The associations between colorectal cancer risk and several chronic illnesses, operations and various medications were examined in 715 colorectal cancer cases and 727 age- and sex-matched controls in data derived from a large, comprehensive population-based study of this cancer conducted in Melbourne, Australia. There was a statistically significant deficit among cases of hypertension, heart disease, stroke, chronic chest disease and chronic arthritis and a statistically significant excess of 'haemorrhoids' among cases, and all of these differences were consistent for both colon and rectal cancers and for both males and females. Although no statistically significant differences were found for other cancers, there were twice as many breast cancers among cases (16) than among controls (8) and also there were 9 uterine cancers among cases and only 2 among controls. There was a statistically significant deficit among cases in the use of aspirin-containing medication and vitamin supplements and this was consistent for both colon and rectal cancers and for both males and females. There was a statistically significant excess of large bowel polypectomy among cases. The modelling of these significant associations simultaneously in a logistic regression equation indicated that hypertension, heart disease, chronic arthritis and aspirin use were each independent effects and consistent for both colon and rectal cancers for both males and females and also that these effects were independent of dietary risk factors previously described in the Melbourne study. The possible relevance of these findings towards an understanding of colorectal cancer risk and aetiology is discussed.

If causality is assumed, we estimate that risk of colorectal cancer in the U.S. population could be reduced about 31% (50,000 cases annually) by an average increase in fiber intake from food sources of about 13 g/d, corresponding to an average increase of about 70%.

As part of a large-scale investigation of colorectal cancer (CRC) incidence, etiology, and survival, a case-control study was conducted to identify dietary factors associated with the risk of CRC. The study compared 715 cases with 727 age- and sex-matched community controls. A quantitative diet history, assessed to be the most representative of the previous 20 years, was obtained from each subject and analyzed for both food groups and nutrients. The combination of a high-fiber and high-vegetable intake was found to be protective against large bowel cancer. Cruciferous vegetable intake was also found, although with less certainty, to be protective. Dietary vitamin C was protective for estimated intakes greater than 230 mg/day. Dietary Beta-carotene had no separate association with the risk of CRC. Beef intake was a risk factor in males but not in females. Fat intake was a risk factor for both males and females. A low intake of milk drinks was a risk for both males and females. A high intake of pork and fish was protective. The use of vitamin supplements was highly protective. A risk score, which was calculated as the number of risk factors an individual has in his or her diet, showed an increasing monotonic relationship with risk of CRC. The effects of the dietary variables were similar for colon and rectal cancer and, with the exception of beef, were similar for males and females.