From 2008 to 2014, 36 patients newly diagnosed, low- and intermediate-risk (NCCN definition) prostate cancer were treated with SBRT using Cyberknife. Total dose of 36.25 Gy in 5 fractions of 7.25 Gy were administered. No one received androgen deprivation therapy (ADT). PSA nadir and rate of change in PSA (slope) were calculated and compared.
With a median follow-up of 52 months (range, 13–71), the median rates of decline of PSA were −0.359, −0.199 and −0.127 ng/mL/month, respectively, for durations of 1, 2 and 3 years after radiotherapy, respectively. The decline of PSA was maximal in the first year and continuously decreased for durations of 2 and 3 year. The median PSA nadir was 0.27 ng/mL after a median 33 months. 5-year biochemical failure (BCF)-free survival was 100% for low- and intermediate-risk patients.
In this report of low- and intermediate-risk prostate cancer, continuous decrease of PSA level for duration 1, 2 and 3 year following SBRT using Cyberknife resulted in lower PSA nadir. Also, SBRT leaded to long-term favorable BCF-free survival in low- and intermediate-risk prostate cancer.