ESTRO 36 Abstract Book

S960 ESTRO 36 2017 _______________________________________________________________________________________________

Japan 2 Iwate Medical University, Urology, Morioka, Japan

adding additional clinical studies, not necessary of brachytherapy as monotherapy. Those limitations are: the fit is over conditioned by the only fraction datum, the data are heterogeneous, and its external validity may be limited, we do not properly know the associated uncertainties nor the dose distributions. References [1] Prada PJ et al. Radiother Oncol 2016;119:411-6. EP-1769 Hypofractionated EBRT and single fraction HDR brachytherapy for patients with prostate cancer. D.E. Kazberuk 1 , T.M. Filipowski 2 , A. Szmigiel-Trzcińska 3 , M. Niksa 3 , D. Hempel 4 , J. Topczewska-Bruns 2 , W. Nowik 5 , B. Pancewicz-Janczuk 6 1 Bialystok Comprehensive Cancer Center, Brachytherapy, Bialystok, Poland 2 Bialystok Comprehensive Cancer Centre, Radiotherapy, Bialystok, Poland 3 Bialystok Comprehensive Cancer Centre, Brachytherapy, Bialystok, Poland 4 Bialystok Comprehensive Cancer Center, Radiotherapy, Bialystok, Poland 5 Bialystok Comprehensive Cancer Centre, Physics, Białystok, Poland 6 Bialystok Comprehensive Cancer Centre, Physics, Bialystok, Poland Purpose or Objective To evaluate the short term efficacy, early toxicity and dosimetric aspects of combined HDR-BT with EBRT in the radical treatment of prostate cancer patients (PCPs). Material and Methods 40 PCPs underwent combined treatment including hypofractionated EBRT (37.5 Gy in 15 fractions over 3 weeks) and conformal HDR-BT between September 2013 and May 2015. The mean age was 69 years with average PSA 6,7 ng/ml and median Gleason score 6,8. T stage was distributed from T1 to T2c. Half of the patients received androgen deprivation. Treatment was delivered using IMRT with an 6- or 15-MV linear accelerator. HDR brachytherapy catheter insertion was performed under spinal anaesthesia. The median number of catheters was 17 (14-18). HDR brachytherapy was delivered using an Iridum-192 source (Nucletron) and treatment planning system: SWIFT 2.11.8 and Oncentra Prostate 3.0.9./4.0. Dose volume constraints included: prostate V 100 ≥95 %, V150 and V200 below 40%; maximal urethral dose ≤ 120% and average rectal dose ≤ 85% of the prescription dose. Patients were monitored weekly during radiotherapy and in 3 months intervals after treatment. Follow-up visit included clinical examination and PSA value assessment. The acute toxicities were graded according to the EORTC/RTOG scales. Results The median V100 was 93% and median D90 was 103%. All patients finished the scheduled therapy without interruption. The most common urinary symptoms were: urgency, frequency, dysuria and nocturia. The rectal symptoms (urgency, frequency) were rare. No grade 3 and 4 acute toxicities were recorded. No patient developed clinical or biochemical progression. The constant decrease of PSA level was observed during follow up. Conclusion Single fraction 15 Gy HDR-BT with hypofractionated EBRT enables dose escalation with excellent dosimetric parameters for the radical treatment of PCPs. The treatment was well tolerated by all patients with satisfactory disease control in the short and medium term. EP-1770 Unpredictable PSA failure in intermediate-risk prostate cancer after seed implant brachytherapy K. Kikuchi 1 , R. Nakamura 1 , H. Kakuhara 1 , S. Yamaguchi 1 , H. Oikawa 1 , W. Obara 2 , H. Ariga 1 1 Iwate Medical University, Radiation Oncology, Morioka,

Purpose or Objective The role of seed implant brachytherapy (BT) in radiotherapy for organ-confined prostate cancer (OPC) is not yet fully established. The aim of this study was to disclose potential factor inducing biochemical relapse (BRFS) after BT for OPC patients (pts) when its strategy modified by D’Amico risk classification. Material and Methods From December 2004 to June 2014, 691 pts with low (280), intermediate (274), and high (137)-risk were treated with BT by real-time transrectal ultrasound-guided implantation under prescribed dose of 160Gy as monotherapy or 110Gy in combined with external beam radiotherapy (EBRT) delivering to prostate and seminar vesicle of 40Gy or 45Gy of each risk group. Anti-androgen therapy (ADT) of a mean 10.2 months was administered in 336 (49%) pts. All patients were followed at clinics with PSA determinations. The date of biochemical relapse was determined by the Phoenix (nadir + 2 ng/mL) definition. Interval between the date of last radiotherapy day (the RT day) and relapse day were calculated and constructed Kaplan-Meier plots. Differences in plots were evaluated by log-rank test among pts (KM-test) divided by risk classification, history of ADT, or combination of EBRT. In addition, The other proven factors were explored if it dichotomizes pts by different BRFS such as DVH parameters of BT or BT+EBRT, positive core rates of biopsy specimen (PCR), number of D’Amico risk class belong to intermediate or high. Results A total of 46 pts, 11/ 22/ 13 of each risk group, showed PSA relapse a mean 67.6 (6-135) months after the RT day. It accompanied distant bone metastasis (10), PSA increase >25 ng/ml (3) or regional lymph node metastasis (1). Twenty-four pts died during the study period due to the disease progression (2), cancer other than prostate or other disease (10). The BPFS achieved at 10 years was 91.1% for all patients. KM-test between low and intermediate risk pts showed significant difference (94.7 vs 88.7 %), but not between intermediate and high (88.7 vs 87.5 %). In intermediate pts, there were differences in the mean DVH parameters including pD 90 (179 vs 156 Gy, P=0.000), pV 100 (94 vs 90 %, p=0.001), or PCR (0.30 vs 0.39, p=0.024). Conclusion Intermediate risk group pts showed a BPFS similar to that of high risk. Those pts who relapsed had a higher risk of BPFS and were treated with RT degraded in dose and coverage. We need a modification in D’Amico intermediate classification and strategy. EP-1771 Low dose rate brachytherapy for prostate cancer: A Brazilian Institution experience. E.T.T. Leite 1 , J.L.F.D. Silva 1 , E. Capelletti 1 , G.N. Marta 1 1 Hospital Sirio Libanes, Radiation Oncology, Sao Paulo, Brazil Purpose or Objective Prostate cancer is the most common type of cancer in men, excluding nonmelanoma skin cancers. The main modalities of treatment are radical prostatectomy (RP), brachytherapy (BT), and external beam radiation therapy (EBRT) with or without androgen deprivation. BT is a treatment option with equal efficacy to EBRT or RP alone in patients with low- or intermediate-risk prostate cancer. The objective of this study was to estimate biochemical failure-free survival (BFFS), metastasis-free survival (MFS), disease-specific free survival (DSFS), overall survival (OS) and treatment-related toxicities in patients with prostate cancer who underwent LDR-BT alone in a single Brazilian Institution. Material and Methods