ASCO GU 2018: Impact of Genomic Risk Scores on Treatment Decisions Following Radical Prostatectomy in a Prospective Medicare Registry

San Francisco, CA (UroToday.com) There is growing evidence that genomic classification of malignancies, including prostate cancer, may help overcome the heterogeneity and inherent subjective flaws of clinical staging systems. There are many genomic tests for prostate cancer that address prostate cancer in its various clinical stages. Some are based on prostate biopsy tissue, while others are based on prostatectomy or metastatectomy specimens.   

The authors specifically assess how the addition of a genomic classifier, such as a Decipher, which has been demonstrated to predict metastases risk after RP, effects the physicians’ decision-making regarding post-operative radiotherapy – either adjuvant (ART) or early salvage XRT (SRT).

Over an 8-month period, 1,319 men treated with RP who were considering ART or SRT were enrolled at multiple institutions. Physicians submitted a recommendation based on initial clinical and pathology findings prior to obtaining the Decipher RP test and again upon receiving test results. Only men with non-organ confined prostate cancer, positive margins or rising PSA were included in the analysis. Unfortunately, it should be noted, a patient with a rising PSA post-RP is technically already past the adjuvant classification – hence, their definition may be incorrect.

A total of 517 patients were finally included. In terms of demographics, median age was 69, 27% were GG 4-5, 58% had positive surgical margins, 74% extraprostatic extension, 25% seminal vesicle invasion, and 80% were pT3+. In terms of Decipher risk, 31% were low-risk, 24% were intermediate risk, and 45% were high-risk.

Prior to obtaining the test, based on clinical variables alone, ART was recommended for 26% of men and SRT for 19% of men. After obtaining a Decipher score, treatment recommendations changed in 34% (95% CI 30-39%) and 28% (95% CI 19-38%) of men considering ART or SRT, respectively. Approximately 1/3 of men had a treatment recommendation change.

Multivariable logistic regression demonstrated that – independent of pathology risk factors, a high-risk Decipher score was associated with the decision to pursue treatment (compared to low-risk Decipher score); OR 7.3 (95% CI 3.9-14.2 p < 0.001) in the adjuvant and 5.5 (95% CI, 1.3-27.8, p = 0.026) in the salvage setting. RP GG, Surgical margins, EPE and SVI were not associated with decision to pursue treatment.

Importantly, the authors note that while the current study does not address oncologic outcomes with altered treatment based on the Decipher score, ongoing prospective studies are assessing how increased use of therapy in men with high Decipher scores impacts oncologic outcomes and whether decreased use in Decipher low risk individuals improves health related quality of life without harming patient survival.

This will provide us with more concrete knowledge regarding the utility of the Decipher score in more routine practice.

Speaker: John Gore, MD, MS

Co-Authors: Darlene Dai, Robert Benjamin Den, Kasra Yousefi, Tiffany Le, Marguerite Du Plessis, Roanna Padre, Worlanyo Sosu-Sedzorme, Elai Davicioni, Paul L. Nguyen, Ashley Ross

Institution(s): University of Washington School of Medicine, Seattle, WA; GenomeDx Biosciences Inc., Vancouver, BC, Canada; Sidney Kimmel Medical College at Thomas Jefferson University, Philadelphia, PA; GenomeDx Biosciences Inc., San Diego, CA; Brigham and Women's Hospital/ Dana-Farber Cancer Institute, Boston, MA; Johns Hopkins Medicine, Baltimore, MD

Written by: Thenappan Chandrasekar, MD, Clinical Fellow, University of Toronto, Twitter: @tchandra_uromd at the 2018 American Society of Clinical Oncology Genitourinary (ASCO GU) Cancers Symposium, February 8-10, 2018 - San Francisco, CA
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