Image Guided Intensive Modulated Radiosurgery Boost Combined With Conformal Radiotherapy Prostate Cancer Patients

Radiobiological data shows that radiosurgery for Prostate Cancer (PC) Patients could be therapeutic option better then Conformal Radiotherapy (CRT). The aim of study is to evaluate acute toxicity of Image Guided Intensive Modulated Radiosurgery Boost (IGIMRS) combined with CRT in PC Patients. A total of 22 patients irradiated because of PC between August 2007 and October 2008. All patients were in low and intermediate risk group (T1c-T2b, pre-treatment PSA level less than 20 ng/ml, Gleason score less than 7). Nodal and distant metastases were excluded. Patients were irradiated using 20 MV photon beams. Prescribed doses were 7 Gy of IGIMRS, followed by 50 Gy/25 fractions of CRT and finally, the second 7 Gy of IGIMRS. Calculated equivalent doses for prostate were 78-84 Gy (depend on the α/β for prostate varying from 1.5 to 3 Gy). Calculated equivalent doses for rectum were 71,8-75,6 Gy (depend on the α/β for rectum varying from 4 to 7 Gy) in part of rectum obtaining 100% of prescribed dose. CTV was prostate. PTV for CRT was CTV + 7-15 mm of margin. PTV for IGIMRS was CTV + 3 mm of margin. During IGIMRS prostate position was evaluated using CBCT on Clinac 2300 linear accelerator. The RTOG/EORTC scale for evaluation of acute radiation effect were used. Follow-up ranged from 3 to 18 months (median 9.5). Three patients had acute rectal radiation effects score 1, only during treatment. 13 (59%) patients had no acute bladder radiation effects. We observed acute bladder effect score 1 in 8 patients and score 2 for only in 1 patient. Image Guided Intensive Modulated Radiosurgery Boost combined with Conformal Radiotherapy seems to be well tolerable and safe treatment modality of PC patients. We will start randomized study soon.