ESTRO 2021 Abstract Book

S1122

ESTRO 2021

W. Majewski 1 , D. Lange 2 , A. Stanek-Widera 2 , B. Itrych 3 , T. Krzysztofiak 4 , M. Jarzab 5 , M. Oczko- Wojciechowska 6 , R. Tarnawski 7 1 Maria Sklodowska-Curie National Research Institute of Oncology, Gliwice Branch, Radiotherapy Department, Gliwice, Poland; 2 Maria Sklodowska-Curie National Research Institute of Oncology, Gliwice Branch, Department of Pathology, Gliwice, Poland; 3 Centre of Postgraduate Medical Education, Department of Breast Cancer, Warsaw, Poland; 4 Maria Sklodowska-Curie National Research Institute of Oncology, Gliwice Branch, Department of Brachytherapy, Gliwice, Poland; 5 Maria Sklodowska-Curie National Research Institute of Oncology, Gliwice Branch, Breast Unit, Gliwice, Poland; 6 Maria Sklodowska-Curie National Research Institute of Oncology, Gliwice Branch, Department of Genetic and Molecular Diagnostics of Cancer, Gliwice, Poland; 7 Maria Sklodowska-Curie National Research Institute of Oncology, Gliwice Branch, III Clinic of Radiotherapy and Chemotherapy, Gliwice, Poland Purpose or Objective Although the WHO 2016 grading classification in prostate cancer indicates large differences between Grading Groups, we assumed that in patients treated with radiation therapy (RT) +/- hormonal treatment (HT) some differences might not be so pronounced, especially between Gleason 3+4 and 4+3 (Grading Group 2 and 3). Other pathology details like nerve invasion, cribriform pattern and number of involved cores may be of importance. Hence, we re-evaluated pathology specimens in patients with Gleason score 7 who underwent a radical RT and had a long-term follow-up. Materials and Methods The study group consist of 139 patients with prostate cancer and initial Gleason score 7 (3+4 or 4+3) treated with 3DCRT or IMRT between 2008 and 2013. Patients were treated with conventionally fractionated RT to the total dose of 76 Gy with 2 Gy per fraction, in 45% of patients pelvic lymph nodes were irradiated. HT was implemented in 88% patients before referral to RT. There were 45% and 55% patients in the intermediate and high-risk group, respectively. The original pathology specimen was re-evaluated, according to the contemporary experience. The clinical outcome was assessed with respect to the biochemical control. The importance of selected factors from the re-evaluated pathology report was assessed. Results The median follow-up was 53 months. The 5-year biochemical control was 89%. After re-evaluation majority of patients (96 pts-69%) were up-graded from Gleason 7 to higher scores. Finally, there were 4 patients (3%) Gleason 3+3, 12 patients (9%) Gleason 3+4, 27 patients (19%) Gleason 4+3, 51 patients (37%) Gleason 4+4 and 45 patients (32%) with higher Gleason sum. In 42 patients (30%) a cribriform pattern was observed, in 38 patients (27%) neuro-invasion was noted. The median number of involved cores was 3 and the median percentage of involved cores was 40%. Among the analyzed factors only the Gleason score (p=0.011) was important for biochemical control and a cribriform pattern was of borderline importance (p=0.05). We observed no biochemical recurrences in patients in patients with Gleason score ≤4+3, 14% of patients with Gleason score 4+4 experienced biochemical recurrences and 13% of patients with Gleason score 4+5, 5+4, 5+5. The 5-year biochemical control was 100% if Gleason score was ≤4+3 vs 84% for others. If the cribriform pattern was present there were 17% biochemical recurrences as compared to 6% of recurrences if no cribriform pattern was revealed. The 5-year biochemical control was 93% and 81%, respectively. Conclusion Re-evaluation and verification of pathology specimen according to the contemporary rules up-graded the Gleason score in majority of patients. The aggressive behavior of prostate cancer starts to occur from Gleason score 4+4. The cribriform pattern almost tripled the biochemical failure rate. PO-1369 HDR Brachytherapy Monotherapy in patients with Low/Intermediate-risk Prostate Cancer E. Moreno Olmedo 1 , G. Nagore 2 , V. Suárez Gironzini 1 , C. Minguez 3 , E. Gómez 4 , A. Garcia 4 , V. Ciapa 5 , I. Marrone 1 , E. López 1 1 GenesisCare Spain, Radiation Oncology, Hospital Vithas La Milagrosa, Madrid, Spain; 2 GenesisCare Spain, Radiation Oncology, Hospital Vithas Alicante, Alicante, Spain; 3 GenesisCare Spain, Radiphysics, Hospital Vithas La Milagrosa, Madrid, Spain; 4 GenesisCare Spain, Radiophysics, Hospital Vithas Alicante, Alicante, Spain; 5 Genesiscare Spain, Radiation Oncology Nurse, Hospital Vithas La Milagrosa , Madrid, Spain Purpose or Objective To evaluate the feasibility and toxicity of high-dose-rate (HDR)-brachytherapy (BT) as monotherapy in a prospective clinical trial consisting in two sessions interval 6 hours of a single implant for localized prostate cancer. We report the Acute and Chronic Genitourinary (GU) and Gastrointestinal Toxicity (GI) and Disease Control. Materials and Methods Between November 2010 and October 2020 a total of 119 patients were treated. The prescribed dose was 27 Gy in 2 fractions in a day using a single implant. 24 patients (20.1%) was Intermediate risk cancer. 39 patients (33%) received hormonal therapy. Biochemical prostate-specific antigen (PSA) failure was per the Phoenix definition. GU and GI toxicity were evaluated by CTCAE V 4.0. Sexual Function were recorded during follow-up Results Median follow-up was 100 months (range, 33-119). Grade 1-2 acute Toxicity was 26.9%, mainly Frequency/urgency (10%), Dysuria (10%), Dribbling/hesitancy (0.8%). 3 patients required a Foley catheter during 1 week. No acute GI toxicities were recorded. Chronic Genitourinary Toxicities Grade 1-2 were 28.5 %, mainly Dysuria (12.6%), Urinary frequency/urgency (5.8%) and Urinary Incontinence Grade 2 (1.6%); 1 patient had Grade 2 rectal bleeding and 1 patient had Grade 3 GU toxicity requiring RTU. 23.7% of patients without Hormonal therapy reported sexual impotence Grade 1-2 after 2 years therapy. The actuarial Local Control was 99.2%, Biochemical Control 95.8%, Distant Failure 4.2% and Overall Survival was 91.6% Conclusion HDR brachytherapy as monotherapy with longer follow up for localized prostate cancer is an effective