Keika Hoshi

Objective: To examine associations between occupation and overall and site-specific cancer risk in Japan. Methods: We conducted a multicenter, hospital-based matched case–control study using the Inpatient Clinico-Occupational Survey of the Rosai Hospital Group (2005–2023), including 146,994 cancer cases and 278,244 matched controls. Conditional logistic regression was used to estimate sex-specific adjusted odds ratios by occupations. Results: Occupational disparities in cancer risk were observed, with more pronounced associations among men than women. Elevated risks were identified in manual and transport-related occupations, whereas lower risks were observed in selected professional occupations. Site-specific patterns varied by cancer type and sex. Conclusions: Occupation is associated with cancer risk in Japan, showing distinct sex-specific and site-specific patterns. These findings underscore the importance of occupational context in cancer epidemiology and provide a hypothesis-generating framework highlighting behavioral and detection-related factors.

Objectives: To investigate the association between occupation and Parkinson’s disease (PD) risk and whether patients with PD change occupation after onset. Design: A matched case–control study using secondary analysis of the Inpatient Clinico-Occupational Survey of the Rosai Hospital Group in Japan. Setting: A nationwide multicentre inpatient dataset in Japan from 2005 to 2021. Participants: The PD group comprised 2205 inpatients diagnosed with PD (International Statistical Classification of Diseases and Related Health Problems, 10th Revision code G20) and 10 436 matched controls without PD, matched for age, sex, year of admission and hospital. Primary outcome measure: Associations between the longest-held occupation—classified by industry (blue-collar, service, white-collar) and occupational class (blue-collar workers, service workers, professionals, managers)—and PD risk. Secondary outcome measure: Occupations and industries with increased PD risk; occupational changes before and after diagnosis among participants aged <60 years; and associations of PD risk with chemical exposure, smoking status and sex. Results: After adjustment for smoking and alcohol, professionals in the service (OR=2.01, 95% CI 1.24 to 3.25) and white-collar (OR=1.33, 95% CI 1.10 to 1.61) industries had higher PD risk than service workers. Doctors, dentists, veterinarians and pharmacists showed elevated risk. Among 160 PD patients, 47% were unemployed, 20% left voluntarily and 30% continued working after diagnosis. Chemical handling was not associated with PD risk after adjustment of multiple comparisons. Former or current smokers among blue-collar and service workers in blue-collar industry had a decreased risk of PD. Conclusions: Professionals in the service and white-collar industries, particularly those in healthcare occupations, had a higher risk of PD. Approximately 20% became unemployed after diagnosis.

Objectives While there is growing evidence that physical activity reduces the risk of hepatocellular carcinoma (HCC), the impact of occupational physical activity and sedentary behaviour remains unclear. This study aimed to investigate the associations between occupational physical activity and sedentary behaviour and HCC risk. Design Matched case-control study. Setting Nationwide multicentre, hospital-inpatient data set in Japan, from 2005 to 2021. Participants The study included 5625 inpatients diagnosed with HCC and 27 792 matched controls without liver disease or neoplasms. Participants were matched based on sex, age, admission date, and hospital. Primary measures The association between levels of occupational physical activity (low, medium, high) and sedentary time (short, medium, long) with the risk of HCC. Secondary measures Stratification of HCC risk by viral infection status (hepatitis B/C virus), alcohol consumption levels and the presence of metabolic diseases (hypertension, diabetes, dyslipidaemia, obesity). Results High occupational physical activity was not associated with HCC caused by hepatitis B/C virus infection in men. In women, high occupational physical activity was associated with a reduced risk of non-viral HCC, with ORs (95% CIs) of 0.65 (0.45–0.93). Among patients with non-viral HCC, medium occupational physical activity combined with medium alcohol intake further decreased the HCC risk in men with an OR of 0.70 (0.50–0.97), while high occupational physical activity combined with lowest alcohol intake decreased the HCC risk in women with an OR of 0.69 (0.48–0.99). Men and women with medium sedentary time had a lower HCC risk compared with those with long sedentary time, with ORs of 0.88 (0.79–0.98) in men and 0.77 (0.62–0.97) in women, respectively. In patients without viral infection or alcohol use, medium sedentary time reduced the HCC risk associated with fatty liver disease without comorbid metabolic diseases in women. Conclusions High levels of occupational physical activity and/or medium periods of sedentary time are associated with a reduced risk of HCC, particularly non-alcoholic steatohepatitis.

Objective: The aim of the study is to develop a job-exposure matrix for sedentary behavior and assess its relationship with noncommunicable diseases. Methods: We constructed a job-exposure matrix using occupational and industry classifications combined with data on daily average sitting durations from 41,718 individuals. This matrix was then applied to a cohort of 706,939 participants in a case-control study to explore the link between sedentary behavior and noncommunicable disease risks. Results: The matrix effectively identified sedentary behavior across different occupational groups. Using the matrix to assess sedentary behavior, associations were found between increased sedentary activity and heightened risks of diabetes, acute myocardial infarction, and endometrial cancer, while a reduced risk was observed for stroke. Conclusions: The job-exposure matrix provides valuable insights into the health impacts of sedentary behavior in the workplace, underscoring significant disease risks associated with prolonged inactivity.

Objectives In Japan, the risk of developing cancer among workers employed in workplaces where chemical substances are handled is unclear. This study aimed to assess the association between cancer risk and employment in workplaces handling hazardous chemicals. Methods The Inpatient Clinico-Occupational Survey of the Rosai Hospital Group data of 120 278 male patients with incident cancer and 217 605 hospital controls matched for 5-year age group, hospital (34 hospitals) and year of admission (2005–2019) were analysed. Cancer risk in relation to lifetime employment in workplaces using regulated chemicals was assessed while controlling for age, region and year of diagnosis, smoking, alcohol consumption and occupation. Further analysis stratified by smoking history was performed to examine interaction effects. Results In the longest group of employment in tertiles, ORs were increased for all cancers (OR=1.13; 95% CI: 1.07 to 1.19) and lung (OR=1.82; 95% CI: 1.56 to 2.13), oesophageal (OR=1.73; 95% CI: 1.18 to 2.55), pancreatic (OR=2.03; 95% CI: 1.40 to 2.94) and bladder (OR=1.40; 95% CI: 1.12 to 1.74) cancers. Employment of 1+ years was associated with risk for lung cancer; 11+ years for pancreatic and bladder cancers; and 21+ years for all cancers and oesophageal cancer. These positive relationships were particularly obvious among patients with a history of smoking; however, no significant interaction between smoking and length of employment was observed. Conclusions There is a high risk of cancer among workers, especially smokers, employed in workplaces handling regulated chemicals in Japan. Thus, future measures for chemical management in workplaces are needed to prevent avoidable cancers.

A person’s occupation may increase his/her risk for developing inflammatory bowel disease (IBD). This study investigated the association between risk for later-onset of IBD and both specific occupa...