Tumor size as a prognostic indicator in colon cancer (CCa) patients undergoing sentinel lymph node mapping (SLNM) versus conventional surgery (CS) in National Cancer Data Base (NCDB).

Abstract

411 Background: Unlike other solid tumors, tumor size (TS) is not included in TNM staging for CCa. We correlated TS with TNM staging and 5-year overall survival (5yrOS) for patients (pts) who underwent SLNM vs CS in NCDB. Methods: A retrospectively review of 312 CCa pts undergoing SLNM compared to 298,021 CCa pts from NCDB undergoing CS between 1996 and 2010 was done. The maximum diameter of the primary tumor as TS, T and Nodal status were reviewed. Pts in each group was subdivided into 4 groups: (<2cm; 2-4cm; 4-6cm; >6cm). Data were analyzed using Spearman’s rho correlation and Kaplan-Meier for 5yrOS. Hazard ratios (HR) were calculated using a Cox model adjusting for age, sex, grade, T, N-status, and TNM stage. Results: Pts with TS <2 cm were mainly T1&T2 (80.7%, 74.8%), whereas for tumors >6cm, majority of pts were T3&T4 (93.2%, 88.8%). T1&T2 percentage consistently decreased as TS increased and T3&T4 percentage consistently increased with TS (Table). Nodal positivity according to tumor size for SLNM were 17%, 49%, 56%, 46% and for CS were 18%, 38%, 48%, 51%, respectively. In both groups, nodal positivity increased as TS increased. The overall nodal positivity in both groups was 46% and 42%. For SLNM and CS, overall survival decreased as TS increased. Overall SLNM pts had better OS when compared to CS pts (65%, 54%). Conclusions: Nodal +vity and overall survival where slightly better in SLMN pts. Vs CS pts. TS had +ve correlation with T staging and N status in 5 yr OS. Hence, TS may be considered a prognostic factor in CCa pts. [Table: see text]