Rate of gain, obesity factor into increased risk for prostate cancer recurrence

09/30/05

PHILADELPHIA -- Men who gain weight rapidly between the ages of 25 and 40 are twice as likely to have recurrence of prostate cancer after surgery as men without rapid rates of weight gain, researchers from UT M. D. Anderson Cancer Center reported in the October 1 issue of "Clinical Cancer Research."

Patients who are obese at age 40 and at time of diagnosis with prostate cancer also have a higher risk of recurrence, the research indicated.

"Patients who gained an average of three and a half pounds a year have an increased risk for having their prostate cancer recur," said Sara S. Strom, Ph.D., associate professor, department of Epidemiology, the University of Texas M. D. Anderson Cancer Center, Houston, Texas.

"They are more likely to experience biochemical failure, which is when their PSA level rises, and their failure is likely to come sooner after surgery than in men who did not gain weight rapidly, or who were not obese."

PSA, or prostate specific antigen, is a protein produced almost exclusively by the prostate. It is a screening marker, measured in blood, that when elevated to over four nanograms per milliliter is a signal for men and their clinicians to consider pursuing additional screening, such as needle biopsies.

After removal of the prostate gland, the PSA level should be undetectable, Strom added. However, men who gained weight the fastest after age 25 were more likely to experience biochemical failure, which is the increase of PSA levels in the blood after removal of the prostate gland, the primary source of this protein. Obese patients had elevated PSA levels much sooner after surgery 12 months earlier than their lighter counterparts.

In a study of 526 patients, men who gained weight faster between age 25 and the time of diagnosis of their prostate cancer were at greater risk for recurrence of the disease than men who gained weight more slowly or who were not obese, said Strom. The men at greater risk gained an average of 1.5 kilogram per year, or about three and a half pounds per year. Thus, a man who weighed 150 pounds at age 25 but weighed over 200 pounds by age 40 would be at a higher risk for recurrence if he develops prostate cancer.

Strom's study also identified that men who were obese at age 40 had twice the likelihood of biochemical failure after surgery than non-obese men. Strom and her colleagues considered obesity to conform to the conventional medical indexing called 'body mass index,' which is a patient's weight divided by the square of his height. For example, a 200 pound man who is five-foot nine-inches tall has a body mass index of 30 and is considered obese within the guidelines of this study.

The incorporation of body mass index at time of diagnosis with other measures of prostate cancer progression, such as PSA levels prior to surgery, age, stage of progression, Gleason Score, or tumor cell invasion of lymph nodes or seminal vesicles, enhances the predictive value of tools used to determine the risk each patient has for recurrence of prostate cancer.

"Urologists and oncologists can use this information when a man is diagnosed with prostate cancer to develop treatment strategies for that patient," Strom said. "By plugging in the clinical characteristics, they calculate each patient's risk of having more aggressive disease that will progress," she noted. "Body mass index makes that information more precise."

Source: Eurekalert & others

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