Cancer Investigation, 33:188–192, 2015 ISSN: 0735-7907 print / 1532-4192 online Copyright Copyright C  2015 Informa Healthcare USA, Inc. DOI: 10.3109/07357907.2015.1019679 ORIGINAL ARTICLE Cyberknife Treatment for Low and Intermediate Risk Prostate Cancer B. Detti, 1 P. Bonomo, 1 L. Masi, 2 R. Doro, 2 S. Cipressi, 2 C. Iermano, 2 I. Bonucci, 2 D. Franceschini, 1 V. Di Cataldo, 2 L. Di Brina, 1 M. Baki, 1 G. Simontacchi, 1 I. Meattini, 1 M. Carini, 3 S. Serni, 3 G. Nicita, 3 and L. Livi 1 1 Radiotherapy Unit, Azienda Ospedaliera Universitaria Careggi, University of Florence, Florence, Italy, 2 CyberKnife Center—I.F.C.A (Istituto Fiorentino di Cura ed Assistenza), University of Florence, Florence, Italy, 3 Urology Unit, Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy Cyberknife is an emerging treatment for early stage prostate cancer. Between October 2012 and January 2014, 32 patients were treated in our institution. Prescribed dose was 35–36.25 Gy in five fractions. Biochemical response was observed in 22 patients. Four patients experienced G2 acute genitourinary toxicity and in two cases we recorded G3 acute GU toxicity. 5 patients experienced G2 acute proctitis. At last follow up visit, all patients were still alive. 29 remained free of disease at last follow up appointment, while three developed a biochemical recurrence. Our experience confirms the efficacy and safety of Cyberknife for localized prostate cancer. Keywords: Radiation oncology, Prostate cancer, Cyberknife INTRODUCTION Prostate cancer (PC) affects 1 in 7 men at some point in their lifetime. In 2014, an estimated 233,000 men in the United States will be diagnosed with prostate cancer and 29,480 deaths from this disease are estimated (1). The management of low and intermediate risk PC involves surgery or radio- therapy (RT), due to the fact that results are comparable (2). However, there are many treatment options for patients treated with RT, ranging from fractionated external beam RT (with different fractionation schedules) to brachytherapy (high dose rate or low dose rate). None of them has shown superiority in terms of efficacy. Conventional RT as primary treatment for PC is usually protracted over 7–9 weeks, according to different protocols in different centers. This long treatment time affects patients’ quality of life and has a great impact on hospital resources. Hypofractionated RT can reduce overall treatment time. Apart from immediate advantages in terms of sparing time both for patients and for RT departments, this approach is Correspondence to: Davide Franceschini, MD, Radiotherapy Unit, Azienda Ospedaliera Universitaria Careggi, University of Florence, Largo G.A. Brambilla 3, Florence, Italy. Tel: +39 055 7947018, Fax: +39 0557947363. E-mail: davide.franceschini@unif.it Received 25 November 2014; accepted 08 February 2015. particularly promising in PC, due to radiobiological consid- erations. Indeed, PC cells have an estimated low α/β ratio, <3 Gy or less (3). Considering this low ratio and assuming an α/β ratio for early-responding tissues (like skin or mucosa) of 10 and for late-responding tissues (like bladder/rectal mu- cosa and muscle) of 3 (4, 5), hypofractonated RT should re- duce the normal tissue complication probability (NTCP) for bladder and bowel (5), compared to conventional schedules. From a practical point of view, this translates in an increase of the therapeutic index, allowing a dose escalation to the target with a good toxicity profile. Moving from these considerations, many moderately hy- pofractionated schedules for PC have been used in recent years in most RT facilities with promising results (6, 7). A new issue to be addressed is if a more pronounced hypofrac- tionation, i.e. RT in four or five fractions, can be at least as active, effective, and nontoxic as conventional or moderately hypofractionated regimens for patients with early-stage or- gan confined PC. In this study, we report our experience on 32 patients with early-stage organ confined PC treated with five fractions with CyberKnife Robotic Radiosurgery. MATHERIAL AND METHODS Between October 2012 and March 2014, 32 patients were treated with SBRT for early-stage organ confined PC. We considered patients with histological confirmation of prostate adenocarcinoma, Gleason score ≤3 + 4, Clinical and MRI stage T1c –T2c, PSA ≤20 ng/ml, prostate volume ≤100 cc. Exclusion criteria were prior pelvic radiotherapy, bilateral hip prostheses, or any other implants/hardware that would introduce substantial CT artifacts, and inflammatory bowel disease. Neoadjuvant and/or concomitant adjuvant hor- monal therapies were allowed according to physician’s decision. 