Lower lymph node yield following neoadjuvant therapy for rectal cancer has no clinical significance

Obtaining 12 lymph nodes following resection for rectal cancer is an important prognostic marker. However, patients who have received neoadjuvant therapy are known to have a lower lymph node yield. We conducted this study to determine the clinical significance of evaluating <12 versus ≥12 lymph nodes in individuals who underwent surgery following neoadjuvant therapy for rectal cancer.

A retrospective analysis of all patients who received neoadjuvant therapy for locally advanced rectal cancer between January 2008 and December 2014 followed by proctectomy was conducted.

In total, 217 patients were treated for rectal cancer. Mean follow-up was 23.4 (interquartile range, 9-40.5) months. Sixty-three (29.0%) patients received neoadjuvant therapy. There was a statistically significant difference in the number of patients with <12 lymph node yield between those who received neoadjuvant therapy and those who did not (27.0% vs. 9.1%, P=0.001). Amongst the 63 patients who received neoadjuvant therapy, lymph node yield of ≥12 was not associated with a statistically significant difference in time to recurrence [hazard ratio (HR) 0.17; 95% confidence interval (CI), 0.01-2.01, P=0.160] or time to death (HR 1.07; 0.15-7.90, P=0.946). Kaplan-Meier curves also did not show any significant difference between those with <12 lymph nodes and those with ≥12 lymph nodes in terms of recurrence and death (P=0.203 and P=0.762 respectively).

Although neoadjuvant therapy reduces the lymph node yield during surgery for locally advanced rectal cancer, this has no significance on the overall survival of the patient.