Genetic Testing: A Game Changer for Prostate Cancer

Genetics is playing a bigger role in the detection and treatment of cancer. You’ve probably heard a lot about the BRCA1 and BRCA 2 genes. Women who inherit a harmful mutation of this gene have a much greater risk for breast and ovarian cancer. A simple blood or saliva test lets women know if they carry the mutation so they can make informed prevention and treatment decisions early, rather than later.

Genetic testing is also being used to guide the selection and boost the efficacy of cancer treatments. Long gone are the days of a one-size fits all treatment approach. As cancer cells continue to mutate, we now know they can create many variations—even within the same type of cancer. One man’s prostate cancer may not be exactly like another’s. Some prostate cancer is low-grade and slow-growing cancer that doesn’t spread, while another form of the disease can be high-grade cancer that is aggressive and very deadly. Knowing which type of prostate cancer you have is very important.

“Unfortunately, a PSA test and biopsy can’t conclusively distinguish between the two,” says Rich Bevan-Thomas, medical director of USMD Prostate Cancer Center. “That’s why more and more physicians are now taking a look at the genetic composition of their patients’ cancer cells. By doing so, we can gain a clearer picture of a man’s cancer and recommend the best treatment for destroying oncogenes.”

Oncogenes are abnormal genes that cause normal cells to develop into cancers. They also drive uncontrolled tumor growth. Prostate cancer researchers have been in hot pursuit of the oncogenes responsible for high-grade prostate cancer and have identified several. Today, many urologists and oncologist are using an oncogene test—Oncotype DX—to help determine how aggressive their patient’s prostate cancer may be. The test is designed to evaluate the personal genetic makeup of the patient’s cancer and determine his specific NCCN risk category.

“In many men diagnosed with prostate cancer, their cancer may initially look like a low-grade cancer, but then it turns out to be intermediate or even high-grade cancer,” says Dr. Bevan-Thomas. “We don’t want to be surprised. We want to know as soon as possible if a low-grade cancer has the potential to evolve into a deadly, high-grade cancer. We want to know before it spreads beyond the prostate.”

There are several companies that currently evaluate the genetic components of prostate cancer either at the biopsy stage or after the prostate has been removed (post prostatectomy). The Oncotype DX test evaluates the tissue collected during a biopsy using RNA analysis of 17 genes. RNA (ribonucleic acid) transfers the genetic code that is critical in the creation of proteins in healthy cells. It also protects DNA from being damaged.

“Analysis of RNA gives us insights into how the prostate cancer cells are likely to behave—not just now, but also in the future,” Dr. Bevan-Thomas says.

In addition to looking at RNA function, the oncotype test also evaluates four biological pathways known to facilitate the spread of aggressive prostate cancer. After completing both evaluations, the test yields a Genomic Prostate Score (GPS) ranging from 0 to 100. The score indicates how likely the cancer will remain low-grade.

“The lower the GPS score, the more likely a low-grade cancer is going to continue to behave like a low-grade cancer,” Dr. Bevan-Thomas says. “Perhaps the most important aspect of this genetic analysis is that it stratifies patients into the very low, low, or low-intermediate risk categories and let’s us know where they stand within that category. (See a sample report).

“Bottom line, we are able to look into the inner workings of cancer cells,” Dr. Bevan-Thomas says. “The Oncotype DX test gives us more information so, together, we can make better decisions based on the genetic makeup of an individual’s cancer. This is an exciting time for genetics and prostate cancer. I expect to see major strides in the next few years in this area—which will translate into more tools that will help physicians and patients make better-educated decisions about how to best treat a man's unique and individual cancer, rather than just follow a general recommendation.”

If you’ve been diagnosed with prostate cancer and would like to know more about genetic testing, please contact USMD Prostate Cancer Center online or at 1-888-PROSTATE (1-888-776-7828).

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