Is a specific T classification needed for extrahepatic intraductal papillary neoplasm of the bile duct (IPNB) type 2 associated with invasive carcinoma?

Background: The necessity of a specific T classification for extrahepatic intraductal papillary neoplasm of the bile duct (IPNB) type 2, one of the precursors of cholangiocarcinoma (CC), remains unclear.

Methods: Patients who underwent resection for extrahepatic biliary tumors were reviewed. Relapse-free survival (RFS) was compared between IPNB type 2 and CC, stratified by T classification.

Results: The cohort involved 443 patients with IPNB type 2 (n = 57) and CC (n = 386). In 342 patients with perihilar tumors, 5-year RFS of IPNB type 2 and CC group was 49.8% versus 34.5% (p = .012), respectively. The RFS was 54.6% versus 47.2% (p = .110) for pT1-2 tumors and 28.6% versus 22.7% (p = .436) for pT3-4 tumors, respectively. In 92 patients with distal tumors, 5-year RFS was 47.4% versus 42.1% (p = .678). The RFS was 68.2% versus 49.6% (p = .422) for pT1 tumors and 18.8% versus 38.3% (p = .626) for pT2-3 tumors, respectively. Multivariate analysis identified that poor histologic grade (HR, 2.105; p < .001), microscopic venous invasion (HR, 1.568; p = .002), and nodal metastasis (HR, 1.547; p < .001) were independent prognostic deteriorators, while tumor type (IPNB type 2 vs. CC) was not.

Conclusions: Prognostic impact of IPNB type 2 was limited, suggesting unnecessity of a specific T classification for IPNB type 2 with invasive carcinoma.