Yueping Liu, Yexiong Li, Jin Jing

Beijing Cancer Hospital & Institute, Chinese Academy of MedicalSciences Dept. of Radiation Oncology

Objective：Toexplore the efficacy and toxicity of hypofractionated intensity-modulated radiotherapyof 45Gy in 9 consecutive fractions in the treatment of early stage prostate cancer.Method：From October 2011 to June2015, 21 patients with localized prostate cancer were enrolled in thisstudy. Themedian age of the patients was 72 years. According to NCCN recurrencerisk criteria,seven patients were at low risk group, 12 were at intermediate risk group, and 2were at high risk group. All patients were treated with hypofractionated intensity-modulatedradiotherapy of 45 Gy in 9 consecutive fractions to their prostate with or withoutseminal vesicle. Before radiotherapy, three gold fiducials were implanted into theprostate. In order to reduce the volume of high dose irradiation to rectum and bladder,aninflated rectal balloon was placed in the rectum at simulation and every treatmentand patients were treated with full bladder. Intensity-modulated radiotherapy (IMRT)was applied in 1 patient, Volumetric Modulated Arc Therapy (VMAT) in 17 patients,and tomotherapy in 3 patients. Image guided radiotherapy (IGRT) with gold fiducialregistration was adopted. Eighteen patients also received androgen deprivation therapy(ADT). The median time of ADT was 6 months. Result：Aftera median follow-up of 20 months (3~43 months), the prostate specific antigen (PSA)was reduced from 10.8±5.0ng/mlbefore radiotherapy to 0.5±0.4ng/mlat last follow-up. No patients developed biochemical failure. According to CommonToxicity Criteria (CTC 3.0), grade 1 acute gastrointestinal (GI) toxicity developedin 13 patients, grade 2 in 3 patients, grade 3 in 2 patients, grade 1 acute genitourinary(GU) toxicity developed in 16 patients， grade 2 in 4patients, and no grade 3 or higher toxicity occurred. Accordingto the Radiation Therapy Oncology Group (RTOG) late morbidity criteria, late (≥3months after radiotherapy) grade1 GI toxicity developed in 8 patients (38.1%), grade2 in 1 (4.7%), late grade1 GU toxicity occurred in 5 patients (23.8%), grade 2 in2 (9.5%), grade 3 in 1 (4.7%). No grade 3 or higher GI toxicity and grade 4 or higherGU toxicity developed. The potency was not evaluated for the limited follow-up time.Conclusion：Theresults of this shortened course hypofractionated IMRT regime for mainly low/intermediaterisk prostate cancer patients is favorable with low rates of severe late toxicity.It is worth further study.

Key Words：prostatecancer  hypofractionated intensity modulate