Colon Cancer in Women Linked with High Blood Sugar Levels

Colorectal cancer is the third most commonly diagnosed cancer, and the third leading cause of cancer death in the USA; that applies to both men and women.  Now a new study has found an association between raised blood sugar levels and colon cancer in older women.  It’s published online in the British Journal of Cancer.

The analysis, which was conducted by Albert Einstein College of Medicine researchers, used data from the Women’s Health Initiative who were enrolled starting at least 12 years ago.  There were 4,900 non-diabetic women who had fasting serum insulin and glucose measured at baseline.  Cases of colorectal cancer that developed during follow-up were recorded.

By the end of follow-up, 81 cases of colorectal cancer were recorded.  When the women were classified into one of three groups according to their blood glucose level at baseline those in the highest third, or tertile, were nearly twice as likely to have developed colorectal cancer as the women in the lowest tertile of fasting blood glucose levels.  (The highest tertile in this collective was women with fasting blood sugar levels at least 99.5 mg/dL, while the lowest tertile had levels below 89.5 mg/dL or more.)  There were similar findings when the researchers looked at repeated blood sugar levels over a period of time.  No associations were found between fasting insulin levels and the risk for colorectal cancer.

As obesity is a known risk factor for colorectal cancer, and is usually accompanied by increased levels of blood glucose and insulin, the finding of a lack of association between insulin levels and cancer frequency in this study was a surprise. Researchers will now have to look for another possible mechanism for the association of blood sugar with colon cancer.  One suggestion is that growth factors and/or inflammatory factors may play a role.  Whatever is found, it will certainly advance our knowledge of the underlying mechanism(s) for the onset of colorectal cancers, a worthwhile subject for research.