ASCO GU 2017: Evaluation of the Decipher prostate cancer classifier to predict metastasis and disease-specific mortality from genomic analysis of diagnostic prostate needle biopsy specimens

Orlando, Florida USA (UroToday.com) In this session, Dr. Nguyen discussed the Decipher genomic test and its role in predicting metastasis and prostate cancer specific mortality (PCSM) from diagnostic prostate needle biopsy specimens. Decipher is a 22 gene RNA-based signature developed to predict risk of metastasis after radical prostatectomy. In this context, it has been used to better stratify patients who may benefit from adjuvant radiotherapy. However, a reasonable question is whether the Decipher genomic test can be moved earlier in the sequence from diagnosis to treatment.

The main purpose of Dr. Nguyen’s study was to evaluate whether the Decipher genomic classifier determined from biopsy specimens is prognostic for metastases and PCSM in a mixed cohort treated with radical prostatectomy (RP) or radiation therapy (RT) with androgen deprivation therapy (ADT). The study cohort was comprised of 175 patients (100 RT+ADT and 75 RP). Stratified by National Comprehensive Cancer Network (NCCN) risk category, 13.1% were low risk, 50.9% were intermediate risk, and 33.7% were high risk. The median follow-up was 6 years during which there were 32 metastases and 11 prostate cancer deaths. High risk on the genomic classifier was defined as 0.6 or higher and low risk was defined as 0.4 or below.

The 5-year metastasis rate by decipher score was 23.4% for high risk, 9.3% for intermediate risk, and 5.0% for low risk. Among NCCN low and intermediate risk patients, the 5-year metastasis rate by decipher score was 33.1% for high risk, 11.0% for intermediate risk, and 1.2% for low risk. The 5-year PCSM rate by decipher score was 9.4% for high risk and 0% for both intermediate and low risk. The low number of mortality events (n=11) precluded evaluation in a multivariable model. Nonetheless, a hazard ratio of 1.57 (95%CI 1.07-2.4, p = 0.02) was noted on univariate analysis for every 10% increase in decipher score.

Dr. Nguyen closed by advocating for testing the prognostic significance of Decipher on prostate needle biopsy specimens in the context of clinical trials where questions regarding whether treatment modality effects metastasis-free survival or PCSM stratified by Decipher risk group can be addressed.

First author: Paul Nguyen

Written By: Benjamin T. Ristau, MD, Society of Urologic Oncology Fellow, Fox Chase Cancer Center

at the 2017 Genitourinary Cancers Symposium - February 16 - 18, 2017 – Orlando, Florida USA

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