Distal Cholangiocarcinoma and Pancreas Adenocarcinoma: Are They Really the Same Disease? A 13-Institution Study from the US Extrahepatic Biliary Malignancy Consortium and the Central Pancreas Consortium

Background Distal cholangiocarcinoma (DC) and pancreatic ductal adenocarcinoma (PDAC) are often managed as 1 entity, yet direct comparisons are lacking. Our aim was to use 2 large multi-institutional databases to assess treatment, pathologic, and survival differences between these diseases. Study Design This study included patients with DC and PDAC who underwent curative-intent pancreaticoduodenectomy from 2000 to 2015 at 13 institutions comprising the US Extrahepatic Biliary Malignancy and Central Pancreas Consortiums. Primary endpoint was disease-specific survival (DSS). Results Of 1,463 patients, 224 (15%) had DC and 1,239 (85%) had PDAC. Compared with PDAC, DC patients were less likely to be margin-positive (19% vs 25%; p = 0.005), lymph node (LN)-positive (55% vs 69%; p < 0.001), and receive adjuvant therapy (57% vs 71%; p < 0.001). Of DC patients treated with adjuvant therapy, 62% got gemcitabine alone and 16% got gemcitabine/cisplatin. Distal cholangiocarcinoma was associated with improved median DSS (40 months) compared with PDAC (22 months; p < 0.001), which persisted on multivariable analysis (hazard ratio 0.65; 95% CI 0.50 to 0.84; p = 0.001). Lymph node involvement was the only factor independently associated with decreased DSS for both DC and PDAC. The DC/LN-positive patients had similar DSS as PDAC/LN-negative patients (p = 0.74). Adjuvant therapy (chemotherapy ± radiation) was associated with improved median DSS for PDAC/LN-positive patients (21 vs 13 months; p = 0.001), but not for DC patients (38 vs 40 months; p = 0.62), regardless of LN status. Conclusions Distal cholangiocarcinoma and pancreatic ductal adenocarcinoma are distinct entities. Distal cholangiocarcinoma has a favorable prognosis compared with PDAC, yet current adjuvant therapy regimens are only associated with improved survival in PDAC, not DC. Therefore, treatment paradigms used for PDAC should not be extrapolated to DC, despite similar operative approaches, and novel therapies for DC should be explored.