CyberKnife-based prostate cancer patient radioablation - early results of irradiation in 200 patients.

Prostrate cancer (PC) is one of the most common malignancies and is frequently treated with an 8-week course of radiotherapy. CyberKnife (CK) based radioablation enables completion of therapy within 5-9 days. The aim of this study is an evaluation of the effectiveness and tolerance of CyberKnife-based radioablation in prostate cancer patients.200 PC patients (94 low risk [LR], 106 intermediate risk [IR]) underwent CK irradiation every other day (fraction dose [fd] 7.25 Gy, total dose [TD] 36.25 Gy, time 9 days). PSA varied from 1.1 to 19.5 (median 7.7) and T stage from T1c to T2c. The percentage of patients with Androgen Deprivation Therapy (ADT), GI (gastrointestinal) and GU (genitourinary) toxicity (EORTC/RTOG scale), and PSA were checked at 1, 4 and 8 months, and thereafter every 6 months - up to a total of 26 months - post-treatment.The percentage of patients without ADT increased from 47.5% to 94.1% after 26 months. The maximum percentage of acute G3 adverse effects was 0.6% for GI, 1% for GU and G2 - 2.1% for GI and 8.5% for GU. No late G3 toxicity was observed. The maximum percentage of late G2 toxicity was 0.7% for GI and 3.4% for GU. Median PSA decreased from 7.7 to 0.1 ng/ml during FU. One patient relapsed and was treated with salvage brachytherapy.We conclude that CK-based radioablation in low and intermediate risk PC patients is an effective treatment modality enabling OTT reduction and presents a very low percentage of adverse effects.