Obesity and biliary tract cancers: Changing epidemiology.

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643 Background: The incidence of biliary tract cancers (BTC) continues to rise (Sung et al. 2024). The reasons remain ill-defined. Over 70% of patients are diagnosed without identifiable predisposing factors. Obesity and overweight have emerged as putative contributors. We examined the epidemiologic and molecular characteristics of patients with BTC, with a focus on body mass index (BMI) at presentation and overall survival (OS). Methods: A retrospective cohort study of patients diagnosed with BTC at Memorial Sloan Kettering was conducted from January 2022 to December 2023. Patients were divided based on BMI into: obese (BMI≥30 kg/m 2 ) and non-obese (BMI<30 kg/m 2 ). We collected patients' baseline demographics, and results of somatic next generation sequencing using the MSK-IMPACT platform and compared between obese and non -obese groups using Fisher’s exact test for categorical and Wilcoxon rank sum test for continuous variables. OS was calculated from date of diagnosis, estimated using Kaplan-Meier methods and compared between groups using log rank test. Results: A total of 142 patients were identified. The table summarizes the baseline characteristics including age, BMI, sex, stage at diagnosis, family history, history of malignancy, and race. Obesity was significantly associated with family history of malignancy and white race. Among surviving patients (n=93), with a median follow-up of 13.8 months, 6-month, 1-year, and 2-year overall survival (OS) rates were 85% [95%CI: 80%-92%], 71% [95%CI: 64%-79%], and 54% [95%CI: 43%-68%] respectively. OS was not statistically different among obese and non-obese patients. However, when stratifying OS by BMI and gender, obese males were noted to have inferior OS compared to obese females (6-mo OS 75% and 90% respectively), though not statistically significant. Genetic sequencing did not reveal a specific molecular pattern in either group. Conclusions: Obesity appears not to be associated with young age, stage, or particular somatic alterations in this limited study. OS was not statistically different among obese and non-obese patients. Males with obesity appeared to have a worse prognosis. This observed gender-based difference needs to be further studied, and if confirmed further research is needed to explore potential factors that may explain the clinical observation. Baseline characteristics. Characteristics Overall n=142 Obese (BMI≥30 kg/m 2 ) n=54 Non-Obese (BMI<30 kg/m 2 )n=88 p-value Age 68 (35-91) 69 (35-87) 67 (36-91) >0.9 BMI (kg/m 2 ) 28.1 (16.6-48.5) 33.5 (30-48.5) 24.7 (16.6-29.6) Sex female/male 79 (56%)/63 (44%) 32 (59%)/22 (41%) 47 (53%)/41 (47%) 0.6 Stage Localized/advanced 21 (15%)/121 (85%) 11 (20%)/ 43 (80%) 10 (11%)/ 78 (89%) 0.3 Family history of cancer 91 (65%) 41 (76%) 50 (57%) 0.030 History of second malignancy 26 (18%) 12 (22%) 14 (16%) 0.4 Race White African Asian Other 99 (70%)12 (8.5%)20 (14%)11 (7.7%) 44 (81%)4 (7.4%)1 (1.9%)5 (9.3%) 55 (63%)8 (9.1%)19 (22%)6 (6.8%) 0.004