Acute toxicity of robotic ultrahypofractionated radiotherapy CyberKnifeTM in prostate cancer patients

Abstract

Our purpose was to evaluate the toxicity of CyberKnifeTM 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.