Obesity is associated with biliary tract cancer mortality and incidence: A pooled analysis of 21 cohort studies in the Asia Cohort Consortium

Isao Oze, Hidemi Ito, Yuriko N. Koyanagi, Sarah Krull Abe, Md Shafiur Rahman, Md Rashedul Islam, Eiko Saito, Prakash C. Gupta, Norie Sawada, Akiko Tamakoshi, Xiao Ou Shu, Ritsu Sakata, Reza Malekzadeh, Ichiro Tsuji, Jeongseon Kim, Chisato Nagata, San Lin You, Sue K. Park, Jian Min Yuan, Myung Hee ShinSun Seog Kweon, Mangesh S. Pednekar, Shoichiro Tsugane, Takashi Kimura, Yu Tang Gao, Hui Cai, Akram Pourshams, Yukai Lu, Seiki Kanemura, Keiko Wada, Yumi Sugawara, Chien Jen Chen, Yu Chen, Aesun Shin, Renwei Wang, Yoon Ok Ahn, Min Ho Shin, Habibul Ahsan, Paolo Boffetta, Kee Seng Chia, You Lin Qiao, Nathaniel Rothman, Wei Zheng, Manami Inoue, Daehee Kang, Keitaro Matsuo

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


Body fatness is considered a probable risk factor for biliary tract cancer (BTC), whereas cholelithiasis is an established factor. Nevertheless, although obesity is an established risk factor for cholelithiasis, previous studies of the association of body mass index (BMI) and BTC did not take the effect of cholelithiasis fully into account. To better understand the effect of BMI on BTC, we conducted a pooled analysis using population-based cohort studies in Asians. In total, 905 530 subjects from 21 cohort studies participating in the Asia Cohort Consortium were included. BMI was categorized into four groups: underweight (<18.5 kg/m2); normal (18.5-22.9 kg/m2); overweight (23-24.9 kg/m2); and obese (25+ kg/m2). The association between BMI and BTC incidence and mortality was assessed using hazard ratios (HR) and 95% confidence intervals (CIs) by Cox regression models with shared frailty. Mediation analysis was used to decompose the association into a direct and an indirect (mediated) effect. Compared to normal BMI, high BMI was associated with BTC mortality (HR 1.19 [CI 1.02-1.38] for males, HR 1.30 [1.14-1.49] for females). Cholelithiasis had significant interaction with BMI on BTC risk. BMI was associated with BTC risk directly and through cholelithiasis in females, whereas the association was unclear in males. When cholelithiasis was present, BMI was not associated with BTC death in either males or females. BMI was associated with BTC death among females without cholelithiasis. This study suggests BMI is associated with BTC mortality in Asians. Cholelithiasis appears to contribute to the association; and moreover, obesity appears to increase BTC risk without cholelithiasis.

Original languageEnglish
Pages (from-to)1174-1190
Number of pages17
JournalInternational Journal of Cancer
Issue number7
StatePublished - 1 Apr 2024
Externally publishedYes


  • Asia Cohort Consortium
  • biliary tract cancer
  • body mass index
  • obesity
  • pooled analysis


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