Genomic test helps guide decisions on RT after RP

A genomic tool for prostate cancer appears to provide physicians and patients with improved decision making about the use of radiation therapy after radical prostatectomy.

The Decipher genomic classifier (GenomeDx Biosciences, San Diego) was shown to predict biochemical failure and distant metastasis after radiation therapy, researchers from Thomas Jefferson University in Philadelphia reported in the International Journal of Radiation Oncology • Biology • Physics (2014; 89:1038-46).

“We are moving away from treating everyone the same. Genomic tools are letting us gauge which cancers are more aggressive and should be treated earlier with radiation, and which ones are unlikely to benefit from additional therapy,” said first author Robert Den, MD, who worked on the study with Adam Dicker, MD, PhD, Leonard Gomella, MD, and colleagues.

To better understand how to treat their patient population, the researchers assessed whether the Decipher test, which is designed to predict prostate cancer metastasis, could also predict which patients would most benefit from radiation treatment after surgery. The test generates a gene signature from a patient’s cancer tissue sample, and based on this signature, stratifies patients into high, intermediate, and low risk for cancer recurrence and metastases.

The researchers tested the genomes from tumor samples of 139 patients who had received radiation therapy following prostate surgery. Using medical records, they grouped the patients by the treatments they received after surgery and matched their records to the results of the genomic analysis.

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Results showed that the genomic analysis correctly predicted outcomes. Patients with a high Decipher score were more likely to develop metastases than those with a low score. In addition, those with a high Decipher score who received radiation earlier had longer survival than those who did not receive radiation immediately after surgery. The results showed the patients treated with radiation after surgery maintained low PSA levels for twice as long as those who were not treated with radiation.

Dr. Gomella pointed out that guidelines from the AUA and American Society for Radiation Oncology recommend an informed discussion in patients with adverse pathologic findings following radical prostatectomy concerning adjuvant radiation.

“While there are potential benefits, many patients may not need this additional treatment to prevent biochemical (PSA) recurrence or progression,” Dr. Gomella told Urology Times. “This type of genomic testing opens the door to more precise decision making for the use of early post-prostatectomy radiation.”

This study was supported by GenomeDx. Three study authors are employees of the company.