Toxicity and efficacy of three dose-fractionation regimens of intensity-modulated radiation therapy for localized prostate cancer

Outcomes of three protocols of intensity-modulated radiation therapy (imrt) for localized prostate cancer were evaluated. a total of 259 patients treated with 5-field imrt between 2005 and 2011 were analyzed. first,74 patients were treated with a daily fraction of 2.0 gy to a total of 74 gy (low risk) or 78 gy (intermediate or high risk). then,101 patients were treated with a 2.1-gy daily fraction to 73.5 or 77.7 gy. more recently,84 patients were treated with a 2.2-gy fraction to 72.6 or 74.8 gy. the median patient age was 70 years (range,54-82) and the follow-up period for living patients was 47 months (range,18-97). androgen deprivation therapy was given according to patient risk. the overall and biochemical failure-free survival rates were,respectively,96 and 82% at 6 years in the 2.0-gy group,99 and 96% at 4 years in the 2.1-gy group,and 99 and 96% at 2 years in the 2.2-gy group. the biochemical failure-free rate for high-risk patients in all groups was 89% at 4 years. incidences of grade ≥2 acute genitourinary toxicities were 9.5% in the 2.0-gy group,18% in the 2.1-gy group,and 15% in the 2.2-gy group (p = 0.29). cumulative incidences of grade ≥2 late gastrointestinal toxicity were 13% in the 2.0-gy group at 6 years,12% in the 2.1-gy group at 4 years,and 3.7% in the 2.2-gy group at 2 years (p = 0.23). so far,this stepwise shortening of treatment periods seems to be successful. © 2013 the author. published by oxford university press on behalf of the japan radiation research society and japanese society for radiation oncology.