Lung Cancer Risk in Relation to Jobs Held in a Nationwide Case-Control Study in Iran

Abstract

Background: Globally, lung cancer is the most frequent occupational cancer, but the risk of lung cancer related to the occupations in Iran is not clear. We aimed to assess whether workers in various occupational groups would experience an increased lung cancer risk. Methods: We used the IROPICAN nationwide hospital-based case-control study including 658 incident lung cancer cases and 3477 controls. We assessed the risk of cancer in relation to ever working in major International Standard Classification of Occupations (ISCO-68) groups and specific jobs, while controlling for individual potential confounders including cigarette smoking and opium consumption. Results: We observed elevated odds ratio (OR) for lung cancer in male construction workers (OR=1.4; 95% confidence interval (CI), 1.0- 1.8), and petroleum industry workers (3.2; CI, 1.1- 9.8), and in female farmers (2.6; CI, 1.3- 5.3), and female bakers (5.5; CI, 1.0, 29.8). The positive trend has been observed for the duration of employment as a construction worker in men (p trend < 0.004), and farming in women (p trend < 0.5). Increase risk of squamous cell carcinoma (SCC) was associated with ever construction industry workers for males (1.9; CI, 1.2- 3.0), whilst both SCC and adenocarcinoma subtypes were associated with working as farmers for females (3.8; CI, 1.4- 9.9), even more pronounced for adenocarcinoma (4.3; CI, 1.1- 17.2). Conclusion: Although we did observe association between some occupations and lung cancer, we recommend developing an occupational exposure assessment tool specific for working conditions in Iran to allow the study of specific occupational agents. Keywords: Occupational cancer, Lung cancer, Exposure, Carcinogen, Iran