Weight may influence how prostate cancer is treated

NEW YORK (Reuters Health) - Obese patients with prostate cancer appear to be more likely to receive non-surgical treatments than their normal-weight counterparts, new research shows.

Obese patients with prostate cancer have more aggressive tumors, Dr. Benjamin J. Davies from the University of California, San Francisco, and colleagues note in the journal Urology, and prior studies have reported very high body mass index (BMI), the ratio of body weight to height, as a risk factor for death from prostate cancer.

The investigators looked at patients' BMI and compared it with the treatment they received for prostate cancer. The study included 2,041 men who were first treated between 1995 and 2006. A BMI of 18.5 to 24.9 is considered normal, 25 to 29.9, overweight, 30 to 34, obese, and 35 or greater, very obese.

A total of 28.1 percent of patients had a normal BMI, 50.5 percent were overweight, 16.5 percent were obese, and 4.8 percent were very obese.

Increasing BMI was associated with a greater likelihood of receiving nonsurgical therapies, such as chemotherapy or radiation therapy, rather than prostate removal.

Compared with normal-weight patients, very obese patients had a 77 percent greater chance of receiving hormone therapy and a 59 percent greater chance of receiving brachytherapy, a form of radiation therapy, as their main treatment.

Although hormone therapy may be a reasonable option for certain patients with early disease, this type of therapy cannot be considered a cure, which makes patients vulnerable to recurrence as well as side effects, Davies and colleagues note.

Brachytherapy, they note, is a reasonable treatment for patients with early-stage cancer and a low risk of disease spread, but not for intermediate- or high-risk patients.

There are many possible reasons for the link between higher body weight and use of non-surgical treatment, including a perception that obese patients have higher surgical complication rates, the team notes, although there are no data to support this.

"To our knowledge, this is the first study that examines the effect of BMI on patterns of treatment for prostate cancer," the authors note. Further research on patient and physician decision-making is needed to understand the reasons for the observed trends, they conclude.

SOURCE: Urology, August 2008.