Data are mixed on impact of obesity on prostate cancer.
Another two studies presented at the meeting--on men being treated for prostate cancer--produced somewhat conflicting results regarding weight, with one study finding worse outcomes in obese patients compared with normal-weight patients and the other saying that obesity was not associated with a higher risk for progression of the cancer.
The differing results may be partly attributable to the designs of the studies, which looked at different patient populations (undiagnosed, newly diagnosed, or patients undergoing treatment) and used different definitions of disease survival or progression, Stephen J. Freedland, M.D., a principal investigator in one of the studies, noted during a press briefing.
The findings may give patients who are concerned about an elevated prostate-specific antigen (PSA) level an added reason to pursue weight loss as a preventive health measure, said Judd Moul, M.D., who moderated the briefing.
"We as doctors need to become more willing to tell people that they're fat," said Dr. Moul, director of the urologic oncology clinic at Walter Reed Army Medical Center, Washington.
Here are the highlights of the studies:
Men with a normal body mass index were more likely to be diagnosed with prostate cancer and had larger cancers, compared with overweight or obese men, in a retrospective analysis of 787 consecutive patients who underwent prostate biopsy after referral for an abnormal digital rectal exam and/or a PSA level above 4 ng/mL.
When patients were stratified by age, this finding was true for men aged younger than 70 years but not for older men, said Joseph C. Presti Jr., M.D., of Stanford (Calif.) University.
The results support findings from a previous longitudinal, population-based study of nearly 29,000 men that suggested obesity may protect against development of organ-confined disease. This does not mean that it's okay to be obese, he cautioned. Obesity may be associated with more advanced prostate cancer.
A separate study found that among 3,684 men treated for prostate cancer between 1989 and 2002, overweight men tended to present with lower-risk disease compared with normal-weight men. The chances of presenting with high-risk disease increased in obese men and increased further in very obese patients, said Christopher J. Kane, M.D., of the University of California, San Francisco.
The mixed findings suggest that the lower-risk cancer found in overweight men is due to an early-detection bias. Obese men were younger than normal-weight men and more likely to have hypertension, diabetes, and other comorbidities, and probably saw physicians more often. The results support a biologic mechanism for more aggressive prostate cancers in obese men, he added.
Another study of 1,106 men who underwent radical prostatectomy for clinically localized prostate cancer between 1988 and 2002 found that obese patients had higher-grade tumors and were more likely to develop recurrences defined by PSA levels within 3 years, said Dr. Freedland of Johns Hopkins University, Baltimore. But a retrospective study of 2,595 patients undergoing radical prostatectomy for localized prostate cancer--354 of whom developed PSA progression of disease after treatment--found no association between body mass index and disease progression in up to 180 months of follow-up, reported Michael W. Kattan, Ph.D., of Memorial Sloan-Kettering Cancer Center, New York.
BY SHERRY BOSCHERT
San Francisco Bureau
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|Title Annotation:||Across Specialties|
|Publication:||Clinical Psychiatry News|
|Date:||Apr 1, 2005|
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