Risk factors and prognostic significance of lateral pelvic lymph node metastasis in advanced rectal cancer

Background The aim of this study was to elucidate the risk factors for and prognostic value of lateral pelvic lymph node (LPLN) metastasis in advanced rectal cancer patients, including those with stage IV disease. Methods The treatment outcomes of 78 patients with advanced rectal cancer, the lower margin of which was located at or below the peritoneal reflection, who underwent curative-intent surgery with bilateral LPLN dissection from 2005 to 2018 were retrospectively analyzed. Results In total, 78 rectal cancer patients, including 13 patients with stage IV tumors, 9 patients (11.5%) had LPLN metastasis. A multivariate analysis to identify preoperative clinical factors associated with LPLN metastasis showed that tumor location (below the peritoneal reflection: Rb), LPLN metastasis on preoperative imaging and distant metastasis were independent predictors of LPLN metastasis. In addition, metastasis at the regional lymph nodes in the mesorectum was significantly associated with LPLN metastasis. Both the disease-free survival (DFS) and cancer-specific survival (CSS) of patients with LPLN metastasis were significantly worse in comparison to patients without LPLN metastasis, and the CSS of stage IV patients with LPLN metastasis was significantly worse in comparison to stage IV patients without LPLN metastasis. Conclusions Tumor location (Rb), LPLN metastasis on preoperative imaging and distant metastasis were risk factors for LPLN metastasis. The prognosis of rectal cancer patients with LPLN metastasis is poor. There may not be the indication of LPLN dissection in stage IV lower rectal cancer except cases having complaints due to LPLN metastasis.