By: Dan Sperling, MD
You would hardly think we need another reason to maintain healthy weight, but the threat of prostate cancer should add incentive. For overweight prostate cancer patients, losing weight before AND after treatment might save your life. Numerous clinical studies make this increasingly clear.
The studies explore two areas: a) the connection between obesity and higher Gleason grade and b) the increased risk for obese patients to have disease recurrence after treatment.
In the first category, being overweight falls into a group of genetic, ethnic and environmental factors associated with more dangerous cell lines of prostate cancer. A big red flag is obesity, calculated as a high body mass index, or BMI. (See http://www.nhlbi.nih.gov/guidelines/obesity/BMI/bmicalc.htm for an easy calculator.) A normal BMI falls in the 18.5-24.9 range. Obesity is 30 or higher, and between normal and obese is considered overweight. While obesity alone has not been proven to increase the incidence of prostate cancer, it is connected with higher death rates from prostate cancer—in other words, higher risk disease for fat men than for their thinner counterparts.
The second type of study links obesity with higher rates of recurrence after treatment. This makes logical sense, because more aggressive disease upon diagnosis means a greater chance of a positive surgical margin at the time of prostatectomy, leaving cancer behind. But it goes deeper than that. No one is sure of how obesity impacts the natural history (progression) of cancer, but some theories have to do with hormonal alterations. Leptin is a circulating hormone that seems to increase with higher BMI, and leptin appears related to angiogenesis, or the production of new blood vessels that a tumor needs to bring itself oxygen and nutrients. Obesity often leads to elevated blood levels of insulin and insulin growth factor that can stimulate the growth of both normal and tumor cells in the prostate, and may contribute to disease progression. These are just a couple of examples, but you get the point.
Perhaps you’re thinking, I’m not obese—I just carry a few extra pounds around my middle. Did you know that belly fat is basically early obesity? Try this simple test. Take a belt, and buckle it around your abdomen just at the very top of your hip bones, a few inches below your navel. Now remove it, and buckle it again just above your navel. If you had to loosen it beyond what it was at your hip line, now is the time to both improve the quality of your diet (less fat, less red meat, less sugar, less acohol, more raw whole foods and lean meats in smaller quantities) and increase your level of exercise. Slow but steady weight loss is an investment in your overall health, your prostate health, and your longevity.