Predictors of pathological complete response following neoadjuvant chemoradiotherapy for rectal cancer

Background: Neoadjuvant chemoradiotherapy (NACRT) is an established treatment option for locally advanced rectal cancer (LARC). Patients achieving pathological complete response (pCR) following NACRT have better oncological outcomes and may be subjected to wait and watch policy as well. The aim of this study was to identify predictors of pCR in LARC following NACRT. Materials and Methods: A retrospective analysis of a prospectively maintained colorectal cancer database from January 2018 to December 2019 was undertaken. A total of 129 patients of LARC who were subjected to conventional long course NACRT, followed by surgery were included in the study. Pathological response to NACRT was assessed using Mandard grading system and response was categorized as pCR or not-pCR. Correlation between various clinico pathological parameters and pCR was determined using univariate and multivariate logistic regression analysis. Results: Mean age of patients was 53.79 ± 1.303 years. Complete pathological response (Mandard Gr 1) was achieved in 24/129 (18.6%) patients. Age of patients more than 60 years (P = 0.011; odds ratio [OR] 3.194, 95% confidence interval [CI] 1.274-8.011), interval between last dose of NACRT and surgery >8 weeks (P = 0.004; OR 4.833, 95% CI 1.874-12.467), well-differentiated tumors (P < 0.0001; OR 32.00, 95% CI 10.14–100.97) and node-negative disease (P = 0.003; OR 111.0, 95% CI 2.51–48.03) proved to be strong predictors of pCR. Conclusion: Older age, longer interval between NACRT and surgery, node-negative disease and favorable tumor grade help in achieving better pCR rates. Awareness of these variables can be valuable in counseling patients regarding prognosis and treatment options.