Abstract: Objective To investigate the longterm outcome and safety of prostate cancer patients treated with intensitymodulated radiotherapy（IMRT） reduced clinical target volume（CTV）. Methods From Jan. 2006 to Jun. 2010，78 patients with prostate cancer were treated with IMRT. Total dose was 72.6 Gy，2.2 Gy per fraction， 33 fractions. The indexes of clinical observation including acute and chronic injury, overall survival（OS）， freedom from biochemical（FFB）， progressionfree survival（PFS）， distant metastasisfree survival（DMFS）. Cox regression model was used to evaluate the risk factors predicting the prognosis. Results The volume of tumor according our protocol and RTOG were （274.21±92.64） cm3 and （600.68±113.72） cm³， separately, and the differences were statistically significant（P＜005）. All patients were completed on schedule radiotherapy， bone marrow suppression was in grade 1， acute urinary injury was mostly in grade1-2， and the intestinal damage priority was in grade 1. By December 31, 2014， the 5 -years follow-up rate was 91.0％. The 5-year survival rate, 5year progressionfree survival rate, 5year freedom from biochemical rate and distant metastasis-free survival rate were 82.1％，79.4％，84.6％ and 94.9％, respectively. Cox's proportional hazards regression model showed age，PSA，ECOG score and Gleason score were the independent risk factors of OS and PFS.
Conclusion The reduced CTV can gain comfortable survival benefit， and it can reduce acute and chronic injury， meanwhile， it can protect hematopoietic function of patients.