Based on findings from three separate studies, it appears that the 17-gene Oncotype DX® Genomic Prostate Score (GPS) can help predict disease aggressiveness in prostate cancer at the time of diagnosis and therefore help physicians choose appropriate treatment. The results of these studies were published in European Urology.
The treatment of early-stage prostate cancer is controversial because thus far there is no clear proof that aggressive treatment prolongs survival compared with deferred treatment. Furthermore, treatment can cause lasting side effects, such as impotence and incontinence. Some men opt for a more conservative approach, called active surveillance or watchful waiting—which defers treatment until symptoms appear and/or there is evidence of progression. This approach can help some men avoid unnecessary treatment and potentially long-lasting side effects; however, until now, it wasn’t possible to predict which cancers were aggressive and required treatment and which were slow-growing and could be watched until treatment was necessary.
The Oncotype DX prostate cancer test measures the level of expression of 17 genes across four biological pathways to predict prostate cancer aggressiveness. The test results are reported as a GPS that ranges from 0 to 100 and is combined with other clinical factors to further clarify a man’s risk prior to treatment intervention.
To determine whether Oncotype DX can reliably predict aggressiveness of prostate cancer and whether patients are likely for benefit from immediate treatment or deferred treatment, researchers compared findings from three prognostic procedures with predictions based on Oncotype DX. A total of 732 patient genes were studied. The prognostic procedures included:
- Prostatectomy (removal of prostate gland)
- Previously collected needle biopsy studies from patients considered low- to intermediate-risk and prescribed active surveillance
Prostate cancers in the three studies were considered “aggressive” in the event of a clinical recurrence, death from prostate cancer, or discovery of aggressive cancer after removal and study of the prostate (adverse pathology).
When the researchers compared predictions based on the Oncotype DX GPS with the three prognostic procedures, they found that that Oncotype DX could reliably predict aggressive disease, including recurrence. Specifically, 288 of the 732 genes analyzed, or almost 40%, reliably predicted recurrence; and 198 of 732 (almost 40%) reliably predicted aggressive disease.
Based these findings Oncotype DX appears to reliably predict the aggressiveness of prostate cancer at diagnosis. More reliable prognosis will allow physicians to better choose treatment; in other words patients at greater risk of aggressive disease can choose immediate treatment, whereas those at low risk can choose deferred treatment and avoid the side effects of potentially unnecessary intervention.
Klein EA, Cooperberg MR, Magi-Galluzzi C, et al. A 17-gene Assay to Predict Prostate Cancer Aggressiveness in the Context of Gleason Grade Heterogeneity, Tumor Multifocality, and Biopsy Undersampling. European Urology [early online publication]. May 16, 2014.
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