Different Impacts of Preoperative Radiotherapy and Chemoradiotherapy on Oncological Outcomes in Patients with Stages II and III Lower Rectal Cancer: A Propensity Score Analysis

Abstract

Background/Aims: The neoadjuvant therapy for locally advanced rectal cancer has been changed from radiotherapy (RT) to chemoradiotherapy (CRT). This study is aimed at evaluating the benefit of CRT in patients with stage II or III lower rectal cancer, with regard to the impact on recurrence. Methods: A total of 474 patients with clinical stage II or III lower rectal cancer who received either preoperative RT ( n = 221) or CRT ( n = 253) followed by total mesorectal excision were identified from our institutional database. Propensity score analysis was performed to mitigate selection biases. Results: Among stage II patients, the CRT group showed a significantly lower 5-year local recurrence rate than the RT group (3.0 vs. 14.8%, p = 0.002). In contrast, among stage III patients, the CRT group showed a significantly lower 5-year distant recurrence rate than the RT group (27.8 vs. 42.6%, p = 0.04) and also a better 5-year recurrence-free survival (64.2 vs. 48.3%, p = 0.03). Conclusions: Addition of concurrent chemotherapy to preoperative RT significantly enhanced the local control in stage II patients and decreased distant recurrence in stage III patients. The oncological benefit of CRT may differ between patients with stage II or III rectal cancer.