Do firefighters get prostate cancer because of their work?

When it comes to lung cancer, we know of more than 30 substances that are carcinogenic. But when researchers began investigating why there is a higher incidence of prostate cancer among firefighters, they had little to go on.

Previous research from the Cancer Registry of Norway has found that firefighters develop prostate cancer more frequently than the general population. However, the cause has remained unclear.

(Photo: Marc Kleen / Unsplash)

Cecilie Bakken Høstmark Communications Adviser

Presented by: University of Oslo

Published 21 March 2025 - 00:01

Prostate cancer is the most common form of cancer among men. Up until now, however, no substance has been classified as a definite carcinogenic agent for this type of cancer by the World Health Organisation’s cancer research agency IARC.

IARC defines an agent as substances, microorganisms, exposure situations, or occupations that can cause cancer.

When it comes to lung cancer, which is the second most common type of cancer among men, there are over 30 different agents classified as carcinogenic by IARC, including smoking and asbestos. For bladder cancer, there are 17, and for breast cancer, 5.

"But there are no known carcinogens for prostate cancer. It's surprising that we know so little about which substances are risk factors for this common type of cancer," says Niki Marjerrison.

She is a researcher at the University of Oslo's Institute of Basic Medical Sciences.

Researcher Niki Marjerrison compared the incidence of prostate cancer among those who had been most involved with firefighting with those who had been the least involved.

Is the amount of smoke and gases that firefighters inhale partly to blame?

Previous research from the Cancer Registry of Norway has found that firefighters are diagnosed with prostate cancer more often than the general population. However, the reasons for this have been unclear. Marjerrison therefore wanted to examine how factors such as smoke and gases at work affect the risk of developing prostate cancer.

Among the 4,251 firefighters in the new study, 268 were diagnosed with prostate cancer.

The researchers then looked at how long the firefighters had been in the profession and whether they had held positions that involved other tasks such as administration and fire prevention.

They also estimated how many fires the firefighters had helped put out. The aim was to find out whether exposure to smoke, various gases, chemicals, and other substances often present at fire sites affected the risk of getting prostate cancer.

"When we compared the incidence of prostate cancer among those who had been most involved with firefighting with those who had been the least involved, we found little evidence of a connection between firefighting and the risk of getting prostate cancer," says Marjerrison.

PSA tests may have affected the incidence of prostate cancer

According to Marjerrison, there are many factors that complicate studies on how environmental and occupational factors may influence the risk of prostate cancer.

One of these factors was examined more thoroughly by the researchers. They point out that something significant happened in the 1990s when PSA tests came into use.

This test measures the amount of a specific protein in the blood, which typically increases when there is cancer of the prostate gland, but can also increase due to benign prostate conditions.

"The use of PSA tests has meant that more cases of prostate cancer have been discovered than would otherwise have been the case. The PSA test is highly sensitive, which can be an advantage, but also results in positive test results at an early stage of conditions that would not cause problems in the future or require further treatment," explains Marjerrison.

This sensitive test may therefore have been one of the reasons for the increased number of registered cases of prostate cancer among firefighters.

To address this issue of PSA testing, the researchers isolated and studied the aggressive cases of prostate cancer separately, as these were considered less likely to have been detected through random testing.

"In total, 61 cases were classified as aggressive. This low number provides too weak statistical evidence to be able to point to a definite connection," she says.

The researchers found that firefighters were younger and more often had cancers with a better prognosis – meaning they were less aggressive – compared to the general population.

This suggests more frequent PSA testing and increased diagnosis. However, information on PSA testing was not available for each individual firefighter, so it could not be directly accounted for in the analyses.

Upcoming report on cancer among firefighters

Another challenge for the researchers has been that firefighters work in a wide range of emergency situations. This makes it difficult to precisely determine and measure what factors firefighters are actually exposed to during a fire, says Marjerrison.

The research team therefore developed so-called indicators for the substances the firefighters were exposed to, but they still found no evidence that higher values of these indicators increased the risk of prostate cancer.

Reference:

Marjerrison et al. Occupational exposures of firefighting and prostate cancer risk in the Norwegian Fire Departments Cohort, Scandinavian Journal of Work, Environment & Health, vol. 51, 2025. DOI: 10.5271/sjweh.4202

About the research

The research into cancer among firefighters in Norway was initiated about ten years ago by the Cancer Registry of Norway. Marjerrison and other researchers in the EpiStat group at the University of Oslo and the Cancer Registry Norway have compiled a report that summarises the studies that have been carried out over the past ten years.

The study was funded by the Dam Foundation, the Norwegian Cancer Society, Firefighters against Cancer, the Norwegian Union of Municipal and General Employees, the Norwegian Union of Maritime Engineers, and the Firefighters’ Union in Delta.