MONDAY, May 19 (HealthDay News) -- Firefighters may be at increased risk for bladder cancer and should be considered for routine annual screening, say University of California, San Francisco, researchers.

The team tested 1,286 active and retired San Francisco firefighters, whose mean age was 45, and found that 93 tested positive for blood in the urine (hematuria), and six tested positive for nuclear matrix protein 22 (NMP-22), which is released by bladder cancer cells. Those 99 patients were referred for upper tract imaging, cystoscopy and urine cytology.

Of those 99 patients, one tested positive for both NMP-22 and hematuria. Two of the patients -- both retired firefighters -- were diagnosed with bladder cancer.

The age- and sex-adjusted incidence for bladder cancer among the firefighters was 36 per 100,000, which is higher than that of the general population. The findings suggest that retired firefighters may be at high risk for bladder cancer, the researchers said.

They were expected to present their findings at a press conference Monday at the annual scientific meeting of the American Urological Association, in Orlando, Fla.

It has long been known that prolonged exposure to certain environmental pollutants and chemicals increases the risk of bladder cancer, according to background information in a news release about the study.

As the body absorbs cancer-causing chemicals, they're transferred to the blood, filtered out by the kidneys, and expelled from the body in urine. High concentrations of chemicals in urine can damage the endothelial lining of the bladder and increase the risk of cancer.

Because firefighters are regularly exposed to smoke and chemical fumes, they may be at increased risk for bladder cancer. Currently, there are no guidelines for regular bladder cancer screening.

More information

The American Cancer Society has more about bladder cancer.