Intensity-modulated radiotherapy as primary treatment for prostate cancer: acute toxicity in 114 patients.

INTRODUCTION Dose escalation improves local control in prostate cancer. At Ghent University Hospital, intensity-modulated radiotherapy (IMRT) is used to increase the dose to the prostate and/or seminal vesicles. We report on acute toxicity in 114 patients who received IMRT for prostate cancer. METHODS AND MATERIALS Intensity-modulated radiotherapy was initiated after approval of our ethics committee. A class solution was used to plan all cases. Three beams (gantry 0 degrees , 116 degrees , and 244 degrees ) and anatomy-based segmentation were used to create an intensity-modulated dose distribution. Maximal rectal dose was set at 2 Gy per fraction. Detailed dose-volume histograms for all relevant structures were present. For all patients, we determined the pretreatment morbidity by a detailed preradiotherapy, in-house developed symptom scale. All patients were treated with 18 MV photons of an Elekta linear accelerator. Patients were seen on a weekly basis during treatment, and 1 month (M1) and 3 months (M3) thereafter. The registration of acute toxicity was standardized by a fixed questionnaire. The Radiation Therapy Oncology Group (RTOG) toxicity scale served as a basis, but additional symptoms, such as rectal blood loss, urgency, and incontinence, were scored as well. RESULTS All 114 IMRT plans were delivered successfully without any interruption or technical problem. Daily treatment time was always less than 8 min and less than 6 min in 90% of the cases. Grade 1 and Grade 2 gastrointestinal (GI) toxicities were observed in 44% and 29% of the patients, respectively, during the whole period. If only the RTOG scale was used, Grade 1 and Grade 2 GI toxicities were noted in 39% and 27% of the patients, respectively, leaving 34% free of acute RTOG-scaled toxicity. Grade 3 genitourinary (GU) toxicity was seen in 8 patients (7%), all but 1 during treatment. Grade 2 and Grade 1 GU toxicities were seen in 36% and 47% of the patients, respectively, leaving only 10% free of acute GU toxicity. DISCUSSION Anatomy-based IMRT to treat prostate cancer is incorporated into our daily routine without any problem. Acute toxicity is very low. Most of the recorded symptoms decrease over time, except for GI urgency and incontinence. The incorporation of additional symptoms makes the scoring more detailed.