Occupational inequalities in female cancer incidence in Japan: Hospital-based matched case-control study with occupational class

Abstract

BackgroundSocioeconomic inequalities in female cancer incidence have previously been undocumented in Japan.MethodsUsing a nationwide inpatient dataset (1984–2016) in Japan, we identified 143,806 female cancer cases and 703,157 controls matched for sex, age, admission date, and admitting hospital, and performed a hospital-based matched case-control study. Based on standardized national classification, we categorized patients’ socioeconomic status (SES) by occupational class (blue-collar, service, professional, manager), cross-classified by industry sector (blue-collar, service, white-collar). Using blue-collar workers in blue-collar industries as the reference group, we estimated the odds ratio (OR) for each cancer incidence using conditional logistic regression with multiple imputation, adjusted for major modifiable risk factors (smoking, alcohol consumption).ResultsWe identified lower risks among higher-SES women for common and overall cancers: e.g., ORs for managers in blue-collar industries were 0.67 (95% confidence interval [CI], 0.46–0.98) for stomach cancer and 0.40 (95% CI, 0.19–0.86) for lung cancer. Higher risks with higher SES were evident for breast cancer: the OR for professionals in service industries was 1.60 (95% CI, 1.29–1.98). With some cancers, homemakers showed a similar trend to subjects with higher SES; however, the magnitude of the OR was weaker than those with higher SES.ConclusionsEven after controlling for major modifiable risk factors, socioeconomic inequalities were evident for female cancer incidence in Japan.

Light to moderate amount of lifetime alcohol consumption and risk of cancer in Japan

“…A nationwide, multicentered, hospital‐based, matched case‐control study was conducted with the Inpatient Clinico‐Occupational Database of Rosai Hospital Group (ICOD‐R), which is administered by the Japan Organization of Occupational Health and Safety. Details of the ICOD‐R have been described elsewhere . Briefly, the Rosai Hospital Group consists of 33 general hospitals throughout Japan.…”

“…Each cancer case had a diagnosis with a specific cancer site (Table ). We defined cancer incidence as the first‐time admission among patients who did not have a previous history of cancer, and the validation for the diagnosis has been described elsewhere …”

“…All study subjects reported their average daily amount of standardized alcohol units and duration of drinking on admission to the hospital (or during their hospital stay due to their acute symptoms). One standardized drink containing 23 g of ethanol was equivalent to one 180‐mL cup (6 ounces) of Japanese sake, one 500‐mL bottle (17 ounces) of beer, one 180‐mL glass (6 ounces) of wine, or one 60‐mL cup (2 ounces) of whiskey . The duration of drinking accounted for the years from the age of starting drinking up to the age of quitting drinking or the age on admission if they had not quit drinking.…”

“…In sensitivity analyses, we estimated ORs and 95% CIs for men and women, current and former drinkers, and those who drank for <20, 20 to 39, and ≥40 years. In addition, we stratified analyses by occupational class (high vs low) because of occupational class inequalities in cancer risk . Furthermore, we restricted analyses to never smokers because of potential synergy effects of smoking and drinking .…”

Sex‐specific analysis of renal cell carcinoma histology and survival in Japan: A population‐based study 2004 to 2016

“…However, the incidence has been rising in recent years in Japan . Advanced imaging modalities, together with changes in lifestyle and behavioral risks (such as smoking, obesity, hypertension, and occupational stress), may underlie the increase in incidence …”