Prostate cancer is the most common cancer among men; however, little is known about its aetiology. Several studies have indicated that firefighters have an increased risk, but the results have not been consistent. Firefighters are exposed to many harmful substance in their work, some of which are carcinogenic. Two reviews with meta-analyses, including studies through 2003 and 2007, respectively, found that firefighters had approximately 30% elevated risk of prostate cancer. Our objective was to perform an updated review and meta-analyses of studies published after 2007.Methods
We performed a literature review of original articles of prostate cancer in firefighters, published between January 2008 and May 2017. For the meta-analysis, we selected relevant longitudinal studies and calculated summary risk ratios (sumRRs).Result
Six studies, published 2008–2016, with a total of 5097 prostate cancer cases, were selected for the analysis; four were cohort studies and two case-control. Eight risk estimates were included in the meta-analysis, seven incidence based, one mortality based. All showed weak to moderate positive associations between firefighting and prostate cancer, although some not statistically significant. Meta-analysis of five incidence based risk estimates from cohort studies, gave sumRR 1.20 (95% CI: 1.05 to 1.36). Results based on the two case-control incidence studies gave sumRR 1.24 (0.90–1.70). When all eight risk estimates were included in the meta-analysis, sumRR was 1.19 (1.08–1.32). Further analyses, however, showed significant heterogeneity between the studies.Discussion
The results showed that firefighters had approximately 20% increased risk of prostate cancer, somewhat lower than the previous two meta-analyses found. However, occupational title may be an inaccurate measure of carcinogenic exposures and thus lead to underestimation of the cancer risk. On the other hand, reasons other than a causal relationship, particularly surveillance bias, caused by regular health examinations among firefighters, cannot be excluded.