By: Eric Klein, MD
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Overtreatment of prostate cancer represents one of the most significant issues in men’s health today. As a result of the limited information available from a biopsy, more than 90 percent of low-risk patients undergo immediate treatment, such as prostate removal or radiation, despite having less than a 3 percent chance of their low-risk disease progressing to become deadly.
An advanced genetic-based test, called the Oncotype DX Prostate, can help your doctor more accurately determine just how aggressive your cancer is – and whether surgery or radiation therapy is truly necessary.
Test recommended for Medicare coverage
In recent news, Palmetto GBA, a Medicare Administrative Contractor that assesses molecular diagnostic technologies, is recommending coverage of the Oncotype DX prostate cancer test for qualified Medicare patients throughout the United States. It has not taken effect, as this proposal will go through Medicare’s review process. This includes a public comment period, finalization and notification.
The goal of the proposal is to help determine which patients with early-stage prostate cancer can be conservatively managed rather than treated with definitive surgery or radiation therapy.
For slow-growing, low-risk prostate cancers, active surveillance may be a better option. This means that cancer is monitored with periodic clinic visits and prostate-specific antigen (PSA) tests — and repeat biopsies every year or two. The test helps identify more men who can opt for active surveillance. It also can identify men whose cancer is actually more aggressive than doctors originally thought.
What the test measures
The Oncotype DX prostate cancer test measures the level of expression of 17 genes across four biological pathways to predict a man’s prostate cancer aggressiveness.
The test results, which are individual to each person based on his genetic information, create a Genomic Prostate Score (GPS) that ranges from 0 to 100. This score is combined with other factors to help doctors further determine prostate cancer risk before starting treatment.
By adding the individualized biological information, more men with low-risk disease can confidently choose active surveillance and be spared unnecessary treatment and possible life-altering side effects, such as incontinence and impotence.
How the test was developed
To develop the new test, researchers in Cleveland Clinic’s Glickman Urologic and Kidney Institute conducted studies evaluating 700 patients at Cleveland Clinic with manufacturer Genomic Health. Working together with pathologists, Cristian Magi-Galluzzi MD and Sarah Falzarano MD, they worked to identify genes important in both low-grade and high-grade tumors.
In doing this, they tackled key challenges in assessing prostate cancer risk, including the problem of tumors being too varied to fully interpret their risk from one patient to another. With the test, doctors can improve risk assessment when they diagnose a patient and can choose the most appropriate treatment options.
They were able to measure and analyze gene expression in prostate cancer tissue samples from both radical prostatectomy (prostate removal) and very small needle biopsy specimens. In the final analysis, they found that the expression of 17 genes could be converted to a reproducible GPS to accurately predict disease aggressiveness of the entire prostate before considering treatment options.
Study to validate the findings
Researchers at the University of California at San Francisco validated the findings in another study of 395 patients, adding the biological information revealed by the GPS. They significantly increased the number of patients identified as having very low risk disease, making them appropriate for active surveillance from 5-10 percent to 26 percent.
Specifically, more than one-third of patients originally classified as low-risk based on clinical measures were identified by GPS as very low-risk and could confidently choose active surveillance.
Also, patients who needed more aggressive treatment were identified. About 10 percent of patients originally classified as very low or low-risk by clinical factors were identified by the test as having more aggressive disease, which would more appropriately be considered for immediate treatment.
The results have also been validate din another study performed at the Center for Prostatic Diseases in Washington, DC.
The test must be ordered by a physician, who will then get a report of the GPS, and can meet with you to share the results, discuss the implications, and help you decide on the best options for you.