Occupational exposures and risk of gastric cancer in a population-based case-control study

Gastric cancer trends seem to follow improvements in the environment of blu e-collar workers, but the etiological role of occupational exposures in gas tric carcinogenesis is scantily investigated. The risk of gastric adenocarc inoma in 10 common occupational Industries, and particularly the long-term effects of asbestos, organic solvents, impregnating agents, insecticides, a nd herbicides, were evaluated in a population-based case-control study, inc luding data on most established risk factors. The study base included all i ndividuals of ages 40-79, born in Sweden and living in either of two areas (total population, 1.3 million) with differing gastric cancer incidences, f rom February 1989 through January 1995, We interviewed 567 cases classified to site (cardia/noncardia) and histological type, and 1165 population-base d controls, frequency-matched for age and sex. Metal workers had a 46% exce ss gastric cancer risk [adjusted odds ratio (OR), 1.46; 95% confidence inte rval (CI), 1.10-1.94], increasing to 1.65 (95% CI 1.17-2.32) for >10 years in the industry. The elevated risk after exposure to herbicides (OR, 1.56; 95% CI, 1.13-2.15) was attributable to phenoxyacetic acids (adjusted OR, 1. 70; 95% CI, 1.16-2.48), similarly across tumor subtypes, and not modified b y smoking, body mass index, or Helicobacter pylori. The absence of interact ion was demonstrated by the pure multiplicative effect found among those ex posed to both H. pylori and phenoxyacetic acids (OR, 3.42; 95% CI, 1.41-8.2 6). Organic solvents, insecticides. Impregnating agents, and asbestos were not associated with gastric cancer risk. Employment in the metal industry a nd exposure to phenoxyacetic acids were both positively and independently a ssociated with gastric cancer risk. The fractions of all gastric cancers at tributable to these job-related exposures were small but not negligible (7 and 5%, respectively) in the Swedish population.