Prostate Cancer Treated with Reduced-volume Intensity-modulated Radiation Therapy: Report on the 5-year Outcome of a Prospective Series

How to define a clinical target volume (CTV) as small as possible for prostate cancer to reduce the dose received by normal organs is an interesting study. We conduct a research to analyze the clinical efficacy of intensity modulated radiotherapy (IMRT) using reduced CTV in the treatment of prostate cancer. From January 2006 to June 2010, 78 patients with prostate cancer were treated with IMRT according to this institutional protocol. Of them, 18 had stage II tumors, 39 had stage III tumors, and 21 had stage IVa tumors. Clinical outcomes included overall survival, biochemical recurrence, recurrence-free survival, and acute and chronic injuries caused by radiotherapy. Risk factors were evaluated using the Cox regression model. As of December 31, 2014, all patients completed radiotherapy as planned. Myelosuppression was mostly grade 1, acute urinary injury was mostly grades 1 and 2, and intestinal injury was mostly grade 1. The 5-year follow-up rate was 91.0%. The overall, progression-free, biochemical recurrence-free, and distant metastasis-free survival rates were 82.1%, 79.4%, 84.6%, and 94.9%, respectively. Tumor volumes defined by small target volumes and Radiation Therapy Oncology Group were 274.21 ± 92.64 and 600.68 ± 113.72, respectively, representing a significant difference (P < .05). Age, prostate-specific antigen level, eastern cooperative oncology Group score, Gleason score, and volume of CTV were independent risk factors for mortality and disease progression. Our findings indicated that IMRT with reduced CTV have less acute and chronic injuries caused by radiation, particularly grade 3 or higher urinary and intestinal injuries, while ensuring survival benefits and protecting the hematopoietic function.