ESTRO 36 Abstract Book

S705 ESTRO 36 2017 _______________________________________________________________________________________________

-€ 473 [range: -€ 1,405-€ 528] (Figure 1).

predictors for prostate Cancer Specific Survival, Clinical Relapse Free Survival and Biochemical Relapse Free Survival. Conclusion In this, based on a large database, it was found that the Gleason score and the PSA measured at last low-up were significantly independent prognostic factors of survival for patients treated with postprostatectomy adjuvant RT. Acknowledgments: This work was supported by “5 per Mille 2009 Ministero Salute-FPRCOnlus”. EP-1329 IG-SBRT for localized prostate cancer: clinical results and late toxicity of a phase-II study A. Magli 1 , E. Moretti 2 , A. Tullio 3 , C. Foti 2 , M. Crespi 2 , M. Urpis 1 , A. Prisco 1 , M.R. Malisan 4 1 ASUIUD, Radiation Oncology, Udine, Italy 2 ASUIUD, Medical Physics, Udine, Italy 3 Hygiene and Clinical Epidemiology Institute - University of Udine, Department of Medical and Biological Sciences, Udine, Italy 4 ICTP, Master of Advanced Studies in Medical Physics, Trieste, Italy Purpose or Objective To evaluate the clinical outcome and late toxicity of a phase II study dealing with SBRT with a total dose of 42 Gy in 7 fractions, in patients with localized prostate cancer at low/intermediate risk (according to NCCN score) and at risk of pelvic lymph node involvement inferior to 17% as evaluated by the Roach formula. Material and Methods This study was based on a prospective analysis of 42 patients enrolled between May 2013 and November 2014. For planning, the GTV included the prostate with the 1/3 proximal seminal vesicles without margin; a margin of 5 mm in all directions around the GTV was applied to define the PTV. All patients were treated with IG-SBRT, utilizing VMAT technique with a 2 full arcs arrangement and photons with beam energy of 6 MV, according to pre- established treatment dose specifications and DHV constraints: in particular, for PTV, plans were optimised aiming to obtain V95%>95% D98%>94%, V2%<108%; concerning the rectum, the requirements were: mean<18Gy, V20<35%, V32 <10%, V37<5%,D1%<40Gy while for the bladder, the goal was to keep mean dose <14 Gy and V21 <40%, V33 < 30%, V38 <13%,D1%<40Gy. Routine institutional image-based patient position verification protocols foresaw daily on-line matching by CBCT. The acute and late toxicities were recorded using the RTOG/EORTC scale. Additional data were collected by means of I-PSS e IIEF-5 questionnaires. Biochemical failure was determined using the Phoenix definition. Results The median follow-up duration was 27 months (range: 24 to 36 months). The median age was 74 years (range: 57–80 years). Most dosimetric parameters for the OARs are well within the protocol constraints, with the n otable exception of maximal doses to rectum and bladder (exceeding in about 20% of cases), but we did not find any statistical correlation with late toxicities. Acute GU toxicity of grade 2 (increase in urinary frequency) was observed in 7% patients. The incidence rates of late GI and GU toxicity of any grade were 14.2% and 35.7%, respectively. The late GU toxicity of grade ≥ 2 was 4.7%. No GE late toxicity ≥ 2 was noted. Previous abdominal surgery appeared to be statistically significant (p= 0.004; Fisher’s test) for the increase of probability of late GE toxicity. The 3-year local recurrence-free survival rate was 98%, only one patient had clinical abdominal lymph node failure. Among the dosimetric data, only V21 (mean value: 22.1%; range: 8.5-55.2%) revealed to be statistically significant for the late GU (p= 0.035; Wilcoxon Mann Whitney Test). Conclusion

The virtual IRS had a 100% classification accuracy for this study, i.e. when the iNMB of the real IRS was negative, so was the iNMB of the virtual spacer, and visa- versa. Conclusion Individual patient assessment for implantation of an IRS will increase cost-effective ness of an IRS. The virtual IRS approach in combination with a toxicity prediction model and a cost-effectiveness analyses can serve as a decision support tool for the implantation of either a SPA or a RBI. EP-1328 Long term patients clinical outcome after adjuvant postprostatectomy Radiation Therapy P. Pietro Gabriele (Italy), A. Angelo Maggio, E. Elena Delmastro, E. Elisabetta Garibaldi, S. Sara Bresciani, M. Marco Gatti, A. Andrea Galla, M. Michele Stasi, D. Domenico Gabriele 1 IRCCS-FPO candiolo cancer center, radiotherapy, CANDIOLO Turin, Italy 2 IRCCS-FPO candiolo cancer center, medical physics, candiolo /urin, Italy 3 IRCCS-FPO candiolo cancer center, radiotherapy department, candiolo Turin, Italy 4 SASSARI university, radiotherapy department, SASSARI, Italy Purpose or Objective To study the outcome of patients (pts) treated for prostate cancer with postoperative radiotherapy (RT) after radical surgery Material and Methods From October 1999 and December 2015, 279 patients (age 42-77ys median 66) operated for prostate cancer were treated in our Institution with conformal radiotherapy (3D or IMRT). Median preoperative PSA was 9 (range: 0.5-104), median pathologic GS 7 (range: 4-10) and number of pts with ct1, cT2, cT3 and cT4 were 1, 60, 207 and 11, respectively. Lymph node invasion was presented in 34 patients; the number of nodes removed was 7 (0-38); the number of patients with positive margins were 195 (69 %); post-surgery PSA was 0.073 ng/mL (range: 0-6.22). Radiation therapy was performed with Linac from 1999 to 2009 by 3DCRT and with Tomotherapy from 2010 by IMRT- IGRT. Radiation dose were, 70.2 Gy (range 61.6-75.6 Gy) to the prostate bed and 46.8 Gy (45-50.4) to the pelvis, 1.8Gy per fraction. The pelvis was irradiated in 65 patients (24 %). 64 patients (23%) were treated during RT with hormone therapy and 49 (18%) followed the treatment after RT. Results With a median FU of 73.4 (range: 4-212) months from the end of RT the 10 years prostate Cancer Specific Survival was 88%; the Clinical Relapse Free Survival was 72% and Biochemical Relapse Free Survival 60%. Cox univariate and multivariate (MVA) analysis were performed. In MVA, the pathologic Gleason Score (p<0.0001; HR>1.49) and last follow-up PSA (p<0.001;HR>1.0006) were significantly