Prognostic Analysis According to N Stage and Circumferential Resection Margin in Patients with Locally Advanced Rectal Cancer

Sohn, Yong Ki; Shin, Jin Yong; Hong, Kwan Hee

Abstract

PURPOSE
Efforts must be made to clarify the contribution of lymph node metastasis (NM) to adjuvant (chemo) radiotherapy following a curative resection for rectal cancer as the circumferential resection margin (CRM) has increasingly become a more reliable prognosticator for rectal cancer. This study examined the prognostic impact of NM on local recurrence, disease-free survival. and overall survival rates in curatively resected patients with locally advanced rectal cancer.
METHODS
Two hundred two patients with locally advanced rectal cancer curatively resected in Pusan Paik Hospital from January 1995 to December 2003 were enrolled. These patients were divided into three groups according to lymph node (N) disease (N0: node negative, n=79; N1: 1-3 nodes positive, n=70; N2: > or =4 nodes positive, n=53). The potential prognostic factors, for example, T and N stage, preoperative carcinoembryonic antigen (CEA), postoperative (chemo) radiotherapy, operative methods, and several pathologic variables, were assessed among the three groups. The potential clinicopathologic factors were analyzed by using the Kaplan-Meier method, and the prognostic factors were compared in a Cox regression model. Also, we compared the oncologic results of 26 patients with a positive CRM (CMI) with those of the N1 and the N2 subgroups.
RESULTS
N2 patients had an impaired 5-yr local control rate (19.1%) compared with N0 (6.8%) and N1 (11.6%, P=0.029) patients after a median follow up of 60 months (range, 6 to 156 mo). Differences in disease-free and overall survival were also significantly different statistically among the three groups (84.0% and 85.2% for N0; 54.9% and 65.1% for N1; 37.3% and 49.8% for N2; P<0.001 both). The impact of NM on the local recurrence, disease-free survival and overall survival was confirmed in the regression model for the curatively resected patients. There were no significant differences in the recurrence and the survival rates between CMI and N2 stage.
CONCLUSION
NM has an independent prognostic impact on local failure and on disease-free survival and overall survival. Based on these findings, NM should be considered as an indicatior for adjuvant therapy. Although the prognostic impact of CMI is similar to that of N2, a larger prospective study is needed to clarify the prognostic association of CMI and N2.