Utility of Oncotype Dx in Men with Intermediate-Risk Prostate Cancer
The Oncotype Dx Genomic Prostate Score (GPS) Assay is a commercially-available assay from Genomic Health (GH) designed to help guide treatment in men diagnosed with clinically low-risk prostate cancer (PCa) or &[Prime]select&[Prime] cases of intermediate-risk disease. We retrospectively investigated the use of this test in practice and assess its role in clinical management at an urban tertiary care academic center.
All Oncotype Dx reports received on prostate biopsies sent from our institution to GH from May 2015 to September 2017 were reviewed. Changes to the patient&[prime]s NCCN risk group (very low risk [VLR], low risk [LR], or intermediate [INTR]) as a result of the addition of the GPS were recorded. Disease management decisions were also obtained.
A total of 114 men had Oncotype Dx testing, of which 108 had sufficient tissue for the assay. On biopsy, 64% (69/108) had Grade Group 1 PCa and 36% (39/108) had Grade Group 2 PCa. By NCCN guidelines, 24% (26/108) were VLR, 31% (33/108) were LR, and 45% (49/108) were INTR. After addition of GPS to the NCCN risk group, 20% (22/108) changed risk groups. None (0/26) of the VLR group changed to a higher risk group, 36% (13/33) of the LR group changed groups (9 to VLR, 4 to INTR), and 20% (10/49) of the INTR group became LR. Treatment information was available in 93 men. Of the 10 INTR patients by NCCN who changed to a lower risk group after Oncotype testing, 80% (8/10) elected active surveillance (AS), 10% (1/10) underwent radical prostatectomy (RP), and 10% (1/10) chose focal therapy. Of the 39 INTR men who remained in the same risk group, 34 had treatment information. 38% (13/34) underwent RP, 35% (12/34) selected AS, 15% underwent radiation therapy (RT), and 11% (4/34) received focal therapy. Of the 4 men who changed from LR to INTR by the addition of GPS, 2 were definitively treated and 2 selected AS.
Nearly half of the GPS assays at our institution were requested on patients who were INTR by NCCN guidelines, and of these, 80% remained in the same risk group following the addition of GPS. Considering the cost of this supplemental assay and that the test changes the risk group for only a minority of men, testing should be reserved for patients in whom the molecular analysis will alter their treatment decisions.