Posted on May 13th, 2013 by
A new genetic test—the Oncotype DX® Prostate Cancer Test—measures the aggressiveness of prostate cancer and may help scores of men choose between immediate treatment or active surveillance. The test was shown to strongly predict aggressiveness of disease in a validation study presented at the 2013 annual meeting of the American Urological Association in San Diego, California. The test is now available to patients.
Each year in the United States, more than 240,000 men are diagnosed with prostate cancer and more than 27,000 die of the disease. Prostate cancer is typically a disease of aging. It may persist undetected for many years without causing symptoms. In fact, most men die with prostate cancer not from prostate cancer. Approximately 20% of men will develop prostate cancer during their lifetime, yet only 3% will actually die of the disease.
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 Genomic Prostate Score (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.
The validation study led by researchers at the University of California, San Francisco (UCSF) included 395 patients whose GPS was assessed using tissue from a single needle biopsy. The results indicated that the information provided by the GPS significantly increased—tripled, in fact—the number of patients identified as having low-risk disease who were thus eligible for active surveillance rather than treatment. What’s more, approximately 10 percent of patients originally classified as very low or low risk by clinical factors were identified by GPS as having more aggressive disease, which would be considered for immediate treatment.
The researchers concluded that the Oncotype DX GPS strongly predicted disease aggressiveness, offering information beyond currently available clinical factors, such as PSA and biopsy Gleason Score, to help physicians and their prostate cancer patients confidently choose the most appropriate treatment based on an individualized risk assessment. What’s more, the test has been validated to guide treatment decisions with the prostate needle biopsy sample—meaning low-risk patients could avoid invasive treatments such as surgery or radiation. The test is now available to patients and the researchers speculate that it could increase the use of active surveillance and help avoid overtreatment.
Cooperberg M, Simko J, Falzarano S, et al. Development and validation of the biopsy-based genomic prostate score (GPS) as a predictor of high grade or extracapsular prostate cancer to improve patient selection for active surveillance. Presented at the 2013 annual meeting of the American Urological Association. May 4-8, 2010. San Diego, CA. Abstract 2131.
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