Use Of DNA Methylation To Predict The Absence Of Prostate Cancer In Men With High Risk And Initially Negative Prostate Biopsy

Main Category: Prostate / Prostate Cancer
Also Included In: Urology / Nephrology;  Genetics
Article Date: 24 Feb 2008 - 0:00 PDT

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UroToday.com - Dr. Trock addressed the fact that 30% of patients with a negative initial prostate biopsy will be found to have CaP on repeat biopsy. They sought to develop a test to identify men who would not need a repeat biopsy. High risk features for a positive biopsy were reviewed (both PSA based and pathological such as high PSA, HGPIN, and atypia).

DNA methylation markers such as GSTP1 and APC methylation have high specificity and sensitivity and may improve upon histology alone. Men with negative initial histological biopsies were studied. A total of 86 men made up the study cohort. All men had high risk features and underwent a repeat 12-core prostate biopsy. GSTP1 and APC methylation status on initial biopsy tissue was compared to the repeat biopsy.

Methylation ratio was low in the high PSA and HGPIN groups, and the false negative rate was 14-15%. In the atypia group the false negative rate was 42%. APC methylation ratio was higher for high PSA, HGPIN and atypia. The false negative rates were 0%, 0%, and 20% respectively for the high PSA, HGPIN and atypia risk groups. The negative predictive value of the first biopsy was 76%. Excluding atypia, for which Dr. Trock argued the urologist would likely want to re-biopsy anyways, the negative predictive value of the combined methylation ratio test is 96-100%. The prevalence of cancer on the second biopsies was 24%. The results suggest that 30% of men would avoid a repeat biopsy by using this approach.

Presented by B.Trock at the American Society of Clinical Oncology (ASCO) - 2008 Genitourinary Cancers Symposium - A Multidisciplinary Approach - February 14-16, 2008 San Francisco, California, USA

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