Diabetes not linked with prostate cancer death

By David Douglas

NEW YORK (Reuters Health) - Obesity, rather than diabetes, increases the risk that men being treated for locally advanced prostate cancer will die from the cancer, researchers report.

Obesity is known to be associated with an increased prostate cancer mortality risk -- and most men with diabetes are obese. Therefore, diabetes has been thought to be the underlying condition "responsible for greater risk of death from prostate cancer," Dr. Matthew R. Smith explained to Reuters Health.

However, he said, "In this study, we demonstrate that increased body weight, but not diabetes, is associated with greater prostate cancer mortality."

Dr. Smith of Massachusetts General Hospital, Boston, and colleagues reviewed data on more than 1500 men with locally advanced prostate cancer who were taking part in a clinical trial.

After follow-up for an average of more than 8 years, 210 of 765 deaths that occurred were attributed to prostate cancer.

After adjustment, diabetes was linked with significantly greater mortality from all causes and from non-prostate cancer.

In contrast, weight was associated with greater mortality due specifically to prostate cancer, but not with all-cause or non-prostate cancer mortality, the team reports in the Journal of Clinical Oncology.

For example, at 5 years, the mortality rate due to prostate cancer was 7.5 percent among men in the highest weight category compared to 4.1 percent among those in the lowest.

"These novel observations," continued Dr. Smith, "suggest that the association between obesity and prostate cancer mortality is not due to the metabolic alterations of diabetes."

More research is needed to uncover the reasons why obesity impacts deaths from prostate cancer, "including decreased effectiveness of standard prostate cancer treatments."

SOURCE: Journal of Clinical Oncology, September 10, 2008.