Obesity Linked to Prostate Cancer Death Rates
MONDAY Nov. 12, 2007 -- In another sign that too much weight spells health problems, new research suggests that fat men are twice as likely to die after being diagnosed with prostate cancer than men of normal weight.
The research doesn't confirm a cause-and-effect link between obesity and a higher risk of death from prostate cancer, and it's not clear if losing weight would help patients after they're diagnosed with the disease.
Still, "if you look down the list of factors that are most predictive of a bad outcome, this [excess weight] ranks up there pretty high," said study co-author Dr. Matthew R. Smith, an oncologist at Massachusetts General Hospital in Boston.
According to the Prostate Cancer Foundation, the disease strikes one in six American men and is the most prevalent form of non-skin cancer in the United States. Risk rises with age, with more than 65 percent of all cases diagnosed in men over the age of 65.
However, prostate cancer can successfully be treated in many cases, particularly if it's caught early.
In the new study, Smith and his colleagues examined the results of men with advanced prostate cancer who were enrolled in a drug study between 1987 and 1992. The researchers looked at 788 men whose weights were recorded at the time of diagnosis to see if their body mass index -- BMI, a ratio of weight to height -- affected their risk of dying.
The researchers found that 6.5 percent of men with normal or low weight -- a BMI of less than 25 -- died from prostate cancer within five years. But the death rate for overweight men (a BMI of 25 to 30) was 13.1 percent, and it was 12.2 percent for obese men (a BMI of 30 or higher).
The higher rate of death remained constant even when the researchers adjusted their findings for other possible factors.
The study results are published in the Nov. 12 online issue of the journal Cancer.
It remains unclear why there might be a link between obesity and death rates from prostate cancer. It's possible that metabolism rates in heavy men might make the cancer more aggressive, Smith said, or obesity could render treatments less effective.
Dr. Martha K. Terris, a professor of urology at the Medical College of Georgia, who's familiar with the study findings, said hormone balance could be another factor. "Obesity changes the proportion of estrogen and testosterone in the blood, and this change may impact on the cancer behavior," she said.
Terris added that "obese individuals generally eat more high-fat diets with less fruits and vegetables that could contain key vitamins that help control cancer growth."
For now, Smith said, "the part we can't know is whether improvements in lifestyle intervention after prostate cancer diagnosis would improve outcomes."
Still, it would be wise for doctors to tell their patients about the apparent link between weight and prostate cancer death rates, Smith said. "This may be a teachable moment that prompts a discussion about general health considerations," he said.
In a related study published in Cancer, University of Michigan researchers found that families coping with prostate cancer reported improved quality of life from a structured support program integrated into the patients cancer management. The study, led by Dr. Laurel Northouse, found that patients and their spouses who participated in a five-session home counseling program reported significant improvement in such areas as symptom management, hope, uncertainty and the couples' communication.
For advice on losing weight, visit the U.S. Food and Drug Administration.
Posted: November 2007