Clinicopathologic factors and outcomes associated with lymph node retrieval in resectable colon cancer.

Abstract

3608 Background: A long-term determinant of survival in resectable colon cancer is the involvement of regional lymph nodes. The number of lymph nodes examined is a quality care measure and the American College of Pathology recommends 12 or more lymph nodes be examined. We evaluated the impact of this measure on survival and the clinicopathologic factors associated with lymph node retrieval. Methods: We conducted a retrospective analysis of 18,022 patients with resected stage I-III colon cancer in the Veteran's Affairs Central Cancer Registry between 1995 and 2008. The association between number of lymph nodes examined and overall survival was assessed using log-rank analysis. One-way analysis of variance was used to compare the differences between various groups. Results: The 5-yr survival rates for ≥12 lymph nodes vs. <12 lymph nodes are: Stage I (75% vs. 72%; p = 0.022), Stage IIA (64% vs. 55%; p < 0.001), Stage IIB (53% vs. 38%; p < 0.001) and Stage III (46% vs. 44%; p = 0.064). Mean number of lymph nodes retrieved increases with higher overall stage, higher T stage, age < 65 years, poorer differentiation and right- sided tumors (Table); no difference was seen between race. Patients with 12 or more lymph nodes retrieved has risen from 39% during 1995-1997 to 68% during 2006-2008 (p = 0.002). Conclusions: Younger patients, right-sided tumors, poorer differentiation, higher T and overall stage are associated with increased number of lymph nodes retrieved suggesting increased nodes may be related to host response to tumor. The 12 lymph node measure appears to be a positive prognostic variable and the VA has improved its compliance with this measure. No. of patients Mean no. of nodes ± std dev p value Overall stage p < 0.001 Stage I 5,998 9.6 ± 9.2 Stage IIA 5,755 13.5 ± 9.8 Stage IIB 682 13.2 ± 9.8 Stage III 5,587 14.8 ± 9.8 T stage p < 0.001 T1 3,323 7.8 ± 8.9 T2 3,901 11.8 ± 9.3 T3 10,004 14.2 ± 9.8 T4 794 15.5 ± 9.8 Age p < 0.001 ≥ 65 12,140 12.0 ± 9.4 < 65 5,882 13.6 ± 10.7 Race p = 0.522 Caucasian 14,416 12.5 ± 9.9 African American 3,200 12.7 ± 9.8 Site p < 0.001 Sigmoid 5,894 9.9 ± 9.1 Left 1,691 12.2 ± 10.5 Transverse 1,647 12.9 ± 10.4 Right 8,085 14.6 ± 9.7 Grade p < 0.001 Well diff 2,142 10.6 ± 9.3 Moderately diff 12,232 12.9 ± 9.7 Poorly diff 2,174 15.1 ± 10.6 No significant financial relationships to disclose.