Characterization and clinical outcomes of rare biliary adenosquamous carcinoma

Data are scarce regarding biliary adenosquamous carcinoma (BASC) due to its low incidence. BASC displays a worse prognosis than adenocarcinoma and its specific treatment is still an unmet medical need. We conducted a description analysis of BASC including clinicopathologic parameters and treatment outcomes.

All consecutive patients with histologically proven BASC diagnosed in six French hospitals between 2000 and 2022 were enrolled and described.

A total of 16 BASC, accounting for 1.4 % of all biliary tract carcinoma, were included and the BASC incidence increased steadily over the past 22 years. The median age at diagnosis was 70.7 years (min-max 31.4-82.0 years) with most women (62.5 %). At diagnosis, half of BASC patients had a localized stage. The primary tumor locations were shared between gallbladder cancers (n = 7) and cholangiocarcinoma (n = 7), with mainly an extra-hepatic disease (71.4 %). Median overall survival was 9.5 months (95 % CI = 2.1-14.8 months). A total of 13 (81.6 %) patients had undergone surgery with a median relapse-free survival of 3.8 months (95 % CI = 0.0-10.5 months). Five (38.5 %) patients received an adjuvant chemotherapy. A total of seven (43.8 %) patients were treated with chemotherapy for the occurrence of metastases with a median progression-free survival of 2.8 months (95 % CI = 0.8-4.1 months). No objective response was observed and stable disease was achieved in two patients (28.6 %).

BASC is a rare disease with an increased incidence, highlighting the diagnostic challenges. BASC population was associated with a poor prognostic and limited therapeutic response. Further molecular investigations should be performed to investigate new therapeutic options.