Pathological Response Has Survival Benefits for Rectal Cancer following Neoadjuvant Therapy

Abstract Background: Studies reporting the results of associated factors of pathological completed response (PCR) and tumor regression response in patients with rectal cancer following neoadjuvant chemoradiation therapy (nCRT) are inconsistent. Objective: The purpose of this study was to identify the prognostic factors of tumor response and outcome in rectal cancer patients. Design: The study was a retrospective analysis. Settings: The study was conducted in a single large institution in Taiwan. Patients: Newly diagnosed rectal cancer patients who underwent nCRT followed by surgery from 2010 to 2014 with 5 years of follow-up. Main Outcome Measures: The primary outcomes were associated factors of pathological completed response and downstaging. The risk factors of survival outcome and disease recurrence were also observed. Results: A total of 169 rectal cancer patients were included. The PCR rate was 17.8%, and the downstaging rate was 60.9%. Patients with a histology type of adenocarcinoma associated with PCR, and patients positive for clinical N stage were associated with downstaging. Kaplan-Meier analysis showed the PCR group performed better to a statistically significant level both in overall survival and disease recurrence free survival than the no PCR group (p= 0.033 & 0.025, respectively). Patients with a downstaging response also showed better overall survival benefits and disease recurrence free survival benefits than their counterparts (both p<0.001). After controlling confounding variables, the risk factors of overall survival were downstaging [Hazard Ratio (HR): 0.40, 95% CI: 0.21-0.74], male, abnormal post-nCRT CEA level and abnormal Hb level. In addition, the protective factors of recurrence were downstaging and having received adjuvant chemotherapy. Limitations: Modest sample size and limited genetic bio-markers information. Conclusions: Among rectal cancer patients who received the neoadjuvant therapy, histology type and clinical N stage were associated with PCR and downstaging, respectively. Downstaging was an important protective factor for better overall survival and recurrence free survival.