Association between shift work and the risk of death from biliary tract cancer in Japanese men

Tatsuhiko Kubo,Yingsong Lin,Yoshihisa Fujino,Shogo Kikuchi,Takeshi Nishiyama,Akiko Tamakoshi,Michiko Kurosawa

doi:10.1186/s12885-015-1722-y

Abstract

BackgroundThere is increasing evidence suggesting that shift work involving night work may increase cancer risk.MethodsWe examined the association between working rotating shifts and the risk of death from biliary tract cancer among Japanese men who participated in the Japan Collaborative Cohort Study. Of the 46,395 men recruited, 22,224 men aged 40–65 at baseline (1988–1990) who reported working full-time or were self-employed were included in the present analysis. The study subjects were followed through December 31, 2009. Information regarding occupation and lifestyle factors was collected using a self-administered questionnaire. Cox proportional hazard models were used to estimate the hazard ratio (HR) and 95 % confidence interval (CI) for the risk of death from biliary tract cancer in relation to shift work.ResultsDuring a mean 17-year follow-up, we observed 94 biliary tract cancer deaths, including 23 deaths from gallbladder cancer and 71 deaths from extrahepatic bile duct cancer. Overall, shift work was associated with a statistically non-significant increase in the risk of biliary tract cancer, with an HR of 1.50 (95 % CI: 0.81-2.77), among rotating shift workers. When the analysis was limited to extrahepatic bile duct cancer, a significant association appeared, with a multivariable-adjusted HR of 1.93 (95 % CI: 1.00-3.72) for rotating shift workers.ConclusionOur data indicate that shift work may be associated with increased risk of death from extrahepatic bile duct cancer in this cohort of Japanese men. The association with gallbladder cancer remains unclear because of the small number of deaths.

Highlights

There is increasing evidence suggesting that shift work involving night work may increase cancer risk
We observed a statistically non-significant increase in the risk of biliary tract cancer death associated with rotating shift work (Table 2)
After adjustment for potential confounding factors, the hazard ratio (HR) was 1.50 among rotating shift workers compared with daytime workers

Summary

Introduction

There is increasing evidence suggesting that shift work involving night work may increase cancer risk. Japan has a relatively higher incidence of biliary tract cancer compared with other developed countries [2]. Workers engaging in petroleum refining, paper milling, chemical processing, and shoemaking were found to have an increased risk of gallbladder cancer development [6]. Another occupation-related factor that has wide implications for public health is shift work. 1520 % of the working population in industrialized countries is estimated to engage in night-shift work [9], and the effect of such a work schedule on health, including on the formation of cancers, has attracted increasing multidisciplinary

Methods

Results

Discussion

Conclusion