New Insight on Weight Gain After Prostate Cancer Therapy

March 14, 2011 -- Many men with prostate cancer will get treatments to block male hormones like testosterone in an effort to keep their cancer from spreading.

There are several recognized side effects associated with those therapies, including hot flashes, loss of interest in sex, erectile dysfunction, bone loss, mood changes, and weight and body composition shifts. Body composition is a loss of muscle and bone mass with an increase in fat mass.

Now a new study shows that the weight gain -- about 9 pounds, on average -- associated with a form of hormone therapy called androgen deprivation therapy (ADT) appears to level off after the first year of treatment. It’s a finding that experts say is useful in helping doctors and patients who are trying to manage that extra girth, which studies have shown may increase the risks of diabetes and heart disease.

“The changes in body composition are a substantial side effect for which we don’t have a great solution yet,” says Philip J. Saylor, MD, instructor in medicine and a clinical oncologist at Massachusetts General Hospital, in Boston. “It’s helpful to know that it doesn’t lead to progressive changes throughout the course of a prolonged treatment. It’s helpful to know that most of the change happens early and that additional therapy doesn’t bring additional changes in body composition.” Saylor reviewed the study for WebMD but was not involved in the research.

The study’s researchers say the finding underscores the need for doctors to use these treatments, which include either surgical removal of the testes or drug therapy, conservatively.

“I’m using hormonal therapy a lot less than I was a few years ago because I do realize it is a very effective, albeit toxic therapy,” says study researcher Stephen J. Freedland, MD, associate professor at the Duke Prostate Center and a staff physician Veterans Affairs Medical Center, in Durham, N.C.

“There’s a growing body of data, to which our study contributes, that says there are clearly side effects with these therapies, so let’s make sure that there’s actually the possibility of benefit before we do this,” he says.