Abstract Book

ESTRO 37

S426

Results Between 2013 and 2016, 1,340 patients with PCa were treated, with median age and follow-up of 70 years and 14 months, respectively. From the total, 31 (2.3%) patients had symptomatic LRB confirmed by colonoscopy and classified according to RTOG as grade 1, 2 and 3 as follows: 13 (41.9%), 15 (48.4%) and 3 9.7%) patients, respectively. The interval between the end of RT to the beginning of LRB ranged from 2.4 to 54 months, with a median of 11 months. It was observed that 22 (71%) of the patients presented Gleason> 6; 23 (74.2%) PSA <10ng / ml; 20 (64.5%) T

Traditional and Western Medicine, Department of Radiation Oncology, Cangzhou, China

Purpose or Objective Prostate cancer is one of the most common cancers in the world, and the population of patients with intermediate- to high-risk localized prostate cancer (PCa) occupies a large proportion. The results of treatment after hypofractionated radiotherapy only have been reported from several small randomized trials. Therefore, we pooled the relevant data and conducted a meta-analysis to compare clinical outcomes of hypofractionated radiotherapy versus conventional radiotherapy in the treatment of intermediate- to high-risk localized PCa. Material and Methods Relevant studies were identified through searching PubMed, Embase and Web of Science databases till June, 2017. Hazard ratio (HR) or risk ratio (RR) with its corresponding 95% confidence interval (CI) was used as pooled statistics for all analyses. Results Six clinical cohorts were included with a total of 2827 intermediate- to high-risk localized PCa patients. The meta-analysis results showed that overall survival (HR=1.12, 95% CI: 0.93-1.35, p =0.219) and prostate cancer-specific survival (HR=1.29, 95% CI: 0.42-3.95, p =0.661) were similar in two groups. The pooled data showed that biochemical failure was RR=0.90, 95% CI: 0.76-1.07, p =0.248. The incidence of acute adverse gastrointestinal event (grade ≥ 2) was higher in the hypofractionated radiotherapy (RR=1.70, 95% CI: 1.12- 2.56, p =0.012); conversely, for late grade ≥ 2 gastrointestinal adverse event, a significant increase in the conventional radiotherapy (RR=0.75, 95% CI: 0.61- 0.91, p =0.003). Acute (RR=1.01, 95% CI: 0.89-1.15, p =0.894) and late (RR=0.98, 95% CI: 0.86-1.10, p =0.692) genitourinary adverse events (grade ≥ 2) were similar among the two groups. No publication bias was detected in this meta-analysis (all p ＞ 0.05). Conclusion Hypofractionated radiotherapy in intermediate- to high- risk localized prostate cancer was not superior to conventional radiotherapy and showed higher acute gastrointestinal adverse event in this meta-analysis. However, these findings should be utilized cautiously when directed in clinical treatment due to some limitations. PO-0817 Rectal bleeding and radiotherapy for prostate cancer. DVHs and potential clinical parameters A.C.A. Pellizzon 1 , M. Silva 1 , R. Fogaroli 1 , G. Godim 1 , M. Chen 1 , D. Guedes 1 , R.G.D.S. Rosa 1 1 AC CAMARGO CANCER CENTER, RADIATION ONCOLOGY, sao paulo, Brazil Purpose or Objective Rectal toxicity, in special late rectal bleeding (LRB), is a major concern for patients with prostate cancer (PCa) treated with radiotherapy (RxT). Although there is no single dose limit for the rectum recommended in the literature, the use of dose-volume histograms has been used as a reference to predict the probability of rectal toxicity, and to decrease its occurrence. Objective: to evaluate predictive factors associated with LRB in patients submitted to RxT for PCa. Material and Methods Methods: This is a uni-institutional retrospective analysis of patients treated with conformal (3D) and intensity modulated (IMRT) RxT, with doses ranging from 70 to 78 Gy. Clinical and dosimetric parameters (volume of the rectum receiving more than 40, 50, 60, 70 and 75 Gy) were correlated with the presence LRB.