Outcomes and prognostic factors of selective lateral pelvic lymph node dissection with preoperative chemoradiotherapy for locally advanced rectal cancer

The clinical significance of preoperative chemoradiotherapy (CRT) and lateral lymph node dissection (LLND) for locally advanced rectal cancer remains unclear. We have employed total mesorectal excision and selective LLND following preoperative CRT for patients with locally advanced rectal cancer. The validity of our strategy was evaluated. A total of 45 patients with locally advanced rectal cancer who underwent curative surgery after CRT from November 2005 to September 2016 were retrospectively analyzed. LLND was performed only for the patients with lateral lymph nodes suspected to have metastasis based on the pretreatment images. Rates of 5-year overall survival (OS) and 5-year relapse-free survival (RFS) were 85.7 and 61.8%, respectively. Univariate and multivariate analyses detected only histological response (grades 2 and 3 vs. grade 1) as a significant prognostic factor for OS and local recurrence. ypN and ypStage were significant factors for RFS by univariate analysis, while no significant factor was detected by multivariate analysis. There was no significant factor for distant recurrence. In good responders (grades 2 and 3), the local recurrence rate was 0% (P = 0.006, vs. grade 1), while distant recurrence developed in 4 of 20 cases (20%, P = 0.615, vs. grade 1). There was no local recurrence in LLND (-) group regardless the histological response. Although selective LLND with preoperative CRT seems effective and valid for good responders, new treatment strategy is necessary for poor responders. Therefore, development of reliable biomarkers for histological response to CRT is an urgent need.