Bladder cancer screening among primary aluminum production workers in Quebec

We evaluated a cytology screening program, offered by a large aluminum producer after the discovery of an excess of bladder cancer due to occupational exposure to coal-tar-pitch volatiles, in terms of early detection and survival, based on information in the public domain. From January 1970 through June 1986, 79 cases of bladder cancer were identified in this cohort of aluminum workers aged 65 years or younger. By the end of 1986, 36 had died, with bladder cancer as the primary cause of death for 53%. Cases diagnosed after the screening program was introduced in 1980 were compared with those diagnosed earlier. In cases diagnosed after 1980, the proportion identified at early stages was higher (77% v 67%) and survival seemed improved but the differences were not statistically significant. Although these results do not encourage an optimistic view of screening effectiveness in this population, the limits inherent in the present study make it impossible to draw any firm conclusion. Studies restricted to public domain information do not appear to have sufficient data to evaluate workplace screening programs.