Precision Medicine in Prostate Cancer: How Genetic Testing Makes a Difference

Back when scientists sequenced a human genome for the first time — a years-long project that took billions of dollars — they were in part motivated by the promise of a future where genetic information could be used to tailor medical treatment. Doctors know that patients respond differently to the same therapy, but if genetic data could be used to determine ahead of time which patients would do best on certain therapies, it could eliminate the trial-and-error process that is too often used in healthcare.

That’s the promise of precision medicine. Now, with millions of human genomes sequenced and databases full of valuable genetic information, we are regularly reaping the rewards of this investment.

Recently, scientists published results from a study showing that the Prolaris test from Myriad Genetics can be used to accurately identify which men with prostate cancer would benefit from more aggressive treatment, and which men can safely avoid it. This effort represents another step forward in precision medicine and offers a clearer path for clinical decision-making for this group of patients and their physicians.

The peer-reviewed study was published in the International Journal of Radiation Oncology, Biology, Physics — better known among researchers as the Red Journal — and was presented by lead author Dr. Jonathan Tward, senior author Dr. Todd Cohen, and their collaborators from a number of academic medical centers. In this project, the aim was to determine whether genetic testing could be used to prognosticate which men with prostate cancer would receive significant benefit from a type of hormone therapy known as androgen deprivation therapy (ADT).

Without genetic testing, men with prostate cancer have their risk of metastasis and other markers of cancer progression scored with a variety of clinical and pathological factors. In the new study, researchers evaluated genetic testing for 741 men with prostate cancer categorized as intermediate, high, or very high risk. The men had already been treated with radiation; some had received ADT in addition. Their outcomes were followed for an average of about six years. The original tumor samples from all men were assessed with the Prolaris genetic test, which scans key markers in a tumor to determine how aggressive the cancer is and which treatments to use.

The researchers found that adding Prolaris risk data significantly improved the ability to identify which men would benefit from hormone therapy and which men wouldn’t. For example, men with certain lower-risk Prolaris scores had a likelihood of just 3.7 percent that their cancer would metastasize in the next 10 years. That group of men can safely and confidently skip hormone therapy, avoiding the potential side effects of more aggressive treatment and saving unnecessary expense.

Looking at all the results generated from this study, the researchers concluded that incorporating genetic risk data from a tumor analysis made each patient’s risk score more accurate and custom-tailored compared to using the standard clinical and pathological factors alone.

From all of us at Myriad Genetics, congratulations to the researchers who undertook this impressive study! We’re thrilled to see that precision medicine is expanding to more and more patients all the time through advances in genetic testing.