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The Impact Of Obesity On The Diagnosis Of Prostate Cancer Using A Modern Extended Biopsy Scheme

Studies associating obesity and prostate cancer (CaP) are varied. In the February 2009 edition of the Journal of Urology, Dr. Raj Pruthi and colleagues reported on the impact of obesity in the detection of CaP. The study is a single institution series of 500 men with an increased or increasing PSA or abnormal DRE who underwent transrectal ultrasound guided biopsy of the prostate. All men had an extended 10 to 12 core biopsy, which makes this report relevant to present day standards. Clinical and pathologic parameters were evaluated. For the purpose of this study, body mass index (BMI) was categorized into non-obese (<30kg/m2) and obese (>30 kg/m2). This differs from many studies, in which the non-obese category would typically be further separated into normal (<25 kg/m2) and overweight (25-30 kg/m2).

The mean patient age was 63.4 years, mean BMI was 27.6 kg/m2, median PSA was 6.5ng/ml, and mean prostate volume was 50.4cc. Of the participants, 26% were considered obese. Forty-five percent had CaP on biopsy, but there was no difference in mean BMI between those with a positive vs. a negative biopsy. Obese men were younger, had larger prostates, were less likely to have an abnormality on DRE, and less likely to have a positive biopsy by chi square analysis. In multivariate analysis controlling for age, PSA and prostate volume, there was not a difference between non-obesity and obesity for detection of CaP. Also, modeling for high-grade Gleason score demonstrated no difference for BMI. In patients with negative biopsies, obese men had larger prostate volumes (p=0.033). The investigators did a subset analysis on 367 men with a PSA <10ng/ml and found no differences in the biopsy rates of obese vs. non-obese men.

While previous studies have demonstrated a higher CaP detection rate in obese patients by using an extended prostate biopsy scheme, this study did not find that obese men had a higher detection rate of CaP in multivariate analysis.

Pruthi RS, Swords K, Schultz H, Carson CC 3rd, Wallen EM
J Urol. 2009 Feb;181(2):574-7
10.1016/j.juro.2008.10.028