A University of Colorado Cancer Center study published ahead of print in the journal Brachytherapy shows that intermediate risk prostate cancer patients experience modest benefit from the addition of external beam radiation therapy (EBRT) to brachytherapy. The study is based on the results of 10,571 patients, of which 3,148 received brachytherapy plus EBRT and 7,423 received brachytherapy alone. Overall survival rates were 91.4 percent versus 90.2 percent at five-year follow up, and 85.7 percent versus 82.9 percent at seven-year follow up.
The study was led by first author Arya Amini, MD, resident in the Department of Radiation Oncology at the CU School of Medicine.
The modest gain in overall survival is set against concerns about possible effects of increased radiation exposure, cost and inconveniences of increased treatments. This makes the future clinical addition of EBRT to brachytherapy unclear. However, the trial also identified subsets of patients for whom combination therapy seems especially appropriate or inappropriate. For example, patients with health challenges in addition to prostate cancer, such as heart disease, lived no longer with combination therapy than with brachytherapy alone. In contrast, a population defined by the combination of Gleason score and level of prostate-specific antigen (PSA) seemed more likely to benefit from combination therapy.
In the United States, prostate cancer is diagnosed in nearly 200,000 men per year, resulting in approximately 30,000 deaths. In brachytherapy, a small “seed” of radioactive material is placed directly into the prostate. As the name implies, EBRT includes radiation directed at the prostate from outside the body.
An ongoing phase III clinical trial (RTOG 0232) seeks to further evaluate the usefulness of the combination of EBRT with brachytherapy, overall and in targeted patients.