The efficacy of adjuvant chemotherapy after total mesorectal excision without selective lateral lymph node dissection for locally advanced rectal cancer

The standard treatment for locally advanced rectal cancer (RC) in Japan is TME with or without lateral lymph node dissection (LLND) and subsequent adjuvant chemotherapy. The efficacy of chemotherapy after TME without LLND remains unclear, so we aimed to assess this efficacy. We retrospectively reviewed patients who underwent TME without LLND and received adjuvant chemotherapy between January 2010 and December 2020 at our institution. Relapse-free survival (RFS) and overall survival (OS) were assessed. Prognostic factors for RFS, including tumor location, chemotherapy regimen, and T and N factors were analyzed using univariate and multivariate analyses. Of 197 patients, 117 were eligible. The median age was 66 years (range 26-82). Tumor locations were Ra and Rb in 67 (57%) and 50 (43%) patients. Eighty (68%) and 37 (32%) patients received fluoropyrimidine monotherapy (single agent) and oxaliplatin-based therapy (doublet) as adjuvant chemotherapy. The 3-year RFS rate and 3-year OS rate were 73.6% (95% confidence interval [CI], 64.7-81.0%) and 95.5% (95% CI, 89.6-98.1%), respectively. In the univariate and multivariate analysis, none of these variables were identified as independent prognostic factors for RFS. TME without LLND followed by adjuvant chemotherapy in patients with RC demonstrated favorable 3-year RFS and OS rates.