Bladder cancer rates rising in most occupations exposed to carcinogens: Review

Rates 16.6 times higher for factory workers, 13.4 for hairdressers

NEW YORK (Reuters Health) — Bladder cancer rates are rising, especially among women, and occupational exposure to carcinogens may be responsible, according to a meta-analysis.

"Occupational bladder cancer is a current problem and not a historical issue," Dr. James W. F. Catto from the Medical School, University of Sheffield, Sheffield, England, told Reuters Health by email.

In the 1980s, an estimated 10 per cent of bladder cancers arose from occupational exposure. Workplace legislation should have reduced this rate, but whether this is the case remains to be seen, according to the researchers.

Dr. Catto's team investigated whether social and workplace legislative changes have altered the risk for bladder cancer through their systematic review and meta-analysis of 263 contemporary reports of occupational exposure and bladder carcinogenesis in 1,254 occupations.

Compared with the general population, bladder cancer incidence rates were 16.6 times higher for factory workers, 13.4 times higher for hairdressers, and 11.8 times higher for aircraft/ship's officers. Bladder cancer mortality rates were 27.1 times higher for chemical workers and 8.3 times higher for dye workers.

There was a steady decline in standardized incidence ratios (SIRs) between the 1960s and 1980s for both sexes, but the trend reversed in the 1980s and in the first decade of the 21st century the SIR increased to 1.13 for men and 1.27 for women.

SIRs were higher for women than for men, but standardized mortality ratios (SMRs) were higher for men than for women, according to the October 8 JAMA Oncology online report.

The incidence of bladder cancer increased in 42 of 61 (67 per cent) and decreased in 6 of 61 (10 per cent) occupational classes. The highest risks were for workers exposed to aromatic amines (tobacco, dye, and rubber workers; hairdressers; printers; and leather workers) and polycyclic aromatic hydrocarbons (PAHs) (chimney sweeps, nurses and waiters, aluminum workers, seamen, and oil/petroleum workers).

Agricultural sector workers had the lowest occupational bladder cancer risk.

The highest bladder cancer mortality rates occurred in workers exposed to heavy metals and PAHs and those exposed to aromatic amines.

Exposures included 44 agents with a reported role in urothelial carcinogenesis.

"While there have been reductions in occupational bladder cancer incidence and mortality, it appears that there may still be many occupations with an elevated incidence or mortality risk," the researchers concluded. "This persists despite improvements in workplace hygiene, although the profile of at-risk occupations has changed over time and may differ for bladder cancer incidence and mortality. Efforts to reduce the impact of bladder cancer on workers should be targeted to occupations at risk of mortality."

Dr. Catto recommended "education of staff regarding the symptoms of bladder cancer. We found evidence of an incidence-mortality disconnect. For example, there were occupations with high incidence and low mortality in educated (medical staff) or screened workers (chemical industry)."

He also recommended "education of staff/employers regarding workplace safety, such as knowledge of diesel fume harm, secondhand tobacco smoke inhalation, or the use of carcinogenic agents in other industries."

Dr. Harri Vainio from Kuwait University, Kuwait, and former director general of the Finnish Institute of Occupational Health, coauthored an invited commentary related to this report. He told Reuters Health by email, "The surprising thing was the notion that while enormous progress with occupational bladder cancer has been achieved in places (such as the drastic reduction of exposures to beta-naphthylamine in industrial use in some countries over the last 40 years), there continue to be pockets and fields where bladder cancer risk is still elevated. The risk increase in women is particularly noteworthy, although at least partly, it can be explained by increased exposure to tobacco smoke."

"Unfortunately, industrial hygiene knowledge and expertise are regularly available only in some high-income countries, and therefore the responsibility lies also heavily on the producer and employer side," Dr. Vainio said. "The manufactured products should be adequately labeled, the suspicious chemicals in dyestuffs and elsewhere should be listed, and warning labels given, when considered necessary."

"For the physicians, one should not forget that occupational bladder cancer exists," he said. "The risk increase may not reach the level where bladder cancer could be recognized as an occupational disease, but even under these circumstances, there would be a need to manage the population (worker-) level risk by acting on general occupational hygiene."

Dr. Vainio added, "Cancer of the bladder seems more of an increase among women than in men. Watch out doing the same mistakes that we have done with men - women should be protected from this additional disease outcome."

Yorkshire Cancer Research, the Astellas Educational Foundation, and the Wellcome Trust supported this research. The authors reported no disclosures.

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