Do occupational factors influence the risk of colon and rectal cancer in different ways?

Occupational exposures and physical activity have been considered as risk factors for the development of colorectal cancer.

A case-control study on working conditions and the risk of colon and rectal cancer was performed in southeastern Sweden during 1984-86. Involved were 177 patients, 98 with colon cancer and 79 with rectal cancer, and two groups of control subjects, 371 hospital control subjects and 430 population control subjects.

A significantly decreased risk of left-sided colon cancer was observed in persons involved in more than 20 years of physically active work and a significantly decreased risk of rectal cancer in persons involved in more than 20 years of sedentary work. A tendency toward increased risk was seen for colon cancer in male railroad workers and in male gas station workers. A reduced risk of rectal cancer was found for drivers, textile workers, and administration workers, whereas an increased risk of rectal cancer appeared among paper workers and assistant nurses. A low risk of both colon and rectal cancer was found among construction workers and forestry workers. Exposure to asbestos carried a slightly increased risk of colon cancer, whereas exposure to solvents slightly decreased the risk of rectal cancer.

This study confirms earlier findings that physical activity decreases the risk for left-sided colon cancer, but also suggests that occupational factors influence the risk of colon and rectal cancer in different ways.