Is lateral pelvic node dissection necessary after preoperative chemoradiotherapy for rectal cancer patients with initially suspected lateral pelvic node?

Background. Little is known about the effect of lateral pelvic node dissection after preoperative chemoradiotherapy on rectal cancer patients with initially suspected lateral pelvic nodes. The purpose of this study was to identify a subgroup of patients receiving preoperative chemoradiotherapy who can benefit from lateral pelvic node dissection. Methods. The study included 580 patients who underwent preoperative chemoradiotherapy and total mesorectal excision. The lateral pelvic node responses to preoperative chemoradiotherapy were divided: group I (no suspected lateral pelvic node), lateral pelvic node <5 mm pre- and post-chemoradiotherapy; group II (responsive lateral pelvic node), lateral pelvic node >= 5 mm pre-chemoradiotherapy but <5 mm post-chemoradiotherapy; and group III (persistent lateral pelvic node), lateral pelvic node >= 5 mm pre- and post-chemoradiotherapy. Prognostic factors for lateral pelvic node recurrence-free survival, locoregional recurrence-free survival, relapse-free survival, and overall survival were analyzed. Results. In a multivariate analysis, lateral pelvic node response was an independent factor associated with lateral pelvic node recurrence-free survival, locoregional recurrence-free survival, relapse-free survival, and overall survival (P <.05). Group III had significantly poorer lateral pelvic node recurrence-free survival, locoregional recurrence-free survival, relapse-free survival, and overall survival than groups II and I (74.1%, 93.4%, and 98.6%; 71.7%, 89.4%, and 97%; 56.9%, 76.6%, and 81.7 %; 74.9%, 85.7%, and 89.1 %, respectively; P <.05). Group II tended to have poorer lateral pelvic node recurrence-free survival, locoregional recurrence-free survival, relapse-free survival, and overall survival than group I, and the differences in relapse-free survival and overall survival between the 2 groups were not significant (P >.05). Conclusion. Our data suggest that the subgroup with lateral pelvic nodes responsive to preoperative chemoradiotherapy may not benefit from lateral pelvic node dissection, and the subgroup with persistent lateral pelvic node may benefit from lateral pelvic node dissection.