ESTRO 2020 Abstract book

S673 ESTRO 2020

being observed (GG 1: 3 cases, GG 2: 2 cases, GG 3: 3 cases). Five-year local control (LC) was 94.9%, 5-year distant metastases-free survival (DMFS) was 95.1%. Cox regression analysis showed a direct correlation between WHO 2016 Grade Group and survival. In particular the hazard ratio (HR) for BRFS was 3.68 (95% C.I. 1.48- 9.12, p=0.004); HR for LC was 2.90 (95% C.I. 1.01-8.44, p=0.04); HR for DMFS was 4.52 (95% C.I. 1.29-15.79, p=0.01) Conclusion This 5-year follow-up analysis confirms that SBRT is a valid therapeutic approach for low- and intermediate risk prostate cancer patients, warranting an adequate control of disease, with mild toxicity profiles. It also confirms the significantly different prognosis, within the intermediate- risk disease, between patients with GG2 and GG3 disease. PO-1190 The 100 most cited articles in prostate cancer brachytherapy: A bibliometric study H. Zhao 1 , G. Cheng 1 , N. Wu 1 , M. He 1 , Z. Zhao 1 , N. Zhang 1 1 China-Japan Union Hospital of Jilin University, Radiation Oncology, Changchun, China Purpose or Objective Bibliometric analysis provides an objective means to describe the impact of various articles. The aim of this study was to identify the 100 most-cited research articles in prostate cancer brachytherapy (PCB) and to review characteristics of these citation classics. Material and Methods The Institute for Scientific Information (ISI) Web of Science was used to identify the 100 most cited articles in PCB as of 16 September 2019. We searched MeSH terms “Prostatic Neoplasms” and “brachytherapy” or their all Entry terms in the title, respectively, and then takes the intersection. We then reviewed the 100 most cited articles and analysis the networks visualization using VOSviewer software. Results We searched 2,489 articles to find the 100 most cited articles in PCB. The 100 most cited articles in PCB were published between 1995 and 2017, and the citations ranged from 454 to 59, which collectively had been cited 10,543 times at the time of searching. The most cited PCB article was “American Brachytherapy Society (ABS) recommendations for transperineal permanent brachytherapy of prostate cancer” at 454 citations. Besides, three recommendations from AAPM, GEC/ESTRO- EAU and GEC/ESTRO were also received high citations (150, 135 and 120; ranked 16, 22 and 26). These articles were from 11 countries, with most publications being from the United States (n=64), followed by Canada (n=8) and England (n=8), Germany (n=5), Spain (n=4) and Australia (n=3). The International Journal of Radiation Oncology, Biology, Physics produced the most articles (n=48), followed by Journal of Urology (n=11), Radiotherapy and Oncology (n=9), Cancer (n=6) and Urology (n=6). 480 co- authors contributed to the 100 most cited articles and total 2078 links between co-authors (see Figure 1). Martinez, AA has the most articles (n=10), followed by Blasko, JC (n=9), Grimm, PD (n=8), Gustafson, GS (n=6), Potters, I (n=6) and Sylvester, JE (n=6). The permanent interstitial brachytherapy (n=53) was the most widely used treatment modality, followed by the temporary brachytherapy (n=38). Quality of life (n=33) was the most topics, followed by long term outcomes (n=19). The network visualization of keywords from the 100 most cited articles according to the average published year is shown in Figure 2.

very high 239 (13%), and N+ 210 (11%). Intensity-modulated RT (IMRT) was done in 74%, and hypofractionation (HF) or ultra-HF were selected in 47% and 9%, respectively. The irradiated dose was median biologically effective dose (BED) 179.1 (range, 97.7-225.0) Gy 1.5 . With a median follow-up of 73 months, the 5- and 10-year BCFFS rates were 81% and 58%, and OS rates were 95% and 83%, respectively. Significantly differentiated prognosis was shown as NCCN risk groups. (5-yr BCFFS: 92%, 84%, 81%, 76%, and N+ 63%, p<0.001; BCF rate: 8%, 15%, 21%, 26%, and N+ 38%, p<0.001). In the univariate analysis for BCFFS, stage, Gleason score, RT modality, dose, and fractionation scheme were significant factors. There was a significant linear relationship between BED and BCFFS (p=0.032), with 179 Gy 1.5 (EQD2 77 Gy) being the most significant cut-off. In the multivariate analysis, ADT, IMRT, and ≥179 Gy 1.5 were still associated with better BCFFS (all Ps<0.05). Although there was no significant factor in low-risk group, slightly higher dose (≥170 Gy 1.5 ) and HF were significant factors in intermediate-risk group (p=0.02, 0.034). In high- risk group, ADT and ≥179 Gy 1.5 were independently significant factors (p<0.001, 0.009). The rate of toxicity (≥grade II) was acceptable (acute GU 11%, acute GI 7%, late GU 13%, late GI 7%, urinary incontinence 7%, impotence 5%), although acute GI and late GU toxicity could be increased with whole pelvis RT (all Ps<0.001). Conclusion Based on a large multi-institutional cohort of Korea, EBRT was an effective and noninvasive treatment option for non-metastatic prostate cancer and the most recent NCCN risk classification proved to be a useful predicting tool. In the era of patient stratification, differentiated RT dose in each risk group (higher dose in high risk group) should be selected. Modern RT techniques (HF, IMRT) will effectively deliver higher doses without increasing severe toxicities. PO-1189 VMAT SBRT for localized prostate cancer: 5- year update on toxicity and survival G.R. D'Agostino 1 , L. Di Brina 1 , C. Franzese 1 , C. Iftode 1 , P. Mancosu 1 , F. De Rose 1 , E. Clerici 1 , G. Reggiori 1 , M. Badalamenti 1 , M. Scorsetti 1 1 Humanitas Research Hospital, Radiotherapy and Radiosurgery, Rozzano Milan, Italy Purpose or Objective This study updates our previously reported experience on the safety and efficacy of a Linac-based stereotactic body radiotherapy (SBRT) in patients with low or intermediate risk prostate cancer. Material and Methods Biopsy confirmed prostate cancer patients were enrolled, provided that they had the following characteristics: initial PSA <20ng/ml, Gleason Score <8, IPSS <8. The treatment schedule was 35 Gy in 5 fractions, delivered every other day, with volumetric modulated arc therapy and flattening filter free beams. Toxicity was recorded according to CTC-AE criteria v3.0. Biochemical failure was calculated according to the Phoenix criteria. Results Between February 2011 and March 2015, 90 patients were enrolled (53 low risk, 37 intermediate risk, according to the NCCN criteria). The median age was 71 years (range 48–82). The median initial PSA was 6.98 ng/ml (mean 7.18, range 2.7–17.0). According to the ISUP - WHO 2016 Grading System 53 patients (58.9%) had a Grade Group (GG) 1, 24 patients (26.7%) a GG 2 and 13 patients (14.4%) a GG 3 prostate cancer. Acute toxicity was mild, and already reported. Urinary late toxicity, represented by urgency and/or dysuria, was G1 in 45 patients (50.0%), G2 in 3 patients (3.3%). A G1 late proctitis was recorded in 17 patients (18.9 %). One patient (1.1%) experienced a G2 rectal hemorrhage. At a median follow up of 75 months (range 13-109) all patient are still alive. Overall 5-year biochemical relapse- free survival (BRFS) was 92.5%, 8 biochemical relapses