Prostate Caner - Genomics & Oncotype DX
by Dr. C.H. Weaver M.D. updated 5/2019
The Oncotype DX® Genomic Prostate Cancer Test—measures the aggressiveness of prostate cancer and may help men choose between immediate treatment or active surveillance and avoid unnecessary treatment.
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.
Genomic testing can help doctors to:
- Determine a patient’s prognosis (potential outcome)
- Determine whether a cancer is aggressive/fast growing or slow growing
- Choose the most effective treatment for each individual cancer
- Monitor patients who are undergoing treatment to determine if the treatment is working
Monitor patients who are in remission to catch a potential disease progression early when it is more treatable.
Oncotype DX GPS in Early Stage Prostate Cancer
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.
Oncotype DX GPS strongly predicts 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.1
More than fifty percent of men diagnosed with prostate cancer have low-risk disease with less than a three percent chance of developing advanced, life-threatening disease. However, the large majority currently receive immediate invasive treatment because conventional clinical and pathological evaluations of their needle biopsies do not adequately predict whether aggressive cancer is present in the prostate at time of diagnosis.
Large Independent Validation Study Validates Oncotype DX Prostate Cancer Test.
An independent clinical validation study conducted by the Center for Prostate Disease Research (CPDR) demonstrating that the Oncotype DX® GPS predicts multiple clinical endpoints related to disease aggressiveness in men with low- and intermediate-risk prostate cancer. This study validated the Oncotype DX prostate cancer test as a predictor of biochemical recurrence, a rise in prostate-specific antigen (PSA) following surgery, which is a measure of longer-term outcomes for aggressive disease. It also reconfirmed the test’s ability to predict adverse pathology from the biopsy, as previously demonstrated in a published validation study performed by the University of California, San Francisco (UCSF).
Results from the latest clinical validation study, published in European Urology this month online*,* show that the Oncotype DX test predicts near- and longer-term outcomes in a racially diverse group of men with clinically localized prostate cancer. The analyses, conducted in collaboration with the Uniformed Services University of the Health Sciences’ Center for Prostate Disease Research (CPDR), reconfirmed the biopsy-based Oncotype DX prostate cancer test as a predictor of whether adverse pathology would be found if the prostate were removed by surgery. Additionally, for the first time, the Oncotype DX prostate cancer test was validated as a strong independent predictor of biochemical recurrence, which is a rise in PSA following surgery. Furthermore, the study, in which 20 percent of patients were African-American men, demonstrated that Oncotype DX is similarly predictive of outcomes in both Caucasian and African-American men.
 Hornberger J, Chien R. Meta-analysis of the decision impact of the 21-gene breast cancer Recurrence Score in clinical practice. Presented at the 33rd annual San Antonio Breast Cancer Symposium, December 8-12, 2010. Abstract P2-09-06.
 Tang G, Costantino JP, Crager M, Shak S, Wolmark N. Comparing the prediction of chemotherapy benefit in patients with node-negative, ER-positive breast cancer using the Recurrence Score and a new measure that integrates clinical and pathologic factors with the Recurrence Score. Presented at the 33rdannual San Antonio Breast Cancer Symposium, December 8-12, 2010. Abstract S4-9.
1 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.