Prognostic impact of lymph node retrieval and ratio in gastric cancer: A single-center U.S. experience.

Abstract

17 Background: Recommendations for extended lymphadenectomy in gastric cancer is thought to be associated with improved overall survival (OS), although defining adequate lymphadenectomy remains controversial. Methods: A single-institution, prospectively-maintained database of patients referred for surgical care of gastric cancer was reviewed. Patients were stratified by number of examined lymph nodes (eLN): <5, 6-10, 11-15, and >15 and positive LNs (LN+) stratified by 0, 1-2, 3-6, 7-15, and >15. Lymph node ratio (LN+:eLN) was evaluated, stratified by 0, 0.01-0.2, 0.21-0.5, and >0.5. Disease-free-survival (DFS) and OS were the primary endpoints, determined by Kaplan-Meier analyses. Results: From 1997-2012, 222 patients were included; most were male (N=122, 55%) with median age 67 (range 17-92) years. Of 220 (99%) patients surgically explored, 164 (74%) ultimately underwent resection. Median OS of the entire cohort was 22 months. Gender, ethnicity, and smoking status did not impact OS. Pathologic factors such as perineural invasion, lymphovascular invasion, and poor differentiation adversely affected OS, P<0.05. A median 14 lymph nodes (LN) were retrieved (range 0-45), with a median of one positive LN (range 0-31). No OS or disease-free survival (DFS) difference was observed when comparing <5, 6-10, 11-15, and >15 eLN, P=0.30. LN+ affected both OS and DFS: median OS was 52 months for 0 LN+ and decreased to 21 months with 1-2 LN+, 34 months 3-6 LN+, 25 months 7-15 LN+, and 11.5 months with >15 LN+. Similarly, median DFS decreased from 35 months with 0 LN+ to 19 months with 1-2 LN+, 9 months with 3-6 LN+, 13.5 months with 7-15 LN+, and 7.5 months with >15 LN+. Lymph node ratio demonstrated worse median OS with increasing ratio: 49 months for ratio of 0, 37 months for 0.01-0.2, 27 months for 0.21-0.5, and 12 months for >0.5, P<0.0001. DFS was similar: 35months for ratio of 0, 22 months for 0.01-0.2, 13 months for 0.21-0.5, and 7 months for >0.5, P<0.0001. Conclusions: Extent of lymphadenectomy does not impact OS or DFS. Presence of LN+ adversely impacts OS and DFS. Lymph node ratio may be a better prognostic indicator than number of eLN or LN+ in gastric cancer.