Introduction: Tumor extent (T stage) and lymph node involvement (N stage) have a known combined negative effect on survival in patients with gallbladder adenocarcinoma, but the independent effects of these factors have been less well described. We investigated whether T stage and N stage independently predict survival after surgery for gallbladder adenocarcinoma.

Methods: We queried the Surveillance, Epidemiology and End Results database for patients treated with surgical resection for gallbladder adenocarcinoma between 1988 and 2004. Cases were stratified by disease severity based on tumor extent and nodal involvement. Kaplan-Meier and Cox regression methods were used to test the effect of disease severity and to develop multivariate models of the effects of demographic and clinical covariates on survival. Univariate and multivariate models were tested in the entire cohort and in a subsample with pathologically confirmed lymph node status.

Results: Four thousand and forty-eight patients who survived the immediate perioperative period comprised the full cohort. The subsample with pathologically confirmed lymph node status included 1298 patients. Age, gender, radiation treatment, tumor grade, tumor extent and lymph node status had statistically significant independent effects on survival in both models (all p<0.03). After accounting for T by N stage interactions, both tumor extent (1.21 < or = HR < or = 3.81, all p < or = 0.005) and lymph node involvement (1.80 < or = HR < or = 2.84, p<0.001) had independent effects on survival.

Conclusions: Tumor extent and lymph node metastases are independent predictors of survival after surgical resection for gallbladder adenocarcinoma. Tumor penetration of the gallbladder wall and pathologically confirmed lymph node involvement each carry poor prognosis.