Application of two job indices for general occupational demands in a pooled analysis of case-control studies on lung cancer

OBJECTIVES: We investigated general job demands as a risk factor for lung cancer as well as their role in the association between occupational prestige and lung cancer.

METHODS: In 13 case-control studies on lung cancer, as part of the international SYNERGY project, we applied indices for physical (PHI) and psychosocial (PSI) job demands - each with four categories (high to low). We estimated odds ratios (OR) and 95% confidence intervals (CI) for lung cancer by unconditional logistic regression, separately for men and women and adjusted for study centre, age, smoking behavior, and former employment in occupations with potential exposure to carcinogens. Further, we investigated, whether higher risks among men with low occupational prestige (Treiman's Standard International Occupational Prestige Scale) were affected by adjustment for the job indices.

RESULTS: In 30 355 men and 7371 women, we found increased risks (OR) for lung cancer with high relative to low job demands in both men [PHI 1.74 (95% CI 1.56-1.93), PSI 1.33 (95% CI 1.17-1.51)] and women [PHI 1.62 (95% CI 1.24-2.11), PSI 1.31 (95% CI 1.09-1.56)]. OR for lung cancer among men with low occupational prestige were slightly reduced when adjusting for PHI [low versus high prestige OR from 1.44 (95% CI 1.32-1.58) to 1.30 (95% CI 1.17-1.45)], but not PSI.

CONCLUSIONS: Higher physical job demands were associated with increased risks of lung cancer, while associations for higher psychosocial demands were less strong. In contrast to physical demands, psychosocial demands did not contribute to clarify the association of occupational prestige and lung cancer.