Prognostic significance of retrieved lymph nodes per specimen in resected rectal adenocarcinoma after preoperative chemoradiation therapy.

Background: Histologic examination of a regional lymphadenectomy specimen ordinarily should include 12 or more lymph nodes. However, in specimens from patients who received preoperative chemoradiotherapy this number has not yet been established.

Methods: From January 1990 to December 2000, 210 patients with rectal adenocarcinoma located between 0 and 10 cm from anal verge with invasion into perirectal fat, tethered or fixed to the pelvis, diagnosed by computed tomography (CT) scan and/or rectal ultrasound were included. All patients received 45 Gy+bolus infusion of 5-FU (450 mg/m2/days 1-5, 28-33 of RT) 4-8 weeks after surgery was performed. Specimens were mapped and sliced. Lymph nodes were studied under clearing or manual techniques. Five-year survival was calculated by Kaplan-Meier method and comparison of groups with log-rank test. Multivariate Cox regression analysis was performed to find risk factors affecting local control and survival.

Results: There were 126 males and 84 females; mean age was 55.2 years. Low anterior resection was performed in 112 patients, abdominoperineal resection in 85, and pelvic exenteration in 13. Total retrieved lymph nodes numbered 2,554, of which 252 contained metastasis. The group was divided into patients with 1-10 retrieved lymph nodes (n=119) and patients with > or = 11 retrieved lymph nodes (n=91). Median follow-up was 49 months. Local recurrence was as follows: 15% in patients with specimens containing 1-10 lymph nodes and conversely 7.4% in those with > or = 11 (p=0.01). Five-year survival of patients with 1-10 lymph nodes was 48%, whereas for those with > or = 11 lymph nodes it was 69% (p=0.02).

Conclusions: Retrieval of at least 11 lymph nodes in the surgical specimen is not only a powerful tool to properly stage patients with rectal adenocarcinoma treated with preoperative chemoradiotherapy and surgery, but it is also of prognostic relevance in that 5-year survival and local recurrence were better in this group of patients.