Acute toxicity of robotic ultrahypofractionated radiotherapy Cyberknife™ in prostate cancer patients

Abstract

Our purpose was to evaluate the toxicity of CyberKnife™ based fractionated stereotactic radiotherapy (FSRT) in prostate cancer patients. One-hunred-thirty-two men with low (62) and intermediate (70) prostate cancer were enrolled in our prospective study. Mean age was 69. Total dose of 36,25 Gy in 5 fractions was prescribed. Image guided FSRT was performed on CyberKnife. Minimum follow-up ranged from 3 to 28 months. EORTC/RTOG scale was used to evaluate toxicity. A total of 47%, 10% and 2% of patients presented grade 1, 2 and 3 acute genitourinary toxicity, respectively. In 25% and 3% of patients, respectively, grade 1 and 2 acute gastrointestinal toxicity was observed. No significant association between acute grade ≥ 2 toxicity and clinical factors: age, androgen deprivation therapy or infections were found. Neither CTV nor PTV volumes had significant impact on acute grade ≥ 2 toxicity. Late toxicity was assessed in 104 patients. In 16% and 1% of patients late GU toxicity in grade 1 and 2, respectively, was presented. Late GI toxicity grade 1, 2 and 3 occurred in 8%, 3% and 1% of patients, respectively. The acute toxicity rates of fractionated stereotactic radiotherapy are low. Early data suggest also low late toxicity rates.