Dec. 22, 2006 -- Men who lose weight may be less likely to get aggressive prostate cancer, while obesity may increase a man's risk.
So say researchers, including Carmen Rodriguez, MD, MPH, of the American Cancer Society.
This study is the first to probe links between a man's adult weight change and prostate cancer risk.
In 1992, Rodriguez and colleagues asked nearly 70,000 U.S. men about their current weight and their weight 10 years earlier.
The researchers then tracked new prostate cancer cases among the men from 1992 to 2003.
Those who reported losing at least 11 pounds from 1982 to 1992 were about 40% less likely to develop aggressive (but nonmetastatic) prostate cancer between 1992 and 2003 than those with little weight change in the 1982-1992 time period.
Weight and Prostate Cancer
"Our study linking obesity to aggressive prostate cancer adds to increasing evidence of the importance of maintaining a healthy weight throughout life," Rodriguez says in an American Cancer Society news release.
"Although our study suggests that weight loss may lower the risk of aggressive prostate cancer, given the difficulty of losing weight, emphasis should be put on the importance of avoiding weight gain to reduce the risk of prostate cancer," she says.
Prostate Cancer Study
Most of the men who took part in the study were 55-74 years old in 1992. None had had cancer other than nonmelanomaskin cancer
The men reported their height and weight. Using those figures, the researchers calculated the men's BMI (body mass index), an indication of appropriate weight.
Nearly two-thirds of the men were overweight or obese in 1992. Thirty-six percent had normal BMI, 50% were overweight, and 14% were obese.
In 1992, most of the men -- 44% -- reported little weight change in the past decade, gaining or losing 5 pounds or fewer.
Twenty-one percent said they had lost more than 5 pounds, and 35% said they had gained 5 or more pounds between 1982 and 1992.
Tracking Prostate Cancer
By the middle of 2003, 5,252 men reported being diagnosed with prostate cancer. Most cases weren't aggressive.
Men who had lost weight between 1982 and 1992 were less likely to have been diagnosed with aggressive prostate cancer, the study shows.
The researchers' conclusion: "Men who lose weight may reduce their risk of prostate cancer."
The men reported their own weight and height; those measurements weren't confirmed.
The data don't show which men had been overweight or obese since childhood. So the lifelong influence of obesity on prostate cancer risk isn't clear from this study.
The researchers didn't assign anyone to lose weight, so this was an observational study rather than a direct test of weight loss for prostate cancer prevention.
The study appears online in Cancer Epidemiology Biomarkers & Prevention.
Men who want to lose weight should consult their doctor for advice.