ESTRO 36 Abstract Book

S292 ESTRO 36 2017 _______________________________________________________________________________________________

Conclusion Preliminary results of this trial demonstrate for both study arms the feasibility, tolerance, and acceptable toxicity profile of this treatment approach. Longer follow-up is needed to assess the impact of OTT and urethra-sparing on outcome, late toxicity, and QoL. PV-0553 Prognostic significance of Testosteron Level in prostate carcinoma patients treated with TAB and RT G. Ozyigit 1 , F. Akyol 1 1 Hacettepe University- Faculty of Medicine, Department of Radiation Oncology, Ankara, Turkey Purpose or Objective The aim of this study is to evaluate the prognostic significance of testosterone levels measured during total androgen blockade (TAB) in intermediate risk (IR) and high risk (HR) non-metastatic prostate adenocarcinoma patients treated with three dimensional conformal radiotherapy (3D-CRT) or intensity modulated radiation therapy (IMRT). Material and Methods The clinical data of 329 eligible T1-3N0M0 (AJCC 2010) prostate adenocarcinoma patients treated at our department between 1996-2011 with either 3D-CRT or IMRT were evaluated. The median age was 67 years. D'Amico 1998 risk classification was used, and 80 patients were in IR, as 249 patients were in HR group, respectively. The total 3D-CRT and IMRT dose was 70 Gy, 76 Gy respectively in 2 Gy daily fraction doses. All patients received TAB (combined LHRH agonist and bicalutamide), and 61% of patients were given less than 12 months of TAB. Total testosteron levels were measured in every 3 months during hormonal therapy. The castration level for testosteron was accepted as ≤20 ng/dL according to the European Association of Urology (EAU) criteria; and patients were categorized as castrated group (C) and non- castrated group (nC), accordingly. Log-rank test was used for univariate analyses (UVA), and Cox-regression model was used for multivariate analyses (MVA). Results Median follow-up was 9.2 years. There were no statistically significant differences between C and nC groups in terms of age, RT technique, TAB duration, risk group, Gleason score, PSA levels, T stage and RT dose. Five and 10 year overall survival (OS) rates were 97%, 91% for C group, and 90%, 75% for nC group (p<0.001). Five and 10 year biochemical relapse free survival rates (BRFS) were 87%, 83 % for C , and 71%, 51% for nC group (p<0.001). MVA revealed that testosteron level above 20 ng/dL (p=0.001) and Gleason score of 8-10 (p0.01) were found to be independent significant poor prognostic factors in predicting OS and BRFS. Conclusion The prognostic significance of testosteron levels was previously demonstrated in metastatic prostate cancer patients receiving hormonal therapy, but not for non- metastatic patients receiving TAB and radiotherapy . In a median follow-up of 9.2 years, we found that non-castrate levels of testosteron (>20 ng/dL) measured during TAB had significant detrimental effects both on overall and biochemical relapse free survival in intermediate-high risk non-metastatic prostate cancer patients. Thus, we recommend to continuously monitor testosteron levels during TAB in order to measure the efficacy of castration. PV-0554 Patient-reported outcomes from the phase III prostate HYPRO trial: urinary toxicity R.C. Wortel 1 , L. Incrocci 1 , F.J. Pos 2 , R.J. Smeenk 3 , A.D.G. Krol 4 , S. Aluwini 1 , M.G. Witte 2 , B.J.M. Heijmen 1 , W.D. Heemsbergen 2 1 Erasmus MC Cancer Institute, Radiation Oncology, Rotterdam, The Netherlands 2 Netherlands Cancer Institute, Radiation Oncology,

Amsterdam, The Netherlands 3 Radboud University Medical Center, Radiation Oncology, Nijmegen, The Netherlands 4 Leiden University Medical Center, Radiation Oncology, Leiden, The Netherlands Purpose or Objective In the Dutch phase III HYPRO trial (39x 2 Gy vs. 19x 3.4 Gy), the postulated non-inferiority of the hypofractionation arm with respect to the incidence of grade ≥2 late urinary toxicity was not shown. Moreover, a significant increase in grade ≥3 urinary toxicity was observed. In the current analysis we evaluated patient- reported urinary symptoms and possible relationships with hypofractionation and hospital of treatment. Material and Methods Patients with intermediate or high-risk prostate cancer from four hospitals applying image-guided IMRT protocols and recruiting >70 patients were analyzed, excluding patients with a baseline catheter. Long-term hormonal treatment (36 months) was prescribed to high-risk patients in hospital A-C but not in hospital D. A total of 561 patients (n=275 for standard fractionation (SF), hypofractionation (HF) n=296) with ≥1 follow-up symptom questionnaire were eligible (n=2355 total questionnaires). Treatment arm was balanced within hospitals. Local guidelines were applied for dose (in)homogeneity, margins (5-8 mm), and optimization. One hospital used MRI for prostate delineation (hospital A) and another hospital applied a rectal balloon (D). Hospital B and C varied in the applied safety margins of 5-6mm and 8mm, respectively. The study protocol did not provide dose constraints for the bladder; bladder delineation was done retrospectively. We calculated bladder and urethra dose (EQD2) with α/β ratios of 3 Gy and 5 Gy, and analyzed incidences of urinary symptoms between 6 months and 5 year. The impact of treatment arm and hospital on late urinary toxicity endpoints was calculated in a multivariate model including time and hormonal therapy. Results Dose to structures within the target volume (urethra, base of trigone area) was 78 Gy for SF vs 82.7 Gy for HF with α/β=3 Gy, and 78 Gy for both schedules with α/β=5. Average mean bladder dose was 29.2 Gy (SF) vs 29.9 Gy (HF) for α/β=3, (p=0.4), and 30.2 Gy vs 29.1 Gy (α/β=5, p=0.2), for SF vs. HF, respectively. Planned dose to the bladder varied significantly (p<0.05) between hospitals and was relatively low for hospital A and D (≈25 Gy vs. ≈33 Gy for hospital B and C, based on α/β=3 Gy). Symptoms of incontinence, straining, and weak stream were on average significantly more reported in the HF arm during follow- up ( FIG 1A-C ) and varied significantly between hospitals ( FIG 2A-C) . Hormonal treatment was not predictive in the current models. We established that baseline levels of urinary complaints were considerable as well ( FIG 1 ).