Genomic testing helps individualize treatment. This means that patients with more serious conditions can be identified and offered aggressive and innovative therapies that may prolong their lives, while patients who are diagnosed with a less serious condition may be spared unnecessary treatments.
A new genomic 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. 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 of all individuals when 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. 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.
Cancer is the result of genetic abnormalities that affect the function of particular genes. Genes determine the form, function, and growth patterns of cells. Those that accelerate or suppress growth are often involved in cancer. For example, many cancers have an abnormality in a gene that is responsible for stimulating cellular growth and/or the gene that normally prevents cancer is not working properly. Both of these genetic abnormalities can result in uncontrolled and excessive cellular growth, the hallmark trait of cancer. Genomic tests, or assays as they are called by scientists, are a tool for identifying the specific genes in a cancer that are abnormal or are not working properly. In essence, this is like identifying the genetic signature or fingerprint of a particular cancer.
Genomic testing is different from genetic testing. Genetic tests are typically used to determine whether a healthy individual has an inherited trait (gene) that predisposes them to developing cancer. Genomic tests evaluate the genes in a sample of diseased tissue from a patient who has already been diagnosed with cancer. In this way, genes that have mutated, or have developed abnormal functions, are identified in addition to those that may have been inherited.
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.