Objectives The cancer incidence of population can be influenced by environmental and social factors including occupational factor. This study was performed to explore the cancer incidence in various occupations of Korean workers by following a large database.

Methods We built a cohort with workers who have entered the Employment Insurance during 1995–2000. The information of cancer incidence for the cohort was obtained by matching with database during 1995–2007 of the Korea Central Cancer Registry. Subjects eligible for analysis were 8,762,340 workers, and they were classified into nine subcohorts according to the Korean Standard Occupational Classification. Age-standardised cancer incidence rates (ASR) of each occupational group were calculated.

Results There were 245,125 cancer cases during 1995–2007. The ASR for all cancer was 380.5 per 100,000 in male and 357.6 per 100,000 in female. Among male workers, the highest ASR showed in technicians and associate professionals (404.5 per 100,000) and clerks (404.8 per 100,000). Among female workers, professionals (539.5) showed highest ASR. Agricultural, Forestry and Fishery Workers showed the lowest ASR (M: 319.4, F: 194.0). However, ASRs for lung cancer were highest in Elementary occupations (49.8) and Technicians and associate professionals (45.8). In case of breast cancer, Professionals (157.6) showed highest ASR. Also, thyroid cancer in female showed high ASR in Professionals (101.7) and Legislators, senior officials, and managers (114.4).

Conclusion Cancer incidence by occupations were different depending on cancer site. Thyroid cancer and breast cancer were increased in occupations with high socioeconomic position, which can be related to accessibility to cancer screening. Male lung cancer increased in occupations in which there is potential exposure to harmful materials. It is needed to perform further study on cancer incidence rates of workers related to complex factors including socioeconomic factors and work-related ones