Comparison of Waitlist Mortality Between Cholangiocarcinoma and Hepatocellular Carcinoma Liver Transplant Candidates.

BACKGROUND Despite the divergent disease biology of cholangiocarcinoma (CCA) and hepatocellular carcinoma (HCC), waitlist prioritization is identical for both diagnoses. METHODS We compared waitlist and post-transplant outcomes between CCA and HCC liver transplant patients with MELD exceptions using Scientific Registry of Transplant Recipients data. 408 CCA candidates listed between 2003 and mid-2017 were matched to two HCC cohorts by: listing date (±2 months, n=816), and OPTN region and date (±6 months, n=408). Cumulative incidence competing-risk regression examined the effects of diagnosis, OPTN region, and center-level CCA listing volume on waitlist removal due to death/being too ill (dropout). Cox models evaluated the effects of diagnosis, OPTN region, center-level CCA volume, and waiting time on graft failure among deceased donor liver transplant (DDLT) recipients. RESULTS After adjusting for OPTN region and CCA listing volume (all P≥0.07), both HCC cohorts had a reduced likelihood of waitlist dropout compared to CCA candidates (SHR≤0.63, 95%CI:0.41-0.93; P≤0.02). The cumulative incidence rates of waitlist dropout at 6 and 12 months were 13.2% (95%CI:10-17) and 23.9% (95%CI:20-29) for CCA candidates, 7.3% (95%CI:5-10) and 12.7% (95%CI:10-17) for HCC candidates with region and listing date matching, and 7.1% (95%CI:5-9) and 12.6% (95%CI:10-15) for HCC candidates with listing date matching only. Additionally, HCC DDLT recipients had a 57% reduced risk of graft failure compared to CCA recipients (P<0.001). Waiting time was unrelated to graft failure (P=0.57) and there was no waiting time by diagnosis cohort interaction effect (P=0.47). CONCLUSION When identically prioritized, LT candidates with CCA have increased waitlist dropout compared to those with HCC. More granular data are necessary to discern ways to mitigate this waitlist disadvantage and improve survival for patients with CCA.