Nutrition Notes: Obesity, Diabetes and Prostate Cancer: What’s the Link?

by Karen Collins, MS, RD, CDN | Kansas City InfoZine | 12.15.2008

According to experts, excess body fat does not raise your chances of getting prostate cancer. But studies show that obese men who develop the disease are more likely to die from it.

Consequently, interventions to prevent weight gain in the first place may increase survivorship. Now, emerging research suggests that high insulin levels, common among overweight men, may also play a role in increasing fatalities among those diagnosed with prostate cancer. If confirmed, the finding would have important implications for how we treat the disease.

The new findings are particularly interesting because men who have diabetes a disease usually marked by excess weight and high insulin levels seem to be at reduced risk of developing prostate cancer. Data from the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial, which followed more than 33,000 men for almost nine years, were released earlier this year and noted that men who had diabetes showed a 20 percent lower risk for non-aggressive, early stage prostate cancers.

These findings might seem to contradict theories that high levels of insulin often associated with diabetes can promote growth of prostate cancer. Why then, might diabetes show an opposite protective effect? For starters, high insulin levels due to insulin resistance usually develop years before the most common form of diabetes is diagnosed. In the years after diagnosis, insulin levels may start to fall.

The new study, published in the Lancet Oncology, followed 2,500 men for 24 years. According to the researchers, the link between excess weight and death from prostate cancer held up again: Compared to healthy weight men, men who started the study overweight were 47 percent more likely to die from prostate cancer. Men who were obese at the start of the study were two-and-a-half times more likely to die from the disease.

In addition, men who showed higher insulin production when the study began had more than twice the risk of dying from prostate cancer years later. Men with both of these risks being overweight or obese men and having high insulin levels were four times as likely to die from the disease as men with a healthy weight and low insulin levels.

We need further studies to confirm the insulin link, but researchers say this study opens the door to new approaches to treating prostate cancer. Treatment might address insulin levels as well as male reproductive hormones that are currently a major focus of treatment. This may be especially important since even three to six months of hormone deprivation therapy results in elevated levels of insulin in the blood.

Meanwhile, researchers say that these studies do provide more motivation for men to maintain a healthy weight and keep physically active every day. Avoiding unhealthy insulin elevations is already a healthy move; if prostate cancer can become less of a threat, then that’s a bonus.

Copyright Kansas City InfoZine 2008