Racial and occupational variations in cancer of the testis: San Francisco, 1956-65.

During 1956-65, white and nonwhite San Francisco male residents did not have equal risks of developing testicular cancer. The lower risk observed for nonwhites could not be attributed entirely to genetic factors, since among whites a risk gradient seemed to correlate directly with broad socioeconomic indices such as occupation and census tract of residence. Although incidence rates for testicular cancer have progressively increased in the United States and now parallel rates in Danish towns and rural areas, they are still lower than rates observed in Copenhagen, where a "technology" effect has been postulated. In this perspective, the San Francisco findings are compatible with a hypothesis that certain occupational groups may have become epidemiologic indicators of testicular carcinogens in a changing environment.