Adenosquamous carcinoma of the gallbladder: a Bi-institutional experience in managing this rare entity.

Background: Adenosquamous Gallbladder Cancers (ASGBC) are rare variety of GBCs. Relative paucity of data with regards to the management of ASGBC exists.

Methods: Patients with diagnosis of ASGBC from January 2012 to March 2022 were categorised into 'Early', 'Locally advanced (LA)' and 'Metastatic (M)' ASGBC as per the predefined 'TMH Criteria'.

Results: A total of 196 patients included were categorised into early ASGBC (n = 19,9.7%), LA - ASGBC (n = 53,27%) and M - ASGBC (n = 124,63.3%) with median overall survival (OS) being worst for M - ASGBC (3.9 months) and best for early ASGBC (not reached). The 1-year and 3-year OS of LA-ASGBC patients who underwent surgery was significantly higher than those with non-surgical treatment (72.6%, 35.6% vs 25.1%, 0%, p <0.001). Although, the median OS of resected ASGBC was less as compared to resected gallbladder adenocarcinomas (GBACs) (40.8 vs. 56.1 months), it did not reach statistical significance (p=0.06). However, at higher stages of resected LA - ASGBC (Stage III), the median OS was significantly lower as compared to stage-matched resected GBACs (14.5 vs. 30.1 months, p= 0.006).

Conclusion: Multimodality treatment consisting of margin negative surgical resection with perioperative chemotherapy offers the best chance of long-term survival in ASGBC.