Obesity May Be Protective in Progressive Prostate Cancer

NEW YORK NOV 16, 2007 (Reuters Health) - In men with progressive prostate cancer despite androgen deprivation therapy, higher body mass index (BMI) is associated with lower overall and prostate cancer-specific mortality, according to a report in the October 1st issue of Cancer.

Existing data suggest that obese prostate cancer patients have less favorable outcomes than their normal-weight counterparts, the authors explain, but few studies have investigated outcomes in men with progressive prostate cancer despite androgen deprivation therapy -- referred to by the authors as castration-recurrent prostate cancer (CRPC).

Dr. Susan Halabi from Duke University, Durham, North Carolina and colleagues investigated whether an elevated BMI predicted worse clinical outcomes in 1226 men with CRPC who were treated in 9 clinical trials between 1991 and 2004.

Less than a quarter of the men (24%) had normal BMI, the authors report, whereas 43% were overweight and 33% were mildly to severely obese.

Median overall survival was highest in mildly to severely obese men (16.9 months), lower in overweight men (16.1 months), and lowest in men with normal BMI (11.5 months).

The pattern was similar for the median time to prostate cancer-specific-death, the report indicates, which was 18.9 months for mildly to severely obese men, 17.6 months for overweight men, and 12.7 months for men with normal BMI.

"The findings from the current study suggest that obesity has an impact on clinical outcomes associated with CRPC, in contrast to earlier stages of prostate cancer," the authors conclude. "Further studies of the mechanisms underlying this correlation as well as a prospective validation of these results are warranted."

They hypothesize that in this population of men with advanced disease, "a lower BMI may reflect cancer cachexia and may serve as surrogate of more aggressive disease, leading to more rapid disease progression or less effective treatment."

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