Risk of cancer among firefighters: a quantitative review of selected malignancies.

Using the fixed-effect model, the author quantitatively estimated the risks of cancers of the colon, bladder, kidneys, and brain as well as non-Hodgkin's lymphoma and leukemia among firefighters. The risk of these six cancers was not markedly elevated when cohort mortality studies were considered. When all mortality studies were considered, however, there was a mild increase in risk for kidney cancer and non-Hodgkin's lymphoma, with a summary relative risk (sumRR) of 1.22 (95% confidence interval [CI] = 1.02-1.43) and 1.40 (95% CI = 1.20-1.60), respectively. A subcohort analysis based on duration of employment revealed that firefighters with 30 or more years of employment had a significantly increased mortality risk for colon cancer, sumRR of 1.51 (95% CI = 1.05-2.11); kidney cancer, sumRR of 6.25 (95% CI = 1.70-16.00); brain cancer, sumRR of 2.53 (95% CI = 1.27 7.07); and leukemia, sumRR of 2.87 (95% CI = 1.43-5.14). After firefighters had 40 or more years of employment, their risk of mortality was significantly increased for colon cancer, sumRR of 4.71 (95% CI = 2.03-9.27); kidney cancer, sumRR of 36.12 (95% CI = 4.03-120.42); and bladder cancer, sumRR of 5.7 (95% CI = 1.56-14.63). The risk for non-Hodgkin's lymphoma was elevated but not significantly so among firefighters with 20 or more years of employment, with sumRR of 1.72 (95% CI = 0.90-3.31). Kidney cancer risk was significantly elevated as early as the second decade of employment.