ESTRO 36 Abstract Book

S974 ESTRO 36 _______________________________________________________________________________________________

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, Japan 2 Iwate Medical University, Urology, Morioka, Japan 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 Patients treated with Iodine-125 BT with post-implant dosimetry after at least 5 years of follow-up were retrospectively assessed. Patients who received combination therapy (EBRT and BT) and salvage BT were excluded. Results From 616 patients treated between March 2001 and November 2010, 406 of them were included in the study. 65.5% were low-risk; 30%, intermediate-risk; 4.5%, high- risk. After a median follow-up of 87.5 months, 61 (15.0%) patients developed biochemical recurrence. BFFS at 5 and 10 years was 90.6% and 82.2% respectively. There were no significant differences in the BFFS among the risk groups (p = 0.294). Nadir ≥ 1 ng/ml was associated with higher risk of biochemical failure (HR = 5.81; CI 95%: 3.39 to 9.94; p ≤ 0.001). MFS at 5 and 10 years was 98.3% and 94% respectively. Three patients (0.3%) died from prostate cancer during follow-up. OS at 5 and 10 years was 96.2% and 85.1% respectively. Acute and late grade ≥ 2 and grade ≥ 3 gastrointestinal toxicity were observed in 5.6% and 0.5% and 4.6% and 0.5%, respectively. Acute and late grade ≥ 2 and grade ≥ 3 genitourinary toxicity were 57.3%, 3.6% and 28%, 3.1%, respectively. Conclusion Iodine-125 LDR-BT is a safety and efficient treatment for well-selected prostate cancer patients. EP-1772 HDR Brachytherapy in the treatment of Prostate Cancer – the Vienna Experience O. Komina 1 , C. Seitz-Kästner 1 , J. Hofbauer 1 , M. Kuntner 1 , J. Wimmer 1 , T. Knocke-Abulesz 1 , E. Nechvile 1 1 KH Hietzing mit Neurologischem Zentrum Rosenhügel, Sonderabteilung für Strahlentherapie, Wien, Austria Purpose or Objective Radiation Therapy (RT) plays a crucial role in the treatment of prostate cancer. The advantage of high dose rate brachytherapy (HDR-BT) as monotherapy or boost to deliver high radiation dose to the tumor and to spare organs at risk (OAR) was recently shown in clinical studies. Material and Methods We summarized the overall patient data collected in our institution since 2010 when we implemented the real time planning system based on 3D ultrasound imaging. Between 2010 and 2015 a total of 256 patients were treated and 584 implants being performed. 47% of the patients with local disease received HDR-BT alone (4 x 9 Gy on a weekly basis [n= 22], after 2012 3 x 10,5 Gy every other week [n= 99]). 53% of the patients received combination therapy for treatment of intermediate or high-risk prostate cancer. These patients received one or two fractions of HDR-BT with the doses of 9 or 10,5 Gy respectively combined with local external beam RT of the prostate only or additional pelvic lymph node irradiation. 17 patients were treated in terms of salvage therapy after radical prostatectomy (RPE), external beam or brachytherapy. Results Median age was 69,2 years (range 44,8 - 87,5). The majority of patients (37%) had Gleason 6 histology, 29% Gleason 7a, and 9% 7b. High risk patients receiving exclusively combination therapy had Gleason 8 in 13%, Gleason 9 in 11% and Gleason 10 in 1% of the cases. The median V100 for the prostate was 93,7%. No acute grade ≥3 toxicity was observed in the whole cohort of the patients. Late rectal toxicity was observed predominantly