UroToday.com- In the online edition of Cancer, Dr. Gong and associates from Seattle, Washington report on a population-based cohort of middle-aged men that links obesity at the time of diagnosis with increased risk of prostate cancer (CaP) metastasis and death.

This study differs from others that associate obesity with CaP outcomes in that the participants included all men without consideration of treatment, stage or grade. Included in the database were 752 men with newly diagnosed CaP who participated in a population-based, case-control study and were enrolled from 1993-1996. These men completed an in-person interview and detailed information was collected on demographic and lifestyle characteristics, and family history of CaP. Patients self-reported height and weight, and body mass index (BMI) was stratified into normal (BMI <25kg/m2), overweight (BMI 25-29.9kg/m2), and obese (BMI >30kg/m2). Gleason scores were obtained from biopsy reports (30%) or surgical pathology (70%). Cancer stage was defined according to SEER criteria as localized, regional or distant. When primary therapy was used as a covariate, categories were radical prostatectomy (RP) without androgen deprivation therapy (ADT), RP with ADT, radiotherapy without ADT, radiotherapy with ADT, watchful waiting, and ADT alone. A follow-up survey was sent to all living men in January 2004 to collect social, demographic, and clinical information. A total of 520 returned data. The mortality endpoints were CaP-specific mortality and other-cause mortality. Of the 752 men in the study, 50 died of CaP and 64 died from other causes.

The data revealed that most participants were Caucasians, 60% were < 60 years at diagnosis, 16% currently smoked, 27% had regional or distant disease at diagnosis, 14% had Gleason scores >7, 63% were treated with RP, and 72% had a PSA level >4.0ng/ml at diagnosis. The mean BMI was 26.7kg/m2 and 17% were classified as obese. There were no significant associations between obesity and prognostic variables, but obese men were less likely to undergo RP and were more likely to have ADT added to RP or radiotherapy. After controlling for age, race, and clinical prognostic factors at baseline, obesity was associated with a hazard of CaP mortality of 2.64 relative to men of normal BMI. The association of obesity with CaP-specific death was modestly associated with higher Gleason score or localized stage at diagnosis. There existed a suggestion that the HR was greater among men who did not receive ADT, and the interaction testing ADT vs. no ADT was not statistically different. Overall, the risk of metastasis increased with higher BMI and obese men had a 3.61 relative hazard of metastases compared with men of normal weight.

Zhihong Gong, Ilir Agalliu, Daniel W. Lin, Janet L. Stanford, Alan R. Kristal

Cancer 2007; 109(6) March 2007, 1192-1202

Reviewed by UroToday.com Contributing Editor Christopher P. Evans, MD

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