Wall-invasion Pattern Correlates with Survival of Patients with Gallbladder Adenocarcinoma

Gallbladder carcinomas (GBC) frequently show vascular invasion and metastasis when the carcinoma cells invade the perimuscular connective tissue (pT2 according to the TNM classification) through the muscular layer. In this study, two intramural invasion patterns were defined as (i) infiltrative growth (IG) type, infiltrative growth in the muscle layer without destruction and (ii) destructive growth (DG) type, massive growth with destruction of the muscle layer. Sixty-six surgically resected gallbladder adenocarcinomas invading the perimuscular connective tissue (pT2) and beyond the gallbladder wall, including the visceral serosa, (pT3/pT4) were examined. The overall survival rate of the patients with the DG type was significantly lower than that of the patients with the IG type (p=0.018). Lymphatic invasion (37.5% of IG and 62.5% of DG, p=0.014), venous invasion (41.9%, 58.1%, p=0.089), nodal status (30.4%, 69.6%, p=0.015) and scirrhous growth (INFy)(31.0%, 69.0%, p=0.0035) were more frequently detected in DG cases than in IG cases. In addition, median survival and survival rates were statistically analyzed. The patients with a high grade of lymphatic and venous invasion had lower survival rates (p<0.0001 and p<0.05, respectively). The patients with the DG type and scirrhous growth (INFy) also had lower survival rates (p<0.05 and p<0.0001, respectively) than did patients with the IG type and expansive/intermediate growth (INFα,β). On multivariate analysis, neural invasion (odds ratio, 0.157; 95% confidence interval, 0.039-0.629) was an independent predictor of mortality. In conclusion, the DG invasion pattern is an indicator of high malignant potential and indirectly worsens the prognosis of patients with gallbladder adenocarcinoma.