Obesity has been linked to an overall increase in developing cancers of the breast, colon, endometrium (uterine lining), kidney, esophagus and liver. Studies have shown that excess body weight is associated with an increased risk of developing breast caner in postmenopausal women. Surprisingly the opposite is true with premenopausal women. Obesity is associated with higher estrogen levels in the blood and breast tissue and post menopausal women are more likely to have breast cancers which are stimulated by estrogen then with premenopausal women. Another suspected link between obesity and cancers is the insulin-like growth factor. Obese individuals tend to have higher insulin levels. These higher insulin levels cause the tissues to become resistant to the effects of insulin. Furthermore, there is a presence of insulin-like growth factors that are known to stimulate the growth of some cancers. A study of nearly 4000 women treated for breast cancer in the early 1980’s showed obesity was associated with an increased risk of breast cancer recurrence and death from breast cancer. However, it was also found that use of adjuvant chemotherapy or hormonal therapy diminished this risk. The benefit of weight loss after breast cancer is not well known, but until more evidence is gained, most breast cancer specialists advise against weight gain after developing breast cancer. The link between obesity and endometrial, colon (primarily men), kidney, pancreatic and hepatocellular cancers is thought to be related to increased estrogen or insulin levels. In esophageal cancer, obesity and the promotion of cancer is more likely due to an increased risk and severity of acid reflux from the stomach into the esophagus. Interestingly, obesity is associated with a decreased risk of developing prostate cancer. On the down side, men who have had treatment for prostate cancer, have a greater risk of recurrence as measured by a rising prostate specific antigen (PSA). Obesity and cancer risk has been studied far more than the effects of individual foods, nutrients, food additives, and exercise. This is in part because of the difficulty of performing dietary studies. Fortunately much interest in this field will likely yield more information in the future. Obesity and Cancer, An Ounce of Prevention, by Robert McCroskey, MD, published in Climbing R.O.P.S., Dec. 2005, p. 2.