occupational class groups as a risk factor for gastrointestinal cancer: a case-control study

background: cancer has a high mortality rate in both developing and developed countries. 11%–15% of cancers are attributable to occupational risk factors. objective: to determine if specific occupational classes, based on the international standard for classification of occupations 2008 (isco-08), are risk factors for gastrointestinal (gi) cancer. methods: in this case-control study, 834 cancer patients were interviewed by a single physician. cases included patients with gi cancer. age-matched controls were selected from non- gi cancer patients. each year of working, up until 5 years before the diagnosis, was questioned and categorized by the isco classification. results: 243 gi cancer cases and 243 non-gi cancer patients (486 in total) were studied. working in isco class 8 (plant and machine operators, and assemblers) was significantly associated with higher risk of gi cancer (or 1.63, 95% ci 1.05 to 2.52). working in isco class 6 (skilled agricultural, forestry and fishery workers) and 9 (elementary occupations) were also associated with higher incidence of gi cancers. conclusion: working in isco classes of 8, 6, and 9, which are usually associated with low socio-economic status, can be considered a risk factor for gi cancers.