Higher BMI Increases PCa Death Risk

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Obese men had a 65% higher risk of dying after therapy for locally advanced tumors.

ORLANDO—Elevated BMI is independently associated with higher prostate cancer-specific mortality (PCSM) following radiation therapy and androgen suppression in men with locally advanced prostate cancer.

A study of this patient population showed that the five-year PCSM rate was 12.2% for men with a BMI of 30 kg/m2 and higher (obese), 13.1% for men with a BMI of at least 25 kg/m2 but less than 30 kg/m2 (overweight), and 6.5% for men who have a BMI less than 25 kg/m2 (normal weight).

Compared with normal weight men, overweight and obese men had a 52% and 64% greater risk of dying from prostate cancer, respectively, after adjusting for potential confounders. BMI was not associated with all-cause mortality or non-cancer death.

The researchers, led by Jason A. Efstathiou, MD, of the Harvard Radiation Oncology Program in Boston, studied 788 men with clinical stage T3 or node-positive malignancy and who had height and weight data available. The men were enrolled in a Phase III trial run by the Radiation Therapy Oncology Group (RTOG 85-31) between 1987 and 1992. The men were randomly assigned to receive radiation therapy plus immediate adjuvant goserelin or radiation therapy alone followed by goserelin only at relapse.

Dr. Efstathiou pointed out limitations of the study, including a lack of some information on patients' lifestyles and comorbidities associated with obesity. Another limitation was the absence of PSA values be-cause the trial was conducted before PSA testing became widely available.

The new study adds to a growing amount of evidence linking higher BMI to an increased risk of death from prostate cancer. For example, researchers who studied 752 middle-aged men with prostate cancer found that obese men (BMI of 30 kg/m2 or higher) were at 2.6 times greater risk of death from the malignancy, according to a recently published report in Cancer (2007; published online ahead of print).

In another study, also published recently in Cancer (2007;109:675-684), investigators found that, compared with men whose BMI was less than 25 kg/m2 at baseline, those with a BMI of 25-29.9 and 30-34.9 kg/m2 at baseline had a 25% and 46% in-creased the risk of death from prostate cancer, respectively. A baseline BMI of 35 kg/m2 or higher increased the risk twofold. The study also showed that adult weight gain from age 18 to baseline was associated with an increased risk of death from prostate cancer.

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