Indications for extrahepatic bile duct resection due to perineural invasion in patients with gallbladder cancer

BACKGROUND: The indications for extrahepatic bile duct (EHBD) resection remain a major controversy in the surgical management of patients with gallbladder cancer. On the other hand, perineural invasion (PNI) was reported as an important factor in patients with gallbladder cancer because gallbladder cancer cells frequently spread to the tissues surrounding the EHBD via perineural routes. We assessed the correlation of PNI with clinicopathological factors in patients with gallbladder cancer to elucidate EHBD resection indications specifically in patients with PNI. METHODS: This retrospective study assessed the PNI status of 50 patients with gallbladder cancer who underwent curative resection and examined the correlation between the presence of PNI and clinicopathological factors. RESULTS: Thirteen patients (26%) were PNI positive. PNI was significantly correlated with male sex, proximal-type tumor, lymphatic and vascular invasion, and advanced T stage. Multivariate analysis found that PNI positivity (p < 0.001), lymphatic invasion (p = 0.007), and nodal stage (p < 0.001) were independent prognostic factors. PNI was never observed in patients with stage T1 cancer. Conversely, PNI was detected rarely in distal-type tumors, all of whom developed various types of recurrences. CONCLUSIONS: These results clearly demonstrated the prognostic impact of PNI in patients with gallbladder cancer. We suggest that EHBD resection in combination with cholecystectomy may not be useful for distal-type tumors from a perspective of PNI.