A comparison of competing lymph node staging schemes in resectable biliary cancer.

Abstract

166 Background: New schemes for lymph node (LN) staging have been proposed to improve upon the AJCC TNM cancer staging convention. We compared AJCC N0/N1 staging with the LN ratio and logarithmic odds systems in predicting overall survival (OS) in resectable biliary cancer patients, including cancer of the gallbladder, extrahepatic bile duct (EHBD), and ampulla of Vater (AOV). Methods: In a large, multiinstitutional U.S.-based biliary cancer data set, we identified 4,288 nonmetastatic resectable biliary cancer patients diagnosed between 1988 and 2006. We compared each subject's AJCC N stage with the two novel staging schemes. We split patients into two groups above or below the median for the two novel staging schemes and analyzed OS. Our comparison metric was the log-rank chi-squared statistic. As a baseline comparator, we included the median number of LNs resected. Results: Median (range) of follow- up was 2.5 years (1 month–19 years), with an overall median survival of 2.0 years (95% CI: 2.0–2.1 years). For all biliary patients combined, we found that the AJCC N0/N1 system and LN ratio schemes performed similarly. For gallbladder cancers (N= 1,340), LN ratio showed higher OS prediction utility, whereas in EHBD (N= 1,083) and AOV cancers (N= 1,865), AJCC staging was superior among competing methods. Conclusions: The LN ratio method is comparable with AJCC N staging for OS prediction, although the AJCC scheme is superior in two of three biliary cancers. We conclude that AJCC staging remains adequate for staging biliary cancers given the newer staging proposals. [Table: see text] No significant financial relationships to disclose.