The association of preoperative radiotherapy and surgery for AJCC stage I-III rectal adenocarcinoma: a population-based study.

Background: With the increasing application of neoadjuvant therapy in rectal adenocarcinoma, there remain many controversies in clinical practical applications. Preoperative radiotherapy (PR) can limit the surgical plane and potentially affect the quality of surgical treatment. This study aimed to investigate the potential impact of PR on the surgical quality of rectal adenocarcinoma.

Methods: This retrospective study analyzed the clinicopathological data from 6,585 AJCC stage I-III rectal adenocarcinoma in the Surveillance, Epidemiology, and End Results (SEER) database from 2010 to 2015. Kaplan-Meier survival analysis and multivariate Cox proportional were used to assess the impact of PR on survival. Propensity score matching (PSM) was employed to balance the baseline covariates between the PR and non-PR groups and to compare postoperative pathological differences.

Results: After PSM, PR did not improve overall survival (OS) in stages I (p = 0.33), II (p = 0.37), and III (p = 0.14) patients. Multivariate Cox analysis indicated that PR was not an independent prognostic factor for patients. Restricted cubic spline (RCS) analysis demonstrated a nonlinear negative correlation between OS hazard ratios and both circumferential resection margin (CRM) and lymph node evaluation (LNE). Compared to the non-PR group, patients in the PR group had lower tumor deposits (TD) (p < 0.001), positive CRM (p = 0.191), and perineural invasion (PNI) (p = 0.001).

Conclusion: PR is not an independent prognostic factor for rectal adenocarcinoma patients. However, PR can reduce the likelihood of TD, CRM, and PNI, thereby potentially influencing the quality of surgery.