. Usha Shekhawat, MS is a Professor & Head, Department of Obstetrics & Gynaecology, Mahatma Gandhi Medical College & Hospital, Jaipur; Dr. Rajaat Vohra, MD is a Professor, Department of Community Medicine, Mahatma Gandhi Medical College & Hospital, Jaipur; Dr. Reshu Gupta, MD is a Professor, Department of Physiology, Rajasthan University of Health & Sciences, Jaipur. Publisher's Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

- 1.Prof. Marc Brisson, Prof. Jane J Kim, Karen Canfell, Melanie Drolet, Guillaume Gingras, Emily A Burger et al., Impact of HPV vaccination and cervical screening on cervical cancer elimination: a comparative modelling analysis in 78 low-income and lower-middle-income countries. www.thelancet.com Vol 395 February 22, 2020. [DOI] [PMC free article] [PubMed] - 2.Chee KC, Gulzhanat A, Talshyn U, Kuralay K, Azliyati A. Human papillomavirus infection and cervical cancer: epidemiology, screening, and vaccination—review of current perspectives. J Oncol 2019. [DOI] [PMC free article] [PubMed] - 3.Todo Y, Watari H. Concurrent chemoradiotherapy for cervical cancer: background including evidence-based data, pitfalls of the data, limitation of treatment in certain groups. Chin J Cancer Res. 2016;28(2):221–227. doi: 10.21147/j.issn.1000-9604.2016.02.10. [DOI] [PMC free article] [PubMed] [Google Scholar] - 4.Cho O, Chun M. Management for locally advanced cervical cancer: new trends and controversial issues. Radiat Oncol J. 2018;36(4):254–264. doi: 10.3857/roj.2018.00500. [DOI] [PMC free article] [PubMed] [Google Scholar] - 5.Riazi Rad F, Ajdary S, Omranipour R, Alimohammadian MH, Hassan ZM. Comparative analysis of CD4+ and CD8+ T cells in tumor tissues, lymph nodes and the peripheral blood from patients with breast cancer. Iran Biomed J. 2015;19(1):35–44. doi: 10.6091/ibj.1289.2014. [DOI] [PMC free article] [PubMed] [Google Scholar] - 6.Durgeau A, Virk Y, Corgnac S, Mami-Chouaib F (2018) Recent Advances in Targeting CD8 T-Cell Immunity for More Effective Cancer Immunotherapy. Front Immunol. 9:14. Received: 30 November 2017; Accepted: 04 January 2018; Published: 22 January 2018 [DOI] [PMC free article] [PubMed] - 7.Lingappanoor S, Manupati G, Meesala V, Yaragani P, Bachu B, Anchuri S. Assessment of quality of life of cervical cancer patients using ECOG-performance status scale. J Cancer Tumor Int. 2019;9(3):1–8. doi: 10.9734/jcti/2019/v9i330108. [DOI] [Google Scholar] - 8.Bhatla N, Berek JS, CuelloFredes M, Denny LA, Grenman S, Karunaratne K, Kehoe ST, Konishi I, Olawaiye AB, Prat J, Sankaranarayanan R, Brierley J, Mutch D, Querleu D, Cibula D, Quinn M, Botha H, Sigurd L, Rice L, Ryu HS, Ngan H, Mäenpää J, Andrijono A, Purwoto G, Maheshwari A, Bafna UD, Plante M, Natarajan J. Revised FIGO staging for carcinoma of the cervix uteri. Int J Gynaecol Obstet. 2019;145(1):129–135. doi: 10.1002/ijgo.12749. [DOI] [PubMed] [Google Scholar] - 9.Li C, Liu W, Cheng Y. Prognostic significance of metastatic lymph node ratio in squamous cell carcinoma of the cervix. Onco Targets Ther. 2016;9:3791–3797. doi: 10.2147/OTT.S97702. [DOI] [PMC free article] [PubMed] [Google Scholar] - 10.Waldman AD, Fritzand JM, Lenardo MJ. A guide to cancer immunotherapy: from T cell basic science to clinical practice. Nat Rev Immunol. 2020;20:651–668. doi: 10.1038/s41577-020-0306-5. [DOI] [PMC free article] [PubMed] [Google Scholar] - 11.Hendry S, Salgado R, Gevaert T, Russell PA, John T, Thapa B, et al. Assessing tumor infiltrating lymphocytes in solid tumors: a practical review for pathologists and proposal for a standardized method from the International Immuno-Oncology Biomarkers Working Group. Adv Anatomic Pathol. 2017;24(6):311–5. [DOI] [PMC free article] [PubMed] - 12.Dhatchinamoorthy K, Colbert JD, Rock KL. Cancer immune evasion through loss of MHC class I antigen presentation. Front Immunol. 2021;01–27. [DOI] [PMC free article] [PubMed] - 13.Zhang Z, Liu S, Zhang B, Qiao L, Zhang Y, Zhang Y. T cell dysfunction and exhaustionin cancer. Front Cell Dev Biol. 2020;8(17):01–13. doi: 10.3389/fcell.2020.00001. [DOI] [PMC free article] [PubMed] [Google Scholar] - 14.Oken M, Creech R, Tormey D, et al. Toxicity and response criteria of the Eastern Cooperative Oncology Group. AmJClinOncol. 1982;5:649–65. [PubMed] - 15.Xu YF, Lu Y, Cheng H, Shi S, Xu J, Long J, Liu L, Liu C, Yu X. Abnormal distribution of peripheral lymphocyte subsets induced by PDAC modulates overall survival. Pancreatology. 2014;14(4):295–301. doi: 10.1016/j.pan.2014.05.797. [DOI] [PubMed] [Google Scholar] - 16.Lee KH, Kim EY, Yun JS, Park YL, Do SI, Chae SW, Park CH. The prognostic and predictive value of tumor-infiltrating lymphocytes and hematologic parameters in patients with breast cancer. BMC Cancer. 2018;18(1):938. doi: 10.1186/s12885-018-4832-5. [DOI] [PMC free article] [PubMed] [Google Scholar] - 17.Gun SY, Lee SWL, Sieow JL, Wong SC. Targeting immune cells for cancer therapy. Redox Biol. 2019;25:101174. [DOI] [PMC free article] [PubMed] - 18.Tranberg K-G. Local destruction of tumors and systemic immune effects. Front Oncol. 2021;11:708810. [DOI] [PMC free article] [PubMed] - 19.Muenst S, Laubli H, Soysal SD, Zippelius A, Tzankov A, Hoeller S (University Hospital Basel;and University of Basel, Basel, Switzerland). The immune system and cancer evasion strategies: therapeutic concepts (Review). J Internal Med. 2016;279:541–62. [DOI] [PubMed] - 20.Hasenkrug KJ, Chougnet CA, Dittmer U. Regulatory T cells in retroviral infections. PLoS Pathog. 2018;14(2):01–22. doi: 10.1371/journal.ppat.1006776. [DOI] [PMC free article] [PubMed] [Google Scholar] - 21.Das D, Sarkar B, Mukhopadhyay S, Chandranathanerjee, Mondal SB. An altered ratio of CD4+ And CD8+ T lymphocytes in cervical cancer tissues and peripheral blood—a prognostic clue? Asian Pac J Cancer Prev. 2018;19(2):471–8. [DOI] [PMC free article] [PubMed] - 22.Ha D, Tanaka A, Kibayashi T, Tanemura A, Sugiyama D, Wing JB, Lim EL, WengTeng KW, Adeegbe D, Newell EW, Katayama I, Nishikawa H, Sakaguchi S. Differential control of human Treg and effector T cells in tumor immunity by Fc-engineered anti–CTLA-4 antibody. Proc Natl Acad Sci. 2019;116(2):609–18. [DOI] [PMC free article] [PubMed] - 23.Li C, Jiang P, Wei S, et al. Regulatory T cells in tumor microenvironment: new mechanisms, potential therapeutic strategies and future prospects. Mol Cancer. 2020;19(116):01–23. doi: 10.1186/s12943-019-1085-0. [DOI] [PMC free article] [PubMed] [Google Scholar] - 24.Yang Ou, Cannon MJ, Nakagawa M. Regulatory T Cells in Gynecologic Cancer. MOJ Immunol. 2018;6(2):34–42. [PMC free article] [PubMed] [Google Scholar] - 25.Wu Y, Ye S, Goswami S, Pei X, Xiang L, Zhang X, Yang H. Clinical significance of peripheral blood and tumor tissue lymphocyte subsets in cervical cancer patients. BMC Cancer. 2020;20(1):173. doi: 10.1186/s12885-020-6633-x. [DOI] [PMC free article] [PubMed] [Google Scholar] - 26.Chan CK, Aimagambetova G, Ukybassova T, Kongrtay K, Azizan A. Human papillomavirus infection and cervical cancer: epidemiology, screening, and vaccination—review of current perspectives. J Oncol. 2019; Article ID 3257939, 01-11 [DOI] [PMC free article] [PubMed] - 27.Nakagawa M, Yang O, Cannon MJ. Regulatory T Cells in Gynecologic Cancer. MOJ Immunol. 2018;6(2):34–42. [PMC free article] [PubMed] [Google Scholar] - 28.Opzoomer JW, Sosnowska D, Anstee JE, Spicer JF, Arnold JN. Cytotoxic chemotherapy as an immune stimulus: a molecular perspective on turning up the immunological heat on cancer. Front Immunol. 2019 | 10.3389/fimmu.2019.01654. [DOI] [PMC free article] [PubMed] - 29.Gao Q, Qiu S-J, Fan J, Zhou J, Wang X-Y, Xiao Y-S, Yang Xu, Li Y-W, Tang Z-Y. Intratumoral Balance of Regulatory and Cytotoxic T Cells Is Associated With Prognosis of Hepatocellular Carcinoma After Resection. J Clin Oncol. 2007;25(18):2586–2593. doi: 10.1200/JCO.2006.09.4565. [DOI] [PubMed] [Google Scholar]