24th Int'l Prostate Cancer Update: Abstract - Effect of a 22-marker genomic classifier assay on adjuvant radiation therapy recommendations in patients with high-risk prostate cancer

VAIL, CO USA (UroToday.com) - Background: Clinical guidelines recommend adjuvant radiation therapy (ART) be offered to patients with adverse pathology after radical prostatectomy (RP).

The Decipher® genomic classifier (GC) assay is a clinically validated predictor of metastasis risk in these patients. We performed a multicenter prospective decision-impact study to assess the effect of GC on urologists’ adjuvant treatment planning.

24th cap updateMethods: Under an IRB-approved study, US-board certified urologic oncologists (n=107) were asked to review from a pool of 122 case histories for patients treated by five of the study participants who had ordered the GC assay for eligible patients (pT3 or positive surgical margin disease, SM+). Presentation of cases was randomized to minimize recall bias. For each patient case physician respondents first were asked to render an adjuvant therapy plan without knowledge of the GC findings (pre-GC); they were then asked to render an adjuvant recommendation after GC findings (post-GC). Recommendations were made without knowledge of others’ responses.

Results: Eligible physicians (n=51) provided 530 adjuvant recommendations for 110 patients. Physicians represented 32 institutions across 19 US states. 52% were from community-based practices performing at least 40 RP/year. Median patient age was 62 years (range: 44-75); 71% had pT3 disease and 63% had SM+. GC classified 72% of these patients as low risk for metastasis; overall median 5 year predicted probability of metastasis was 3.85% (range: 1%-33%). Pre-GC, observation was planned for 57% (n=303) and ART for 36% (n=193). Overall, 31% of treatment plans changed post-GC (95% CI: 27-35%). Among ART plans pre-GC, 40% changed to observation (95% CI: 33- 47%; n=77), whereas for patients planned for observation only 13% (95% CI: 9%-17%; n=38) changed to ART post-GC. Patients with low GC risk were recommended observation 81% of the time (n=276), while those with high GC risk, 63% were recommended for treatment (n=118, p<0.0001). GC was also the predominant factor driving decisions in multivariable analysis (OR 7.73, 95% CI: 4.85-12.32, p<0.0001).

Conclusions: In this study, we found that similar to historical practice patterns in the US, urologists planned ART for 36% of high-risk patients. Additional knowledge of the tumor’s biological characteristics halved ART recommendations in patients assessed by GC to be at low risk for recurrence. Use of the GC assay may lead to reductions in treatment intensity after surgery for the majority of patients tested.

Presented by Ketan Badani, David Albala, Vladimir Mouraviev, Naveen Kella, Amar Singh, Gordon Brown, Daniel Holmes, Christine Buerki, Kasra Yousefi, and Darby Thompson at the 24th International Prostate Cancer Update- February 19 - 22, 2014 - Cascade Conference Center - Vail, Colorado USA

Columbia University Medical Center, New York, NY
Associated Medical Professionals, Syracuse, NY
The Urology and Prostate Institute, San Antonio, TX
Erlanger Medical Center, Chattanooga, TN
Delaware Valley Urology, Mt. Laurel, NJ
Kansas City Urology Care, Overland Park, KS
GenomeDx Biosciences Inc, Vancouver, BC
EMMES Canada, Burnaby, BC