Dr Spratt on the Use of Radiation in Low– and High-Risk Prostate Cancer

Daniel Spratt, MD, Vincent K. Smith Chair, Department of Radiation Oncology, The University Hospitals, Seidman Cancer Center, professor, chair, Radiation Oncology, Case Western Reserve University School of Medicine, discusses the use of radiation therapy in patients with low- and high-risk prostate cancer.

Oncologists typically categorize localized prostate cancer into National Comprehensive Cancer Network risk groups ranging from low-risk to high-risk, Spratt begins. The phase 3 ProtecT trial (NCT02044172), with long-term follow-up, compared active monitoring, akin to a less intensive form of active surveillance vs surgery vs radiation therapy, he states. Although this trial predominantly enrolled low-risk patients, approximately one-third of patients were intermediate risk, Spratt expresses. Given the trial's time frame, many low-risk patients would likely now be classified as intermediate risk by contemporary standards, he adds. Nonetheless, based on this evidence, active surveillance is generally preferred over radical therapy for low-risk prostate cancer cases, Spratt says.

For intermediate-risk patients, recent data indicate comparable tumor control outcomes between surgery and radiation therapy, he continues. Studies such as the randomized phase 3 PACE-A trial (NCT01584258) comparing surgery with stereotactic body radiation therapy (SBRT)—a type of radiation therapy involving just five treatments—consistently show higher rates of urinary incontinence and erectile dysfunction with surgery vs SBRT, Spratt elucidates. However, with advancements in radiation therapy, including image guidance and the use of rectal spacer gels in other trials, there's no significant disparity in moderate or bothersome rectal toxicity between surgery and radiation, contrary to outcomes with older radiation techniques, he emphasizes.

Therefore, in intermediate-risk disease, hypofractionated radiation, such as SBRT requiring fewer treatments, is now favored, he expands. In high-risk prostate cancer, the sole local therapy that has level 1 evidence demonstrating improved survival over hormone therapy alone is radiation therapy, often combined with long-term hormone therapy, Spratt adds. Furthermore, data from the phase 2/3 STAMPEDE trial (NCT00268476) indicates a benefit with the addition of abiraterone (Zytiga) to androgen deprivation therapy for highly select high-risk patients, he concludes.