ESTRO 36 Abstract Book

S717 ESTRO 36 _______________________________________________________________________________________________

Conclusion Preliminary findings show that our schedule of hypofractionated radiotherapy, delivered with FFF- VMAT and gated using beacon transponders, is a valid option for intermediate risk PC. Early results in terms of feasibility, toxicity profile and disease control are encouraging to warrant the pursuance of the study. EP-1338 High precision radiotherapy for early prostate cancer with concomitant boost to the dominant lesion. G. Riva 1 , G. Timon 1 , D. Ciardo 1 , A. Bazani 2 , D. Maestri 2 , D. De Lorenzo 3 , F. Pansini 2 , R. Cambria 2 , F. Cattani 2 , G. Marvaso 1 , D. Zerini 1 , D.P. Rojas 1 , S. Volpe 1 , F. Golino 1 , V. Scroffi 1 , C. Fodor 1 , G. Petralia 4 , O. De Cobelli 5 , R. Orecchia 6 , B.A. Jereczek-Fossa 7 1 Istituto Europeo di Oncologia - IEO, Radiotherapy, MIlan, Italy 2 Istituto Europeo di Oncologia - IEO, Medical Physics, MIlan, Italy 3 Istituto Europeo di Oncologia - IEO, Scientific Direction, MIlan, Italy 4 Istituto Europeo di Oncologia - IEO, Radiology, MIlan, Italy 5 Istituto Europeo di Oncologia - IEO, Urology, MIlan, Italy 6 Istituto Europeo di Oncologia - IEO, Medical Imaging and Radiation Sciences, MIlan, Italy 7 Istituto Europeo di Oncologia - IEO- Università degli Studi di Milano, Radiotherapy, MIlan, Italy Purpose or Objective To report preliminary results, in terms of acute toxicity, of an innovative hypofractionated treatment with concomitant boost to the dominant lesion for patients with early stage prostate cancer (PCa). Material and Methods This prospective phase II trial, supported by AIRC (Associazione Italiana per la Ricerca sul Cancro), started in June 2015. Patients with low- and intermediate-risk PCa who met the inclusion criteria underwent hypofractionated radiotherapy (RT) to the prostate with a total dose of 36.25 Gy in 5 fractions (biologically equivalent to a 90.6 Gy, considering a α/β ratio of 1.5 Gy) and a simultaneous integrated boost (SIB) to the dominant intraprostatic lesion (DIL) of 37.5 Gy in 5 fractions (biologically equivalent to a 96.4 Gy, considering a α/β ratio of 1.5 Gy). The DIL was identified by a multiparamentric magnetic resonance imaging (mpMRI) co-registered with planning CT. The treatment was delivered using a Varian Trilogy TM with RapidArc ® technology. Toxicity was assessed according to CTCAE v4.0 and RTOG/EORTC criteria. The preliminary evaluation of the first 13 patients was required to assess the feasibility of the treatment before completing the enrollment of 65 patients. Results The first 13 patients completed the treatment between June 2015 and February 2016. Patients’ characteristics are reported in Table 1. An example of dosimetric distribution is shown in Figure 1. With a median clinical follow-up of 5.9 months, ranging from 1 to 6 months, no grade 3 or 4 acute toxicity was reported. At the end of RT, only one patient experienced G2 gastrointestinal (GI) toxicity, and 4 patients had G1 genitourinary (GU) events. After one month, G1 GI toxicity was reported in 2 patients and G1 GU in 4 patients; no toxicity higher than G2 has been recorded. At 6 months from the end of treatment, 8 patients have been evaluated and no events higher than G2 have been experienced: 1 patient had G1 GI toxicity and 3 patients had G1 GU toxicity.

when planning treatment. Besides this, more patients need to be included in the study to identify a cut-off value that clearly reflects the association between grade ≥ 2 GUS toxicity and the trigone volume. EP-1337 High hypofractionation using beacon transponders in intermediate-risk prostate cancer: first results L. Di Brina 1 , G. D'agostino 1 , C. Franzese 1 , D. Franceschini 1 , T. Comito 1 , F. De Rose 1 , P. Navarria 1 , A. Tozzi 1 , C. Iftode 1 , A. Ascolese 1 , E. Clerici 1 , L. Pasini 2 , A. Benetti 2 , M. Scorsetti 1 1 Istituto Clinico Humanitas, Radiotherapy and Radiosurgery, Rozzano Milan, Italy 2 Istituto Clinico Humanitas, Urology, Rozzano Milan, Italy Purpose or Objective In the last decades, an improved diagnostic accuracy has led to an increased incidence of early stage prostate cancer(PC). For these patients a traditional course of radiotherapy(RT) remains a critical issue. Furthermore acceleration of RT could improve therapeutic ratio, especially in intermediate risk patients. Therefore we designed a study of hypo-fractionated stereotactic body radiation therapy(SBRT) delivered by Volumetric Modulated Arc Therapy(VMAT) with Flattening Filter Free(FFF) beams and gated using beacon transponders. We report our preliminary results on feasibility and early side effects. Material and Methods This is a prospective phase II study. Inclusion criteria were: age≤85 years, PS≤2, PSA≤20 ng/ml and Gleason Score (GS) 7 (NCCN intermediate class of risk), no distant metastases, no previous surgery other than transurethral resection of the prostate (TURP), no malignant tumors in the previous 5 years, IPSS≤ 7. Patients underwent pelvic MRI. Three beacons transponders were positioned transrectally within the prostate parenchyma by an urologist with an ultrasounds-guided procedure that was performed 7-10 days before simulation CT-scan. MR images were registered with those of simulation CT. The RT schedule was 38 Gy in 4 fractions delivered every other day with VMAT and 10MV FFF photons. Toxicity assessment was performed according to Common Terminology Criteria for Adverse Events (CTCAE) v4.0 scale. Results Between September, 2012 and May, 2016, 23 patients were recruited in the protocol and treated. Median follow-up (FUP) was 16 months (range: 7-27). Median age was 74 years (59-79), Median initial PSA (iPSA) was 7.0 ng/ml (range 3.12-12.7 ng/ml). All patients completed the treatment as scheduled, in a median 8 days (8-11). Median nadir-PSA after treatment was 0.78 ng/ml (range 0.2-4). Acute Toxicities were as follow: three patients (13%) presented G1 proctitis. Genito-urinary toxicity was observed in 57% of patients (n=13): in particular, 6 patients had G1 cystitis (26%) with 4 of these presenting even G1 increased urinary frequency (17%) ; G2 cystitis was observed in 7 patients (30%) with a G2 urinary frequency observed in two of these patients (9%); in only one patient a G2 urinary retention was observed and it was treated with transient catheterization and oral and rectal medications. No acute gastrointestinal ≥ G2 or genito- urinary ≥ G3 toxicity was found. No other toxicities were observed. At a median FUP of 16 months (range 7-27, from the time of diagnosis), only one patient presented an outfield relapse of disease, that was treated with androgen deprivation therapy (ADT). No other biochemical recurrence or progression of disease was observed.