• colon cancer;
  • rectal cancer;
  • physical activity;
  • occupational exposure


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

Methods. 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.

Results. 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.

Conclusion. 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.