Clinical outcome of stereotactic body radiotherapy for localized prostate cancer: long-term results

Stereotactic body radiotherapy (sbrt) is an emerging treatmentoption which allows for extreme hypofractionation using moderntechnologies, because the low α/β-ratio favors the use of high dose perfraction in prostate cancer. there is a need for more data about sbrt. weprovide a long-term update of sbrt clinical outcome using cyberknife for thetreatment of localized prostate cancer. materials and methods: this studywas based on a retrospective analysis of 43 patients treated with sbrt usingcyberknife for localized prostate cancer (23.3% in low risk, 67.4% inintermediate risk and 9.3% in high risk). the target volume included theprostate with or without the seminal vesicles depending on the riskstratification and uncertainty margins that are kept at 3-5 mm. total dose of36.25 gy in 5 fractions of 7.25 gy were administered. results: 43 patientswith a median 73.6 months (range, 14 to 119 months) follow-up wereanalyzed. there was three biochemical failure (bcf). eight-year bcf freesurvival and overall survival were 92.0% and 73.1%, respectively. median psadecline rates were -0.301, -0.191 and -0.115 ng/ml/month, respectively, fordurations of 1, 2 and 3 years after radiotherapy and has remained plateau.median psa nadir was 0.27 ng/ml at median 38 months and psa bounce(median 0.33 ng/ml) occurred in 32.6% (n = 14) of patients at median 19months after sbrt. there was no grade 3 acute and late toxicity. conclusion:our long-term experience with sbrt using cyberknife for localized prostatecancer demonstrates favorable efficacy and toxicity