Preliminary results show that a shortened course of radiation therapy for prostate cancer, stereotactic body radiation therapy (SBRT), provides good PSA response for early stage cancer and has the same side effects as other treatments, according to a March 15 study in the International Journal of Radiation Oncology*Biology*Physics.
In the study, researchers from Stanford University in Stanford, Calif., treated 41 men with low-risk prostate cancer with image-guided SBRT alone using the CyberKnife from Accuray.
The median follow-up was 33 months. There were no RTOG Grade 4 acute or late rectal/urinary complications. There were two patients with RTOG Grade 3 late urinary toxicity and none with RTOG Grade 3 rectal complications. The investigators observed a reduced rate of severe rectal toxicities with every-other-day versus five consecutive days treatment regimen. A benign PSA bounce was observed in 12 patients occurring at 18 months after treatment.
At last follow-up, they reported that no patient has had a PSA failure regardless of biochemical failure definition. Of 32 patients with 12 months minimum follow-up, 25 patients achieved a PSA nadir greater than or equal to 0.4 ng/mL. A PSA decline to progressively lower nadirs up to three years after treatment was observed.
"The early and late toxicity profile and PSA response for prostate SBRT are highly encouraging. Continued accrual and follow-up will be necessary to confirm durable biochemical control rates and low toxicity profiles," according to Christopher King, PhD, MD, an associate professor of radiation oncology at Stanford University School of Medicine in Stanford, Calif., and colleagues.
However, the authors cautioned that further follow-up will be necessary to establish its efficacy for long-term treatment.