Scrotal carcinoma in Connecticut metalworkers: sequel to a study of sinonasal cancer.

An excess risk for sinonasal cancer among Connecticut metalworkers with potential exposure to cutting oils led to the hypothesis of a relationship between the same occupational category and squamous cell carcinoma of the scrotum. Cases of this latter tumor (n = 45) diagnosed in 1935-1973 were identified by the Connecticut Tumor Registry. For decedents, male controls from Connecticut death certificates were matched to decedent cases on age, year of birth, and availability of occupational information; for living subjects, male controls from records of the Connecticut Department of Motor Vehicles were matched on the above variables and town of residence. Death certificates and city directories provided occupational information. For the narrowly defined indicator of cutting oil exposure (toolmaker, setter, set-up man, hardener, polisher, automatic screw machine operator), the odds ratio for squamous cell carcinoma of the scrotum was 4.9, 95% confidence limits (CL): 1.8, 15.9. The broad indicator of cutting oil exposure (not otherwise specified) categories plus machinist and machine operator (not otherwise specified) had an odds ratio of 10.5, 95% CL: 4.0, 36.9 and explained 57% of the cancers. For this broad category, the risk persisted in the most recent time period of diagnosis, 1966-1973 (OR = 18.6). For this broad category, major biases could not be detected when the following additional covariables were taken into account individually where possible: source of occupation, nativity, town of residence, stage at diagnosis, and cause of death. City directory and death certificate information implied that at least 80% of cases in the high risk category worked in the Connecticut region before age 40.