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

Association Between Alcohol Consumption Patterns and Glaucoma in Japan

PRCIS

In this case-control study of the Japanese population, including 3207 glaucoma cases, alcohol consumption patterns such as frequency and quantity showed a positive association with glaucoma prevalence.

PURPOSE

To examine the association between alcohol consumption patterns and glaucoma.

SUBJECTS AND METHODS

This case-control study evaluated 3207 cases with glaucoma and 3207 matched controls. Patients over 40 years of age were included from 1,693,611 patients admitted to 34 hospitals in Japan. Detailed alcohol consumption patterns (drinking frequency, average daily drinks, and total lifetime drinks) were obtained, as well as various confounding factors, including smoking history and lifestyle-related comorbidities. Conditional logistic regression models were used to calculate odds ratios (ORs) and 95% CIs for glaucoma prevalence.

RESULTS

Drinking frequency showed an association with glaucoma for "a few days/week" (OR, 1.19; 95% CI, 1.03-1.38) and "almost every day/week" (OR, 1.40; 95% CI, 1.18-1.66). Average daily drinks showed an association for ">0-2 drinks/day" (OR, 1.16; 95% CI, 1.03-1.32). Total lifetime drinks showed an association for ">60-90 drink-year" (OR, 1.23; 95% CI, 1.01-1.49) and ">90 drink-year" (OR, 1.23; 95% CI, 1.05-1.44). As alcohol consumption levels differed considerably between men and women, additional analyses were conducted separately for men and women. Among men, drinking frequency of "a few days/week" and "almost every day/week," average daily drinks of ">0-2 drinks/day" and ">2-4 drinks/day," and total lifetime drinks of ">60-90 drink-year" and ">90 drink-year" had an association with glaucoma. Conversely, among women, neither drinking frequency, average daily drinks, nor total lifetime drinks were associated.

CONCLUSIONS

Both the frequency and quantity of alcohol consumption were associated with glaucoma. Further research on gender differences is warranted.

Length of employment in workplaces handling hazardous chemicals and risk of cancer among Japanese men

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.

Volume-Outcome Relationship in Cancer Survival Rates: Analysis of a Regional Population-Based Cancer Registry in Japan

BACKGROUND

There is limited data on the relationship between hospital volumes and outcomes with respect to cancer survival in Japan. The primary objective of this study was to evaluate the effect of hospital volume on cancer survival rate using a population-based cohort database.

METHODS

Using the Kanagawa cancer registry, propensity score matching was employed to create a dataset for each cancer type by selecting 1:1 matches for cases from high- and other-volume hospitals. The 5-year survival rate was estimated and the hazard ratio (HR) for hospital volume was calculated using a Cox proportional hazard model. Additional analyses were performed limited to cancer patients who underwent surgical operation, chemotherapy, and other treatments in each tumor stage and at the time of diagnosis.

RESULTS

The number of cases with complete data, defined as common cancers (prostate, kidney, bladder, esophagus, stomach, liver, pancreas, colon, breast, and lung), was 181,039. Adjusted HR differed significantly among hospital volume categories for the most common cancers except bladder, and the trends varied according to cancer type. The HR ranged from 0.76 (95%CI, 0.74-0.79) for stomach cancer to 0.85 (0.81-0.90) for colon cancer.

CONCLUSIONS

This study revealed that a relationship may exist between hospital volume and cancer survival in Japan.

Occupational class and risk of hepatitis B and C viral infections: A case-control study-based data from a nationwide hospital group in Japan

BACKGROUND

Occupational class, a proxy for socio-economic status, is a known factor for health disparities. However, no study has reported the association between occupational class and the risk of viral hepatitis B and C (HBV/HCV) infections. We investigated the effects of occupational class on the prevalence of HBV/HCV infections.

METHODS

This is an unmatched hospital-based case-control study that included 12,101 patients who were diagnosed with HBV infection (ICD-10, B16.0, B16.1, B16.2, B16.9, B17.0, B18.0, B18.1) or HCV infection (ICD-10, B17.1, B18.2) and 698,168 controls (those with non-HBV/HCV-related diseases) aged ≥ 20 years who were initially hospitalized between 2005 and 2019. Patients were categorized according to occupational class (blue-collar, service, professional, and manager) and industrial sector (blue-collar, service, and white-collar). Managers in the blue-collar industry were set as the reference group, and the odds ratios (ORs) for the risk of HBV and HCV infections were calculated.

RESULTS

Occupational class was significantly associated with only HCV infection risk. Professionals in all industrial sectors showed the lowest risk for HCV (OR (95% confidence intervals [CIs]) = 0.69 [0.58-0.82] in the blue-collar industry, 0.52 [0.38-0.73] in the service industry, and 0.60 [0.52-0.70] in the white-collar industry). Further, after adjusting for sex, age, and region of admitting hospital, all occupational classes in the white-collar industry showed lower risks of HCV than those in the other industries (ORs= 0.58 [0.47-0.71] in blue-collar workers, 0.74 [0.64-0.84] in service workers, 0.60 [0.52-0.70] in professionals, and 0.81 [0.64-1.02] in managers in white-collar industry).

CONCLUSIONS

Occupational class was closely associated with HCV infection risk only. Considering that blue-collar workers in the white-collar industry also showed a low risk, adequate measures should be taken against hepatitis, possibly because of the screening tests and cure implemented in that population.

Alcohol use patterns and risk of incident cataract surgery: a large scale case-control study in Japan

To examine the risk of incident cataract surgery associated with alcohol use patterns among Japanese adults. This was a case-control study evaluating 14,861 patients with incident cataract surgery and 14,861 matched controls. Subjects admitted to any of the 34 hospitals in Japan and aged between 40 and 69 years were included. Drinking patterns (drinking frequency, daily average drinks, and total amount of lifetime drinking), smoking history, lifestyle-related comorbidities, and occupational factors were surveyed by trained interviewers. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using conditional logistic regression models. For drinking frequency, ORs in the 1-3 days/week and 4-7 days/week groups were 1.10 (95% CI 1.03-1.17) and 1.30 (1.21-1.40), respectively. For average drinks, ORs in > 0-2 drinks/day, > 2-4 drinks/day, and > 4 drinks/day were 1.13 (1.06-1.20), 1.23 (1.12-1.35), and 1.16 (1.03-1.31), respectively. Both men and women had an increased risk of incident cataract surgery with increased total lifetime drinking, with a significant increase in risk occurring at > 90 drink-years for men and > 40 drink-years for women. A positive dose-response relationship was observed between alcohol consumption and cataract. Restricted drinking may help to reduce the progression of cataracts.

Occupation- and industry-specific cancer mortality among Japanese women from 1980 to 2015

BACKGROUND

The number of women in Japan who continue working after childbirth is on the rise. Over the past few years, Japan's cancer mortality rate has increased. About 50% of all cancer deaths among Japanese women aged 25-64 are caused by lung, gastric, pancreatic and colorectal cancers. This study aims to examine the difference in mortality risk for key cancers among women and explore the effect of the economic crisis in the mid-1990s separately for occupational and industrial categories.

METHODS

Data from 1980 to 2015 were gathered from the Japanese Population Census and National Vital Statistics conducted in the same year. A Poisson regression analysis was used to estimate mortality risk and mortality trends for lung, gastric, pancreatic and colorectal cancer among Japanese working women aged 25-64 years.

RESULTS

Across most industrial and occupational groups, the trends in age-standardised cancer mortality rate for women have declined. Workers in management, security and transportation have a higher cancer mortality risk than sales workers. The risk of death from all four cancers is higher for workers in the mining and electricity industries than for wholesale and retail workers.

CONCLUSION

To improve the health and well-being of employed Japanese women, it is crucial to monitor cancer mortality trends. Using these population-level quantitative risk estimates, industry- and occupation-specific prevention programmes can be developed to target women at higher cancer risk and enable the early detection and treatment of cancer.

Changes in cause-specific mortality trends across occupations in working-age Japanese women from 1980 to 2015: a cross-sectional analysis

Background

Reducing health inequalities is an important public health challenge. Many studies have examined the widening health gap by occupational class among men, but few among women. We therefore estimated variation in absolute and relative mortality by occupational category across four leading causes of mortality—cancer, ischaemic heart disease, cerebrovascular disease, and suicide—to explore how occupational class is associated with health among working women aged 25–64 in Japan.

Methods

We conducted a repeated cross-sectional study using Poisson regression analysis on each five-yearly mortality data from 1980 to 2015, obtained from the National Vital Statistics and the Japanese Population Census.

Results

There was a decreasing trend in mortality from all cancers, ischaemic heart disease, cerebrovascular disease, and suicide among women in all occupational groups from 1980 to 2015. Agriculture workers had higher risk of mortality than professional workers for all four causes of death. The absolute difference in mortality rates for all cancers and cerebrovascular disease was higher in 2000–2015 than 1980–1995. The mortality trend among clerks and sales workers decreased after 2000, except for suicide.

Conclusions

Mortality rates from all four causes are higher among agriculture workers compared to professional workers, and attention is needed to reduce this mortality gap. Continuous monitoring of ongoing mortality trends is essential to ensure better health and wellbeing in Japan.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12905-022-01621-4.

Occupational disparities in tumor grade and cytosolic HMGB1 expression in renal cell cancer

Objectives

We sought to examine occupational disparities in tumor grade and cytosolic expression of high‐mobility group box‐1 (HMGB1) among renal cell cancer (RCC) patients.

Methods

This retrospective study included 318 RCC patients with complete information on occupation and pathology in Kanagawa Cancer Registry (KCR). Longest‐held occupations were grouped into manual workers (e.g., manufacturing, construction) versus “others.” Odds ratios (OR) and 95% confidence intervals (CI) for high‐grade histology were estimated by logistic regression, adjusted for age and sex. We also examined a sub‐sample of 74 low‐grade RCC inpatients to estimate the OR for positive cytosolic HMGB1 expression in manual workers, adjusting for age, sex, and other available covariates.

Results

High‐grade tumors were more prevalent in manual workers compared to other occupations: 23.0% (14/61) versus 10.9% (28/257, p = .01) with an adjusted OR of 2.28 (95% CI, 1.11–4.69). In the sub‐sample of low‐grade RCCs, positive cytosolic HMGB1 expression was more prevalent in manual workers compared to other occupations: 71.4% (10/14) versus 38.3% (23/60, p = .03) with a sex‐ and age‐adjusted OR of 3.76 (95% CI, 1.03–13.7).

Conclusions

Manual workers are associated with increased risks of high‐grade renal cell tumors and cytosolic HMGB1 expression.

Breast Cancer Risk Among Female Health Professionals: A 35-Year Population-Based Longitudinal Cohort Study in Taiwan

INTRODUCTION

Breast cancer is the most frequently diagnosed cancer among women worldwide. Previous studies have found a higher risk in nurses but no clear relationship among other health professionals. This study aims to investigate the risks of incident breast cancer among female health professionals compared with that among nonhealth professionals in Taiwan.

METHODS

This longitudinal observational cohort study included >35 years (1979-2016) of data from 4 nationwide population-based databases in Taiwan and identified matched cohorts with 1-to-2 propensity score matching between 277,543 health professionals and 555,086 nonhealth professionals. This study calculated total person-years for study subjects and compared breast cancer incidence between matched health and nonhealth professionals. Multivariable Cox proportional hazards and competing risk analyses were used, stratified by birth age, job tenure categories, and types of health professional license. Statistical analyses were conducted in 2019-2020.

RESULTS

Health professionals had a significantly higher risk of breast cancer (hazard ratio=1.34, 95% CI=1.28-1.41; subdistribution hazard ratio=1.36, 95% CI=1.30, 1.42). Elevated risk of breast cancer incidence was associated with birth age, job tenure, and several health professional license types, including physician, pharmacist, registered nurse, midwife, medical technologist, and psychologist.

CONCLUSIONS

Elevated breast cancer risk was found overall in female health professionals. Regular ultrasonography for younger women and mammography for those aged >45 years may be necessary in the annual labor physical examination for female health professionals.

Occupational socioeconomic risk associations for head and neck cancer in Europe and South America: individual participant data analysis of pooled case-control studies within the INHANCE Consortium

BACKGROUND

The association between socioeconomic disadvantage (low education and/or income) and head and neck cancer is well established, with smoking and alcohol consumption explaining up to three-quarters of the risk. We aimed to investigate the nature of and explanations for head and neck cancer risk associated with occupational socioeconomic prestige (a perceptual measure of psychosocial status), occupational socioeconomic position and manual-work experience, and to assess the potential explanatory role of occupational exposures.

METHODS

Pooled analysis included 5818 patients with head and neck cancer (and 7326 control participants) from five studies in Europe and South America. Lifetime job histories were coded to: (1) occupational social prestige-Treiman's Standard International Occupational Prestige Scale (SIOPS); (2) occupational socioeconomic position-International Socio-Economic Index (ISEI); and (3) manual/non-manual jobs.

RESULTS

For the longest held job, adjusting for smoking, alcohol and nature of occupation, increased head and neck cancer risk estimates were observed for low SIOPS OR=1.88 (95% CI: 1.64 to 2.17), low ISEI OR=1.74 (95% CI: 1.51 to 1.99) and manual occupations OR=1.49 (95% CI: 1.35 to 1.64). Following mutual adjustment by socioeconomic exposures, risk associated with low SIOPS remained OR=1.59 (95% CI: 1.30 to 1.94).

CONCLUSIONS

These findings indicate that low occupational socioeconomic prestige, position and manual work are associated with head and neck cancer, and such risks are only partly explained by smoking, alcohol and occupational exposures. Perceptual occupational psychosocial status (SIOPS) appears to be the strongest socioeconomic factor, relative to socioeconomic position and manual/non-manual work.

The relationship of hospital stay and readmission with employment status

The Inpatient Clinico-Occupational Survey collected data from 3.76 million patients, showing that the average length of stay declined by 16.1 d in FY2008 and by 14.1 d in FY2015. In this study, we assessed the length of hospital stay and readmission, stratified by ICD-10 and employment status. A cross-sectional study was conducted on data from FY2008, including those from 65,806 first hospitalizations and 16,653 readmissions in FY2008, where 62,260 first admissions and 29,242 readmissions in FY 2015. The length of hospital stay was longest in those admitted due to external influences (24.8 d), followed by musculoskeletal disorders (22.5 d). This remained unchanged in FY2015, however, lengths of stay of those were reduced by 20.1 and 20.0 d, respectively. The length of hospital stay for most diseases was longer upon readmission than on first admission, and longer for those who were unemployed. It is necessary to give attention to patients who need to be discharged early due to work, or plan for frequent hospitalization in order to reduce the length of each hospital stay because of the expected increase in the number of elderly workers brought on by a declining birth rate and an aging population.

Analysis of Predictors of Breast Cancer Screening among Japanese Women using Nationally Representative Survey Data, 2001-2013

Objective:

Predictors of participation in breast cancer screening in recent years or the trend of participation rate by predictors over the years has not been investigated in Japan. In this study, we investigated predictors for participation in breast cancer screening and analyzed the trend of participation rate depending on the predictors using nationally representative survey data in Japan.

Methods:

The data of “Comprehensive Survey of Living Conditions” in Japan from 2001 to 2013 were used. Participation in breast cancer screening was used as an outcome. Next, as explanatory variables, we used age group, marital status, living arrangements, educational level, household income, employment status, smoking status, regular outpatient visit status, and self-rated health status. Then, the participation rate for breast cancer screening was calculated for each of the factors over the years. In addition, multivariate logistic regression analysis was conducted to analyze the association between each factor and the participation rate using data from 2010 and 2013.

Results:

We found that non-married women, women with lower educational level, women with low household income, self-employed or unemployed women, smokers, and women with low self-rated health status were significantly less likely to participate in breast cancer screening. Conversely, the participation rate increased for all predictor groups from 2001 to 2013, and the increase in the participation rate for never-married women was particularly evident compared with the other marital statuses. However, significant differences in the participation rate for breast cancer screening existed depending on marital status, household income, employment status, and smoking status throughout the analyzed years.

Conclusion:

Our findings suggest that further recommendations for breast cancer screening are particularly needed among women of low socioeconomic status and those who are self-employed or unemployed to increase the participation rate in Japan.

Gastric cancer mortality rates by occupation and industry among male and female workers aged 25-64 years in Japan

Differences in risk for gastric cancer exist among occupations and industries in Japan. Using a 2015 national dataset, we estimated the mortality rates due to gastric cancer in Japanese male and female workers aged 25-64 yr. Regression models were used to estimate the mortality rate ratios separately for men and women with adjustment for age. The occupation with the highest risk ratio was "Service" in men (2.06, 95% confidence interval: 1.63-2.61) and "Construction and Mining" in women compared with "Sales". For industries, workers in "Mining", "Electricity, Gas, Heat supply and Water", "Fisheries", "Agriculture and Forestry", and "Construction" had a higher mortality risk. Our results showed that occupations and industries with higher mortality rates in men had the same trend as the results from 2010, and occupations and industries with higher mortality rates in women were almost the same as those in men. The analyses also indicated that managerial and professional workers in Japan had higher mortality as opposed to developed Western countries. In conclusion, this study suggests that occupations and industries still impact men and women's health in terms of mortality due to gastric cancer in Japan.

Analysis of the difference in the perinatal mortality rate between white-collar and blue-collar workers in Japan, 1995-2015

OBJECTIVES

This study investigated differences in the perinatal mortality rate between white-collar and blue-collar workers.

METHODS

Data from the “Report of Vital Statistics: Occupational and Industrial Aspects” in Japan covering the period from 1995 to 2015 were used. Five-year maternal age groups from 15-19 years to 45-49 years were analyzed according to work type, and the perinatal mortality rate for each age group and the age-standardized perinatal mortality rate according to maternal age were calculated in each analyzed year. A Bayesian age-period-cohort analysis was used to estimate age, period, and cohort effects for the perinatal mortality rate according to work type. Moreover, the perinatal mortality rate ratios between types of workers were estimated for each age group, period, and cohort.

RESULTS

The estimated perinatal mortality rate ratios of blue-collar to white-collar workers were above 1 in most of the age groups and cohorts. The age effect for the perinatal mortality rate among white-collar workers was the largest in the 15-year to 19-year age group, whereas that among blue-collar workers was the largest in the 45-year to 49-year age group. Furthermore, the estimated perinatal rate ratio between white-collar and blue-collar workers tended to increase with maternal age. The magnitude of the decrease of the cohort effects on the perinatal mortality rate was rather larger in blue-collar workers in the cohorts born between 1946-1950 and 1996-2000.

CONCLUSIONS

The magnitude of the disparity markedly increased with maternal age. Thus, middle-aged blue-collar workers need more prenatal care and preventive measures for perinatal mortality than white-collar workers.

A comparison of the burden of lung cancer attributable to tobacco exposure in China and the USA

Background

Tobacco exposure (TE) is the major contributor to lung cancer mortality worldwide. This study aims to clarify the possible reasons underlying the long-term trends and differences in lung cancer mortality attributable to TE in China and the United States of America (USA).

Methods

Lung cancer mortality data from China and the USA were obtained from the Global Burden of Disease (GBD) Study 2017. Joinpoint regression analysis was used to assess the magnitude and direction of trends from 1990 to 2017, and the age-period-cohort model (APCM) was used to analyze the temporal trends of lung cancer mortality by age, period, and cohort.

Results

For lung cancer attributable to smoking, the age-standardized mortality rates (ASMRs) exhibited an upward trend in China and a downward trend in the USA. The overall net drifts per year were 0.72% for China and -3.03% for the USA, and the local drift values in China and the USA increased by age group. All cohort/period relative risks (RRs) increased in China but decreased in the USA. The longitudinal age curves increased rapidly in China, whereas those in the USA were rose gradually. For lung cancer attributable to secondhand smoke, the ASMRs showed a downward trend in both China and the USA. The overall net drifts per year were -0.48% for China and -3.97% for the USA, and the local drift values in China and the USA also increased by age group. Cohort/period RRs decreased in the USA, and fluctuated in China. The longitudinal age curve trends in China and the USA were similar to those of smoking.

Conclusions

The dangers of TE in China remain serious. The rates of lung cancer mortality attributable to TE have increased, especially in older individuals. We recommend that China strengthens the implementation of effective targeted tobacco control policies and other interventions to reduce the burden of lung cancer.

Recent Increasing Incidence of Early-Stage Cervical Cancers of the Squamous Cell Carcinoma Subtype among Young Women

Few studies have reported on the increase in cervical cancer incidence in Japan. We aimed to determine the relevant trends in the metropolitan regions of Japan and to identify the population with the highest risk, based on histological subtype, cancer stage, and diagnostic processes. Using population-based data (2009–2013), we identified 2110 women, aged ≥20 years, with cervical cancer. We estimated the age-standardized and age-specific incidence rates of cervical cancer for the study period based on the 1985 national model population. The average annual percent change (AAPC) and 95% confidence interval (CI) were calculated using the joinpoint regression analysis. We stratified the analyses based on histological subtypes, stage, and diagnostic process via cancer screening. The increase in the overall age-standardized incidence was not significant. However, the increase was significant for women aged 30–39 years (AAPC 20.0%/year, 95% CI: 9.9–31.1), which was attributable to the increase in the incidence of the squamous cell carcinoma (SCC) subtype (AAPC 23.1%/year, 95% CI: 10.7–36.8). Among younger women, aged <50 years, further stratification showed an increase in the undiagnosed early-stage SCC subtype via cancer screening. In Japan, the incidence of HPV-related cervical cancer has been increasing in undiagnosed younger women.

Combined effects of occupational exposure to hazardous operations and lifestyle-related factors on cancer incidence

We aimed to examine whether the number of types of hazardous operations at work experienced through a lifetime is associated with cancer incidence, and additionally examined the combined effects with lifestyle‐related factors. Using a nationwide, multicenter, hospital inpatient dataset (2005‐2015), we conducted a matched case‐control study with 1 149 296 study subjects. We classified the participants into those with none, 1, or 2 or more types of hazardous operation experience, based on information of special medical examinations taken, mandatory in Japan for workers engaged in hazardous operations. Using those with no experience as the reference group, we estimated the odds ratios for cancer incidence (all sites, lung, stomach, colon and rectum, liver, pancreas, bile duct, and bladder) by conditional logistic regression with multiple imputations. We also examined the effects of the combination with hazardous operations and lifestyle‐related factors. We observed increased risks for cancer of all sites, and lung, pancreas, and bladder cancer associated with the experience of hazardous operations. Multivariable‐adjusted ORs (95% CIs) of cancer incidence of all sites were 1 (reference), 1.16 (1.12, 1.21), and 1.17 (1.08, 1.27) for none, 1, and 2 or more types of hazardous operation experience, respectively (P for trend <.001). Potential combined associations of hazardous operations with smoking were observed for lung, pancreas, and bladder cancer, and with diabetes for pancreas cancer. Engaging in hazardous operations at work and in combination with lifestyle‐related factors may increase the risk of cancer. We highlight the potential for those engaged in hazardous work to avoid preventable cancers.

Manufacturing Industry Cancer Risk in Japan: A Multicenter Hospital-Based Case Control Study

Background:

It is well known that specific occupations can cause harm in developing malignant neoplasms. Chemical exposure is particularly high in the manufacturing industry and workers in this sector may face a higher occupational risk for cancer. We aimed to estimate inequalities in the risk of cancers related to occupational chemical exposure in various manufacturing categories.

Methods:

Using nationwide clinical inpatient data (1984−2017) in Japan, we undertook a multicenter, case-control study with regard to risks of developing cancers among various manufacturing industry categories. Using the food manufacturing industry as the reference group, odds ratios and 95% confidence intervals for each industry were estimated by conditional logistic regression, adjusted for sex, age, admission period, and the admitting hospital. Medical record summaries accounting for 89% of industrial categories with high odds ratios were collected to confirm diagnoses made on the basis of histology. We estimated industrial hazards based on the Pollutant Release and Transfer Register.

Results:

A reduced risk for some of common cancers was observed among lumber and wood products industries. Leather tanning, leather products and fur tended to show a higher risk: 2.36 (95% CI 1.15−4.83) for pancreatic cancer, 2.85 (95% CI 1.26−6.47) for liver cancer and 2.00 (95% CI 1.01–3.99) for lung cancer. For the electronics category, observations of high risk ranged from 2.09 (95%CI 1.18–3.70) for ureter cancer, to 2.49 (95% CI 1.79–3.55) for kidney cancer.

Conclusions:

This study revealed industry risk inequalities in manufacturing categories were present with regard to the risk of common cancers in Japan.

Investigating the health disparities in the association between lifestyle behaviors and the risk of head and neck cancer

Many studies have reported a positive association between lower socioeconomic status (SES) and higher head and neck cancer (HNC) risk. Fewer studies have examined the impact of SES on the association between alcohol or cigarette use and HNC risk. The current case‐control study (1104 HNC cases and 1363 controls) investigated the influence of education, a SES indicator, on the association between HNC and the use of alcohol, cigarettes, or betel quids in Taiwan, a country with universal health care. Our results showed a larger increase in HNC risk associated with alcohol among those with lower educational level (odds ratio [OR] = 2.07; 95% confidence interval [CI], 1.53‐2.80) than those with higher educational level (OR = 1.38; 95% CI, 1.04‐1.85) (heterogeneity‐P = .03). Educational level had an influence on the association between alcohol use and HNC risk among those with genetic susceptibility (ALDH2‐deficient) to the carcinogenic effect of alcohol. The association between cigarette or betel quid use and HNC risk was similar between the high and low educational groups. National policies and social interventions have led to the decline in the prevalence of cigarette and betel quid users in Taiwan. In contrast, due to the lack of adequate alcohol control policies, alcohol consumption in Taiwan has continued to rise. A higher impact of alcohol on HNC risk among lower SES individuals even with universal health care could be the result of insufficient alcohol control policies in Taiwan.

Occupational Class and Risk of Cardiovascular Disease Incidence in Japan: Nationwide, Multicenter, Hospital-Based Case-Control Study

Background

In contemporary Western settings, higher occupational class is associated with lower risk for cardiovascular disease (CVD) incidence, including coronary heart disease (CHD) and stroke. However, in non‐Western settings (including Japan), the occupational class gradient for cardiovascular disease risk has not been characterized.

Methods and Results

Using a nationwide, multicenter hospital inpatient data set (1984–2016) in Japan, we conducted a matched hospital case‐control study with ≈1.1 million study subjects. Based on a standard national classification, we coded patients according to their longest‐held occupational class (blue‐collar, service, professional, manager) within each industrial sector (blue‐collar, service, white‐collar). Using blue‐collar workers in blue‐collar industries as the referent group, odds ratios and 95% CIs were estimated by conditional logistic regression with multiple imputation, matched for sex, age, admission date, and admitting hospital. Smoking and drinking were additionally controlled. Higher occupational class (professionals and managers) was associated with excess risk for CHD. Even after controlling for smoking and drinking, the excess odds across all industries remained significantly associated with CHD, being most pronounced among managers employed in service industries (odds ratio, 1.19; 95% CI, 1.08–1.31). On the other hand, the excess CHD risk in higher occupational class was offset by their lower risk for stroke (eg, odds ratio for professionals in blue‐collar industries, 0.77; 95% CI, 0.70–0.85).

Conclusions

The occupational “gradient” in cardiovascular disease (with lower risk observed in higher status occupations) may not be a universal phenomenon. In contemporary Japanese society, managers and professionals may experience higher risk for CHD.

Cancer risk in road transportation workers: a national representative cohort study with 600,000 person-years of follow-up

We analysed cancer risk in road transportation workers (RTWs) exposed to traffic air pollution and motor vehicle engine exhaust using the Korean National Health Insurance Service database. RTWs were defined as individuals in the transportation workers group doing road transportation. First admission history of cancer within a 3-year wash-out period was defined as an incident case. The crude incidence, standardised incidence ratio (SIR), and 95% confidence interval (CI) of all cancer risk of RTWs were compared with those of government employees or the whole working population. In total, 3,074 cancer cases were found among RTWs. The respective SIRs and 95% CIs for cancers in RTWs compared with those in the whole population were as follows: liver and intrahepatic bile duct cancers, 1.15 and 1.04-1.27; other digestive organ cancers, 1.28 and 1.04-1.57; trachea, bronchus, and lung cancers, 1.28 and 1.15-1.43; and bladder cancer, 1.26 and 1.03-1.52, respectively. The corresponding SIRs and 95% CIs were also higher in RTWs than in government employees. RTWs have a high risk of developing cancer, including cancer in the liver, intrahepatic bile ducts, other digestive organs, trachea, bronchus, lung, and bladder. Our results can assist in establishing prevention strategies for various cancers in RTWs.

Sex-specific risks and trends in lung cancer mortality across occupations and economic activities in Switzerland (1990-2014)

OBJECTIVES

To assess lung cancer mortality across occupations and economic activities/industries in Switzerland using three statistical estimates.

METHODS

All Swiss residents aged 18-65 during the 1990 or 2000 censuses were followed through 2014 to ascertain information on date and cause of death. For every occupation and economic activity/industry, causal mortality ratios (CMR) and standardised mortality ratios (SMR) were computed using national cause-specific mortality rates. We also calculated relative SMR (rSMR) and conducted analyses stratified by socioeconomic variables, job skill level and calendar periods.

RESULTS

The study sample comprised 5 834 618 participants (111 162 348 person-years). SMR and CMR led to similar results, while rSMR were generally higher. We found 18 occupations in men, 10 occupations in women and 3 industries in each sex with an excess of lung cancer mortality. Among men, rubber and plastic products machine operators, and workers in mining and quarrying, and construction industries were at high risk. Among women, motor vehicle drivers and workers in trade, repair of motor vehicles and of domestic articles and manufacture of goods industries showed the highest risks. In both sexes, hotel and restaurant workers presented an excess of lung cancer mortality.

CONCLUSION

Most of the activities and occupations in which we observed excess lung cancer mortality have previously been observed to involve occupational exposure to lung carcinogens. These findings suggest that the number of occupational lung cancer is likely underestimated by the official Swiss statistics. Further research should address this question and the exposure-effect relationships in the most at-risk occupational groups.

Cancer Incidence by Occupation in Korea: Longitudinal Analysis of a Nationwide Cohort

Background

We performed this study to investigate the inequalities in site-specific cancer incidences among workers across different occupations in Korea.

Methods

Subjects included members of the national employment insurance. Incident cancers among 8,744,603 workers were followed from 1995 to 2007. Occupational groups were classified according to the Korean Standard Occupational Classification. Age-standardized incidence rate ratios were calculated.

Results

We found that men in service/sales and blue-collar occupations had elevated rates of esophageal, liver, laryngeal, and lung cancer. Among women, service/sales workers had elevated incidences of cervical cancer. Male prostate cancer, female breast, corpus uteri, and ovarian cancers, as well as male and female colorectal, kidney, and thyroid cancer showed lower incidences among workers in lower socioeconomic occupations.

Conclusions

Substantial differences in cancer incidences were found depending on occupation reflecting socioeconomic position, in the Korean working population. Cancer prevention policy should focus on addressing these socioeconomic inequalities.

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

Background and aims

In Western countries, sex differences in renal cell carcinoma (RCC) histology and survival have been previously described: compared with men, clear cell subtype is more common but overall prognosis is better among women. The goal of the present study was to examine sex differences in RCC histology and survival in Japan, using a large-scale population-based data set.

Methods

With the use of a population-based cancer registry in Japan (2004-2016), patients with primary RCC were followed for 5 years (median follow-up time 2.1 years). We distinguished histological subtypes of clear cell, papillary, and chromophobe from "others" subtype. Sex-specific prevalence ratio (PR) for each histological subtype was estimated by Poisson regression with robust variance, adjusted for age and year of diagnosis. Sex-specific survival rates were estimated by Cox proportional hazard regression, adjusted for age, year of diagnosis, histological subtypes, and other prognostic variables, with multiple imputation.

Results

The prevalence of clear cell and "others" subtypes was similar between men and women among all the 5265 study subjects during the 12 years of study (clear cell, male 88.6% vs female 87.1%; "others", male 5.3% vs female 5.3%). However, papillary subtype was less common among women than men (male 4.6% vs female 2.8%; PR = 0.63; 95% CI, 0.45-0.88), while chromophobe subtype was more common among women (male 1.6% vs female 4.8%; PR = 3.18; 95% CI, 2.26-4.47). Although "others" subtype (but not papillary/chromophobe subtypes) independently predicted prognosis (HR = 1.74; 95% CI, 1.32-2.30), no sex differences were observed in RCC survival.

Conclusion

We did not observe a statistically significant difference in the prevalence of clear cell subtype between men and women in Japan, which differs from the pattern previously described in Western countries. Sex differences in RCC histology may not affect RCC survival in this population.

Occupational disparities in bladder cancer survival: A population-based cancer registry study in Japan

Background

Little is known about occupational disparities in bladder cancer survival.

Methods

Using data from a population‐based cancer registry (1970‐2016), we identified 3593 patients with incident bladder cancer diagnosed during 1970‐2011 who completed occupational information. The patients were followed for 5 years (median follow‐up time 5.0 years). Their longest‐held occupations at incident bladder cancer diagnosis were classified according to a national standardized classification. Hazard ratios (HRs) and 95% confidence intervals (CIs) for overall death were estimated by Cox proportional hazard model, adjusted for age, sex, and year of diagnosis. Clerical workers served as the reference group.

Results

Overall prognosis was fair in this population (5‐year overall survival, 61.9%). Compared with patients in clerical jobs, survival was poorer for those in professional and managerial jobs (mortality HR 1.36; 95% CI 1.09‐1.69), sales and service jobs (HR 1.25, 95% CI 1.01‐1.56), construction jobs (HR 1.83, 95% CI 1.40‐2.38), and manufacturing jobs (HR 1.32, 95% CI 1.05‐1.66), as well as those not actively employed (HR 1.27, 95% CI 1.02‐1.58). A similar pattern was observed in the subgroup analyses restricted to male patients as well as additional analyses adjusted for potential prognostic variables (eg, stage) with multiple imputation.

Conclusion

We documented occupational disparities in bladder cancer survival in Japan. However, the pattern of disparity did not favor highest occupational groups.

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

BACKGROUND

Even light to moderate alcohol consumption has been shown to increase cancer incidence. However, this association has not been well characterized in Japan.

METHODS

Based on a nationwide, hospital-based data set (2005-2016), a multicenter case-control study was conducted (63,232 cancer cases and 63,232 controls matched for sex, age, admission date, and admitting hospital). The total amount of lifetime alcohol consumption (drink-years) was recalled for each patient by multiplication of the daily amount of standardized alcohol use (drinks per day) and the duration of drinking (years). Odds ratios (ORs) were estimated for overall and specific cancer sites via conditional logistic regression with restricted cubic splines, with adjustments made for smoking, occupational class, and comorbidities. Lifetime abstainers served as the reference group.

RESULTS

Spline curves showed a dose-response association with overall cancer risk: the minimum risk was at 0 drink-years, and the OR at 10 drink-years was 1.05 (95% confidence interval [CI], 1.04-1.06). In comparison with lifetime abstainers, the OR for >0 to 20 drink-years was 1.06 (95% CI, 1.01-1.11). Those who drank 2 drinks or fewer per day had elevated odds for overall cancer risk across all duration-of-drinking categories. The same patterns were observed at light to moderate levels of drinking for most gastrointestinal/aerodigestive cancers as well as breast and prostate cancers. Analyses stratified by sex, different drinking/smoking behaviors, and occupational class mostly showed the same patterns for overall cancer incidence associated with light to moderate levels of drinking.

CONCLUSIONS

In Japan, even light to moderate alcohol consumption appears to be associated with elevated cancer risks.

Occupational Differences in C-Reactive Protein Among Working-Age Adults in South Korea

OBJECTIVE

To examine the association between occupational class and high-sensitivity C-reactive protein (hsCRP) in Korean workers.

METHODS

We used a nationally representative sample of Koreans (n = 2591) aged 19 to 65 years from the 2015 Korea National Health and Nutrition Examination Survey. The concentration of hsCRP (mg/L) was assessed by a high sensitivity immunoturbidimetric assay. Current occupation was categorized as: white-collar (managers/professionals), pink-collar (clerks/service/sales), blue-collar (craft/equipment/machine-assembling, agricultural/forestry/fishery, and elementary-level labor), or unemployed. Cross-sectional linear regression models adjusted for sociodemographic/work-related/health conditions and behaviors.

RESULTS

Compared with blue-collar workers, white-collar workers showed significantly higher levels of hsCRP (β = 0.16, 95% CI: 0.02, 0.30) after adjusting for all covariates, whereby the pattern was more pronounced among professionals. However, the association was not significant for unemployed and pink-collar workers.

CONCLUSIONS

Findings suggest that Korean white-collar workers, particularly professionals, have elevated levels of inflammation.

Risk of cancer and longest-held occupations in Japanese workers: A multicenter hospital-based case-control study

Objectives

Little is known about the risk of developing various cancers according to occupation and occupational physical activity.

Methods

Using nationwide clinical inpatient data (1984‐2017) in Japan, we undertook a multicentered, matched case‐control study with regard to the risk of developing various cancers according to occupation and using patients admitted with fractures as controls. Using standardized national occupation and industrial classifications, we first identified the longest‐held job for each patient. Using sales workers as the reference group, odds ratios (ORs) and 95% confidence intervals (CIs) were estimated by conditional logistic regression, adjusted for age, admission period, and the admitting hospital, with smoking, alcohol consumption, and lifestyle diseases as covariates. The risk of high and low occupational physical activity was also estimated.

Results

Across all occupations, a reduced risk for all common cancers among males was observed among those occupations associated with high physical activities, such as agriculture. People in these occupations tended to show a lower risk for most cancers, including, for example, prostate cancer (OR 0.58, 95% CI 0.45‐0.75) and lung cancer (OR 0.63, 95% CI 0.51‐0.76). For females, the breast cancer risk was low in women engaged in agriculture (OR 0.58, 95% CI 0.45‐0.75) and in those occupations with high levels of occupational physical activity (OR 0.58, 95% CI 0.52‐0.66).

Conclusions

This study revealed differences in cancer risk among diverse occupations in Japan. Specifically, those occupations associated with high levels of physical activity may be associated with a decreased risk of cancer.

Occupational class differences in pancreatic cancer survival: A population-based cancer registry-based study in Japan

Background

Little is known about occupational class differences in pancreatic cancer survival.

Methods

Using a population‐based cancer registry in Japan, 3 578 patients with incident pancreatic cancer (1970‐2011) were followed up for 5 years (median follow‐up time 0.42 years). We classified patients into four occupational classes based on their longest‐held jobs: white‐collar (professional and managers), service, blue‐collar, and those not actively employed. Using white‐collar class as the reference group, hazard ratios (HRs) and 95% confidence intervals (CIs) for overall death were estimated by Cox proportional hazard model. Covariates included age, sex, and year of diagnosis. Prognostic variables (pathology, stage, and treatment) and smoking behaviors were additionally adjusted as possible mediating factors.

Results

Overall survival was poor in this population (median, 0.50 and 0.33 years in white‐collar and service classes, respectively). Compared with white‐collar patients, survival was significantly poorer across all occupational classes, most pronounced in the service worker group: mortality HRs ranged from 1.11 (95% CI 1.00‐1.24) in blue‐collar workers to 1.24 (95% CI 1.12‐1.37) in service workers. Even after controlling for potential mediating factors, service workers showed worse survival.

Conclusion

We documented occupational class disparities in pancreatic cancer survival in Japan. Even in the setting of lethal prognostic cancer with universal health coverage, high‐occupational class groups may enjoy a health advantage.

Occupational class and male cancer incidence: Nationwide, multicenter, hospital-based case-control study in Japan

Little is known about socioeconomic inequalities in male cancer incidence in nonwestern settings. Using the nationwide clinical and occupational inpatient data (1984‐2016) in Japan, we performed a multicentered, matched case–control study with 214 123 male cancer cases and 1 026 247 inpatient controls. Based on the standardized national classifications, we grouped patients’ longest‐held occupational class (blue‐collar, service, professional, manager), cross‐classified by industrial cluster (blue‐collar, service, white‐collar). Using blue‐collar workers in blue‐collar industries as the referent group, odds ratios (ORs) and 95% confidence intervals (CIs) were estimated by conditional logistic regression with multiple imputation, matched for age, admission date, and admitting hospital. Smoking and alcohol consumption were additionally adjusted. Across all industries, a reduced risk with higher occupational class (professionals and managers) was observed for stomach and lung cancer. Even after controlling for smoking and alcohol consumption, the reduced odds persisted: OR of managers in white‐collar industries was 0.80 (95% CI 0.72‐0.90) for stomach cancer, and OR of managers in white‐collar industries was 0.66 (95% CI 0.55‐0.79) for lung cancer. In white‐collar industries, higher occupational class men tended to have lower a reduced risk for most common types of cancer, with the exception of professionals who showed an excess risk for prostate cancer. We documented socioeconomic inequalities in male cancer incidence in Japan, which could not be explained by smoking and alcohol consumption.