New genomic test can direct appropriate use of radiation therapy following prostate surgery

17
Feb

Dr. Robert Den

Dr. Robert Den

The identification of the right patients for post-operative radiation therapy and the timing of administering that therapy are not easily answered by clinical risk factors alone. The study, published in the Journal of Clinical Oncology, showed that patients with low genomic risk may be optimally managed with observation after radical prostatectomy (prostate surgery), while those with high genomic risk may be better managed earlier with adjuvant radiotherapy. The study, conducted by researchers from Thomas Jefferson University and Mayo Clinic using a commercially available genomic classifier by GenomeDx.

“The optimal timing of post-prostatectomy radiation therapy is a subject of debate,” says Robert Den, M.D., of the Sidney Kimmel Medical College of Thomas Jefferson University and lead author of the study. “Common practice is to wait for prostate-specific antigen (PSA) rise after surgery before intervening with radiation treatment. The results of this study suggest that we can use a genomic test to identify a group of men who will benefit from earlier administration of additional local treatment.”

Current clinical practice guidelines from the American Urological Association (AUA) and the American Society for Radiation Oncology (ASTRO) recommend physicians offer adjuvant radiotherapy after surgery for men who have been diagnosed with intermediate and high-risk prostate cancer. These recommendations are based on evidence from multiple randomized clinical trials, which demonstrated the efficacy of earlier, or adjuvant radiotherapy with reductions in recurrence and progression as compared to a “wait-and-see” approach after surgery. However, not all men receive a benefit from early radiation therapy, and there is an obvious need to identify patients who will and won’t benefit, so as to avoid overtreatment and serious side effects such as incontinence, impotence, and rectal bleeding.

According to the AUA, adjuvant radiation therapy is administered because of adverse pathology after radical prostatectomy, while salvage radiation therapy refers to initiation of radiation therapy only after PSA rise, commonly referred to as biochemical recurrence. Until now, clinicians have used pathology and clinical risk factors, which are less accurate measures of metastatic risk, to select men appropriate for treatment with radiation therapy.

“This potentially practice changing study is an example of the collaborative nature of the multidisciplinary genitourinary group at the Sidney Kimmel Cancer Center at Thomas Jefferson University which provides the highest quality of care to our patients,” says Dr. Leonard Gomella, the Bernard W. Godwin Professor of Prostate Cancer and Chairman of Department of Urology.

“Determining the right patient and the right time for radiation therapy is not straightforward. Patients have to balance the potential complications from radiation treatment with the risk of prostate cancer recurring. This test may enhance our ability in deciding who should or should not be considered for adjuvant radiation versus close monitoring,” says R. Jeffrey Karnes, M.D., associate professor and vice chair in Urology at Mayo Clinic and an investigator on the study.

The study, entitled, “A Genomic Classifier Identifies Men with Adverse Pathology after Radical Prostatectomy Who Benefit from Adjuvant Radiation Therapy,” included 188 prostate cancer patients who received radiation therapy after prostate surgery at Thomas Jefferson University and Mayo Clinic between 1990 and 2009. The genomic classifier stratified patients with low, average, and high genomic risk with 0%, 9%, and 29% five-year cumulative incidence of metastasis (p=0.002). Patients with average-to-high genomic risk who were treated with the more aggressive adjuvant radiation therapy had a five-year metastasis incidence of only 6% compared to 23% (p=0.008) for those who waited for PSA recurrence to trigger initiation of salvage therapy. In addition, the study found no disadvantage for salvage therapy in men with low genomic risk, suggesting that these men may improve quality of life by waiting for possible PSA rise rather than taking a course of immediate radiation therapy after radical surgery.

The researchers included Drs. Adam Dicker, Leonard Gomella, Edouard Trabulsi, and Costas Lallas.

The abstract is available at PubMed and the full publication is available at the Journal of Clinical Oncology.

Discussions of the publication can be found at the UrologyTimes.com and OncologyPractice.com and the GenomeDX Press Release and at the ASCO Post and The “New” Prostate Cancer InfoLink.

Media Only Contact:
Edyta Zielinska
Thomas Jefferson University Hospital
Phone: (215) 955-6300
Published: 2/17/2015