Impact of Lateral Pelvic Lymph Node Dissection on the Survival of Patients with T3 and T4 Low Rectal Cancer

The aim of this study was to clarify the survival benefit of lateral pelvic lymph node dissection (LPLND) for patients with pathological T3 and T4 (pT3/T4) low rectal cancer. We evaluated the impact of LPLND on survival for pT3/T4 low rectal cancer patients. The primary endpoint of the study was overall survival (OS). The large-scale database of the Japanese Society for Cancer of the Colon and Rectum registration system was accessed and the data were analyzed using a propensity score matching method based on the likelihood of receiving LPLND. Using seven covariates, the propensity scores were calculated with multivariate logistic regression. A total of 499 propensity score-matched pairs of patients were selected from the entire cohort of 1,840 patients who had received curative resection for pT3/T4 low rectal cancer between 1995 and 2004. In the matched cohort, the 5-year OS of the patients who had and had not undergone LPLND were 68.9 and 62.0 %, respectively (p = 0.013; hazard ratio [HR], 0.755; 95 % confidence interval [CI], 0.604-0.944). The 5-year OS of the patients with node-negative disease who had and had not received LPLND differed statistically significantly (5-year OS were 82.1 and 71.4 %, respectively. p = 0.006; HR, 0.579; 95 % CI 0.389-0.862). However, those with node-positive disease did not differ significantly (5-year OS were 55.5 and 53.8 %, respectively. p = 0.415; HR 0.893; 95 % CI 0.681-1.172). The impact of LPLND on OS for patients with node-negative pT3/T4 low rectal cancer was suggested in this retrospective cohort study. To determine true benefits and harms of LPLND, further prospective studies may be warranted.