Risk factors for local recurrence in patients with clinical stage II/III low rectal cancer: A multicenter retrospective cohort study in Japan

Background Identifying risk factors for local recurrence (LR) is pivotal in optimizing rectal cancer treatment. Total mesorectal excision (TME) and lateral lymph node dissection (LLND) are the standard treatment for advanced low rectal cancer in Japan. However, large‐scale studies to evaluate risk factors for LR are limited. Methods Data from 1479 patients with clinical stage II/III low rectal cancer below the peritoneal reflection, surgically treated between January 2010 and December 2011 across 69 hospitals, were analyzed. Fine–Gray multivariable regression modeling was used to identify risk factors associated with LR. Two models were developed: one using preoperative factors only, and the other incorporating operative and postoperative factors. Results Across the entire cohort, the 5‐year cumulative incidence of LR was 12.3% (95% confidence interval, 10.7–14.1). The multivariable analysis associated LR with various preoperative (body mass index, distance from anal verge, cN category, and histological subtype), treatment‐related (neoadjuvant therapy, and LLND), and postoperative (pT, pN, and resection margins) risk factors. For patients without neoadjuvant treatment, LR risk was unacceptably high with two or three preoperative risk factors (body mass index ≥25 kg/m2, distance from anal verge ≤4.0 cm, non‐well/moderately differentiated adenocarcinoma). The 5‐year cumulative incidence of LR was 24.7% in patients treated without LLND and 22.9% in patients treated with LLND. Conclusion This large multicenter cohort study identified some risk factors for LR in the setting where upfront TME was predominant, offering insights to optimize rectal cancer treatment. In this multicenter cohort study, we examined preoperative and postoperative risk factors for LR after low rectal cancer surgery. For patients without neoadjuvant treatment, LR risk was unacceptably high with two or three preoperative risk factors (BMI, distance from anal verge, histological subtype).