Obesity and biliary tract cancers: Changing epidemiology.
Authors: Al Mahmasani Layal , Chou Joanne F. , Capanu Marinela , Srivastava Amitabh , Sigel Carlie S. , Alsuwailem Reem , Berger Michael F. , Khalil Danny N. , Harding James J. , O'Reilly Eileen M. , Abou-Alfa Ghassan K. 
Published: January 2025

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