Occupational cancer in Britain. Female cancers: breast, cervix and ovary

How the Intensity of Night Shift Work Affects Breast Cancer Risk

Background-In 2019, the IARC concluded that "night shift work is probably carcinogenic to humans (Group 2A), based on limited evidence from human epidemiological studies and sufficient evidence of cancer and strong mechanistic evidence in experimental Animals." The negative health consequences of night shift work may depend on how the night shifts are scheduled. The aim of this study was to investigate how the characteristics of night work affect the risk of developing breast cancer. Methods-A case-control study was conducted in 2015-2019 in the Lodz region. The case group included 494 women with breast cancer, while the control group included 515 healthy women. Results-Night work was found to be the third most important factor regarding breast cancer after a high BMI and a short or no breastfeeding period and before factors such as early menstruation, late menopause, no pregnancy, and smoking. The harmful effects of night work were influenced by its intensity, frequency, rotation, and the number of night shift years worked. Night work increases the breast cancer risk by 2.34 times, and high-intensity night work increases the breast cancer risk by 2.66 times. Conclusions-Appropriate ergonomic recommendations for night shift work for employers should be considered.

Cervical cancer related to occupational risk factors: review

Background

Occupational risk factors are associated with many types of neoplasms including cervical cancer.

Objective

To review the specialized literature for evidence on the relationship between cervical cancer and exposure to occupational hazards.

Methods

Literature search in electronic databases using keywords cervical cancer and occupational risk.

Results

Workers occupationally exposed to tobacco, fungi or bacteria, metalworking fluids and tetrachloroethylene used in dry cleaning and for metal degreasing exhibited higher susceptibility to cervical cancer.

Conclusion

Few studies sought to investigate relationships between cervical cancer and occupational hazards, which hinders the attempts at establishing a causal link.

Education, income and occupation and their influence on the uptake of cervical cancer prevention strategies: A systematic review

AIMS

To report a systematic review of the literature exploring how education, income and occupation influence the uptake of cervical screening and HPV vaccination among eligible women in developed countries, including the United Kingdom, United States, Spain, Germany and Norway.

BACKGROUND

Cervical cancer remains a highly prevalent disease despite it being largely preventable through cervical screening and HPV vaccination. Incidence and mortality of cervical cancer are unequally distributed among socioeconomic groups, warranting research into how individual socioeconomic factors contribute to this unbalanced uptake of prevention strategies.

DESIGN

Systematic review and narrative synthesis.

METHODS

The PRISMA guidelines (PLoS Medicine, 6, 2009, e1000097) guided the selection of papers. MEDLINE, CINHAL, PsychINFO, Science Citation Index and HMIC were searched. Ten articles were suitable. Key findings were then extracted, and a narrative synthesis was completed, using suitable guidance and the AXIS tool.

RESULTS

Obtaining high school or college education is associated with uptake of both cervical screening and HPV vaccination. Total household income and income in respect of the countries' poverty line was measured less frequently than education, but associated with screening and vaccination in some studies. Occupation was infrequently measured in comparison to education and income, limiting conclusions of its association to uptake.

CONCLUSION

Education and income have an association with uptake of cervical screening and HPV vaccination among women. However, evidence is insufficient to affirm a relationship between occupation and uptake of screening and vaccination. Further research would be advised to strengthen these findings.

RELEVANCE TO CLINICAL PRACTICE

Interventions to promote cervical cancer prevention strategies should be targeted at women and girls with lower education levels and lower income. However, differences are displayed in the relationships between the individual socioeconomic factors and uptake of preventative strategies between countries and populations and so they should be considered separately. Nurses play a considerable role in people's perceptions and experiences of cervical screening and HPV vaccination. The review findings offer new insight that can inform future policy and nursing practice on targeting interventions to promote uptake among women who are underusing cervical cancer prevention programmes.

The impact of night shift work on breast cancer: Results from the Burden of Occupational Cancer in Canada Study

BACKGROUND

We estimated the proportion and number of female breast cancer cases in Canada attributable to night shift work, a probable cause of breast cancer.

METHODS

Levin's equation was used to calculate population attributable fractions (PAFs) among Canadian women who ever worked night/rotating shifts from 1961 to 2000, accounting for labor turnover and survival to the year 2011. The calculated PAFs were applied to 2011 Canadian breast cancer incidence statistics to obtain the number of attributable cases.

RESULTS

Approximately 1.5 million women ever worked night/rotating shifts during 1961-2000 and survived to 2011. The PAFs ranged from 2.0% (95% confidence interval [CI]: 1.4-6.2) to 5.2% (95% CI: 3.7-13.6), and 470 to 1200 incident breast cancer cases in 2011 were likely due to shift work, of which 38% would have been diagnosed among women in health-related occupations.

CONCLUSIONS

More research is needed to increase the certainty of this association, but current evidence supports workplace-based prevention.

Night shift work and risk of breast cancer in women: the Generations Study cohort

Background

It is plausible that night shift work could affect breast cancer risk, possibly by melatonin suppression or circadian clock disruption, but epidemiological evidence is inconclusive.

Methods

Using serial questionnaires from the Generations Study cohort, we estimated hazard ratios (HR) and 95% confidence intervals (95%CI) for breast cancer in relation to being a night shift worker within the last 10 years, adjusted for potential confounders.

Results

Among 102,869 women recruited in 2003–2014, median follow-up 9.5 years, 2059 developed invasive breast cancer. The HR in relation to night shift work was 1.00 (95%CI: 0.86–1.15). There was a significant trend with average hours of night work per week (P = 0.035), but no significantly raised risks for hours worked per night, nights worked per week, average hours worked per week, cumulative years of employment, cumulative hours, time since cessation, type of occupation, age starting night shift work, or age starting in relation to first pregnancy.

Conclusions

The lack of overall association, and no association with all but one measure of dose, duration, and intensity in our data, does not support an increased risk of breast cancer from night shift work in women.

Occupational exposure to endocrine disrupting substances and the risk of breast Cancer: the Singapore Chinese health study

Background

Evidence from basic research links exposure to endocrine disrupting chemicals (EDCs) with a higher risk for breast cancer. However, there is less evidence from observational epidemiological research and the results are equivocal. Therefore, we examined the association between occupational exposure to substances where exposure to EDCs is likely and the risk of breast cancer.

Methods

A prospective study consisting of a population-based cohort of 33,458 Singaporean Chinese women aged 45–74 years enrolled in the Singapore Chinese Health Study (SCHS) from 1993 to 98 and followed through 2014. Subjects’ self-reported occupational exposure and duration to industries, job titles, and substance types were garnered at baseline, and cases of incident breast cancer (N = 988) were determined by linkage with the Singapore Cancer Registry. Hazard ratios (HR) and 95% confidence intervals (CI) were estimated for exposure to substances, job titles, and industries.

Results

There was no association between cumulative exposure to substances via occupation where EDC exposure is likely and risk of breast cancer. These results were consistent for hypothesized high (HR 0.94, 95% CI: 0.66–1.35), medium (HR 1.03 95% CI: 0.77–1.38) and low (HR 0.74, 95% CI 0.48–1.13) combined substance exposure groups when compared with those who were not exposed via occupation. Similar null associations were observed when examining job titles and industry categories.

Conclusions

There was no association between EDC related occupational exposures and breast cancer risk in working women of the Singaporean Chinese Health Study. Future studies that employ rigorous methods with regard to exposure assessment of EDCs are needed.

Electronic supplementary material

The online version of this article (10.1186/s12889-018-5862-2) contains supplementary material, which is available to authorized users.

State of the evidence 2017: an update on the connection between breast cancer and the environment

BACKGROUND

In this review, we examine the continually expanding and increasingly compelling data linking radiation and various chemicals in our environment to the current high incidence of breast cancer. Singly and in combination, these toxicants may have contributed significantly to the increasing rates of breast cancer observed over the past several decades. Exposures early in development from gestation through adolescence and early adulthood are particularly of concern as they re-shape the program of genetic, epigenetic and physiological processes in the developing mammary system, leading to an increased risk for developing breast cancer. In the 8 years since we last published a comprehensive review of the relevant literature, hundreds of new papers have appeared supporting this link, and in this update, the evidence on this topic is more extensive and of better quality than that previously available.

CONCLUSION

Increasing evidence from epidemiological studies, as well as a better understanding of mechanisms linking toxicants with development of breast cancer, all reinforce the conclusion that exposures to these substances - many of which are found in common, everyday products and byproducts - may lead to increased risk of developing breast cancer. Moving forward, attention to methodological limitations, especially in relevant epidemiological and animal models, will need to be addressed to allow clearer and more direct connections to be evaluated.

Occupational exposure and risk of breast cancer

Breast cancer is a multifactorial disease and the most commonly diagnosed cancer in women. Traditional risk factors for breast cancer include reproductive status, genetic mutations, family history and lifestyle. However, increasing evidence has identified an association between breast cancer and occupational factors, including environmental stimuli. Epidemiological and experimental studies demonstrated that ionizing and non-ionizing radiation exposure, night-shift work, pesticides, polycyclic aromatic hydrocarbons and metals are defined environmental factors for breast cancer, particularly at young ages. However, the mechanisms by which occupational factors can promote breast cancer initiation and progression remains to be elucidated. Furthermore, the evaluation of occupational factors for breast cancer, particularly in the workplace, also remains to be explained. The present review summarizes the occupational risk factors and the associated mechanisms involved in breast cancer development, in order to highlight new environmental exposures that could be correlated to breast cancer and to provide new insights for breast cancer prevention in the occupational settings. Furthermore, this review suggests that there is a requirement to include, through multidisciplinary approaches, different occupational exposure risks among those associated with breast cancer development. Finally, the design of new epigenetic biomarkers may be useful to identify the workers that are more susceptible to develop breast cancer.

Association of breast cancer with sleep pattern--a pilot case control study in a regional cancer centre in South Asia

The rising trend of breast cancer both in developed and developing countries is a real threat challenging all efforts to screening, prevention and treatment aspects to reduce its impact. In spite of modern preventive strategies, the upward trend of breast cancer has become a matter of great concern in both developed and developing countries. Chittaranjan National Cancer Institute is a premier regional cancer institute in eastern region of India catering to a large number of cancer patients every year. A pilot case control study of fifty breast cancer patients and 100 matched controls was conducted during 2013 to evaluate the effects of habitual factors like working in night shift, not having adequate sleep, and not sleeping in total darkness on breast cancer of women. The study revealed that not sleeping in total darkness was associated with higher odds of outcome of breast cancer of women. This positive correlation can play a vital role in formulation of preventive strategies through life style modification.

Mortality among 24,865 workers exposed to polychlorinated biphenyls (PCBs) in three electrical capacitor manufacturing plants: a ten-year update

The objective of this analysis was to evaluate mortality among a cohort of 24,865 capacitor-manufacturing workers exposed to polychlorinated biphenyls (PCBs) at plants in Indiana, Massachusetts, and New York and followed for mortality through 2008. Cumulative PCB exposure was estimated using plant-specific job-exposure matrices. External comparisons to US and state-specific populations used standardized mortality ratios, adjusted for gender, race, age and calendar year. Among long-term workers employed 3 months or longer, within-cohort comparisons used standardized rate ratios and multivariable Poisson regression modeling. Through 2008, more than one million person-years at risk and 8749 deaths were accrued. Among long-term employees, all-cause and all-cancer mortality were not elevated; of the a priori outcomes assessed only melanoma mortality was elevated. Mortality was elevated for some outcomes of a priori interest among subgroups of long-term workers: all cancer, intestinal cancer and amyotrophic lateral sclerosis (women); melanoma (men); melanoma and brain and nervous system cancer (Indiana plant); and melanoma and multiple myeloma (New York plant). Standardized rates of stomach and uterine cancer and multiple myeloma mortality increased with estimated cumulative PCB exposure. Poisson regression modeling showed significant associations with estimated cumulative PCB exposure for prostate and stomach cancer mortality. For other outcomes of a priori interest--rectal, liver, ovarian, breast, and thyroid cancer, non-Hodgkin lymphoma, Alzheimer disease, and Parkinson disease--neither elevated mortality nor positive associations with PCB exposure were observed. Associations between estimated cumulative PCB exposure and stomach, uterine, and prostate cancer and myeloma mortality confirmed our previous positive findings.