In the early 1980s, approximately 30–40 % of patients experienced local recurrence after undergoing rectal cancer surgery [1]. The introduction of preoperative chemoradiation (CRT) followed by total mesorectal excision (TME) has markedly decreased the recurrence rate in locally advanced rectal cancer [[2], [3], [4]]. However, although recurrence rates have decreased to approximately 5–10 % after preoperative CRT followed by TME, a high rate of local recurrences still occur in the lateral pelvic area [5].

The impact of lateral pelvic lymph node (LPN) metastasis in rectal cancer is a topic of ongoing discussion. A study suggested that LPN metastasis may be considered a locoregional disease, with a prognosis similar to that of stage III and better than that of stage IV rectal cancer [6]. This has led to increased interest in lateral pelvic lymph node dissection (LPND) as a treatment strategy for LPN metastasis. A randomized controlled study also showed that compared to TME alone, TME combined with LPND was more effective in reducing local recurrence, especially in cases affecting the lateral pelvis [7]. Moreover, a recent international collaboration study reported a lower lateral local recurrence rate in TME combined with LPND compared to TME alone, even after preoperative CRT. The study demonstrated that preoperative CRT was insufficient to prevent lateral local recurrence for locally advanced rectal cancer with enlarged LPN before treatment [8]. Based on these findings, the current treatment paradigm for locally advanced rectal cancer with suspected LPN metastasis involves preoperative CRT followed by TME with selective LPND.

Several studies support the oncological benefits of TME with LPND for poor responders to preoperative CRT [[8], [9], [10], [11]]; however, the optimal treatment strategy for good responders remains unclear. Therefore, this study aimed to identify the optimal treatment strategy for patients with rectal cancer who respond well to preoperative CRT, as well as to identify the risk factors for LPN metastasis in these patients.