Adeno-squamous and squamous cell carcinoma of the gallbladder: The importance of histology in surgical management.

BACKGROUND: Although gallbladder adenocarcinoma (AC) is potentially curable with resection, outcomes of squamous histologies are poorly described. METHODS: We retrospectively analyzed all gallbladder cancers which underwent resection-for-cure in our health system from 2007 to 2017. We compared outcomes of AC to adeno-squamous (ASC)/squamous (SC) histologies. RESULTS: 91 patients met criteria; 76 AC, 15 ASC/SC. Compared to AC, ASC/SC tumors were larger (58 vs. 28 mm), with more frequent liver invasion (73% vs. 37%), pN+ (60% vs. 32%), higher stage (III/IV 73% vs. 52%), and displayed more LVI (60% vs. 36%), p < 0.05. For stage III/IV disease, provided R0 was achieved, survival was durable and similar for ASC/SC and AC (OS median 28mo ASC/SC vs. 25mo AC, p = 0.132; PFS median 21mo ASC/SC vs. 13mo AC, p = 0.206). Pure SC had considerably poorer median OS (<5mo) than ASC (23mo) and AC (28mo). DISCUSSION: Squamous variants of gallbladder cancer confer aggressive and advanced disease and often require more radical resections to achieve R0. Durable survival is possible in ASC provided R0 is achieved. Pure SC has dismal survival even with R0 resection.