ESTRO 36 Abstract Book

S975 ESTRO 36 _______________________________________________________________________________________________

in the patients receiving additional external beam therapy. Conclusion The feasibility of HDR-BT as a treatment option in low, intermediate and high grade prostate carcinoma was confirmed. As previously expected, HDR-BT patients treated in a monotherapy setting showed a more favorable profile of detected side effects. In our experience HDR-BT can be implemented within a radiooncological department of a community hospital. EP-1773 Clinical outcomes in localized prostate cancer treated with HDR Brachytherapy as single fraction L. Larrea 1 , E. López-Muñoz 1 , P. Antonini 1 , V. Gonázlez 1 , M.C. Baños 2 , J. Bea 2 , M.A. García 2 1 Clinica Virgen del Consuelo, Radiation Oncology, Valencia, Spain 2 Clinica Virgen del Consuelo, Radiophysics Department, Valencia, Spain Purpose or Objective To describe the technique and analyze early outcomes in patients with low and intermediate risk prostate cancer treated with high dose rate brachytherapy (HDR) as monotherapy. Material and Methods From January to December 2015, 8 low and 8 intermediate prostate cancer patients were treated with 20 Gy HDR (Ir 192) as monotherapy, in one fractionation. At diagnosis, mean PSA was 7,42 ng/mL (range 6-16) and mean Gleason score was 6 (range 4-7). Any patient received androgen deprivation therapy. Mean prostate volume was 49 cc (range 21-67,3). Under rachianesthesia the patient is placed in a dorsal lithotomy position. A balloon catheter is placed into the bladder to correctly visualization of the urethra in transrectal ultrasonography (TRUS). Using a template, plastic needles are placed into the prostate through the perineal skin to the inside of the bladder. The template has needles holes at 5 mm intervals. Mean number of needles inserted was 13 (range 12-15). After implantation of needles TRUS 2 mm spaced axial images are taken for 3D treatment planning. Prostate delination was done as clinical target volume (CTV) and to evaluate dose constraints. PTV includes the whole prostate gland with a 2 mm posterior wall rectal margin and 5 mm all margins. Urethra was always defined. Dose constraints were: urethra total dose less than 120% and rectal dose less than 70% of the prescription dose. Prescription dose to prostate was 20 Gy. The minimal dose achieved to the 95% of the volume (D95) was 21-23 Gy (105-110%). All the procedure expends about 1-2 hours. Patients stay in hospital for 12 hours with urethral catheter. Genitourinary and gastrointestinal toxicity was evaluated in agreement with Common Terminology Criteria for Adverse Events (CTCAE v4.03). For sexual function the International Index of Erectil Function Questionnaire was used. The global cost is a forfait for all the procedure. Results With a median follow-up of 15,1 months (range 10-21) all patient survive without progression. Mean PSA after treatment was 1,4 ng/mL (range 0,21-3,37). Three patients presented acute disuria and one patient urinary urgency (grade 1) that were resolved in less that 3 weeks. Erectil function preservation was 87,5%. No gastrointestinal toxicity was observed. One patient was diagnosed of lung cancer two months after brachytherapy treatment. The overall cost treatment was among €- 10.000 per patient (€-9.000-14.000). Conclusion

In our experience, HDR brachytherapy using extreme hypofractionation is a safe and well tolerated alternative to permanent-seed implants with a high local control disease and low toxicity rates. Some advantages as “in vivo” prescription, short surgical time and no radioactive procedure were confirmed. However, long-term follow-up is needed to confirm our initial results. EP-1774 Randomized phase II trial of IGRT with or without HDR boost in intermediate-risk prostate cancer E. Vigneault 1 , G. Morton 2 , W. Perulekar 3 , T. Niazi 4 , G. Springer 5 , M. Barkati 6 , P. Chung 7 , W. Koll 8 , A. Kamran 9 , M. Montreal 3 , K. Ding 3 , A. Loblaw 2 1 CHU de Québec- L'Hôtel Dieu de Québec, Radiation Oncology and Research Centre, Quebec, Canada 2 Odette Cancer Centre, Radiation Oncology, Toronto, Canada 3 Canadian Cancer Trials Group, Queen 's University, Kingston, Canada 4 Mc Gill Jewish General Hospital, Department of Radiation Oncology, Montreal, Canada 5 Windsor Regional Hospital, Radiation Oncology, Windsor, Canada 6 CHUM Hôpital Notre Dame, Radiation Oncology, Montreal, Canada 7 University Health Network Princess Margaret Cancer Centre, Radiation Oncology, Toronto, Canada 8 Lakeridge Hospital, Radiation Oncology, Oshawa, Canada 9 Dr H Bliss Murphy Cancer Centre, Radiation Oncology, St-John's, Canada Purpose or Objective The purpose of this phase II randomized feasibility study was to assess the ability of Canadian investigators from multiple institutions to randomize patients to IGRT (Image Guided Radiotherapy) or IGRT with HDR (High Dose Rate) brachytherapy boost and to deliver the treatment according to the highest radiation oncology quality assurance benchmarks and standards. Material and Methods The primary endpoint was to determine the ability to randomize 60 patients over an 18 months period. Arm 1 (IGRT) patients received 78 Gy in 39 fractions or 60 Gy in 20 fractions (physician’s preference) while Arm 2 (IGRT + HDR) received 37.5 Gy in 15 fractions with HDR boost of 15Gy. IGRT options were daily imaging with prostate fiducial markers, cone/fan beam CT images, or ultrasound localization system. The secondary endpoints included: acute genitourinary (GU) and gastrointestinal (GI) toxicity, using NCI Common Terminology Criteria for Adverse Events (CTCAE V 3.0) at 3 months, validation of a prospectively defined radiation oncology quality assurance process including real time peer review and treatment compliance. All analyses were descriptive; no formal comparisons between treatment arms were performed. Results Between April 2014 and September 2015, 57 NCCN defined intermediate risk prostate cancer patients were randomized between IGRT alone (Arm 1) N=29, vs. IGRT plus HDR brachytherapy boost (Arm 2) N= 28. Overall, 93.0% received the treatment as randomized. There were 4 patients (1 on IGRT arm 1 and 3 patients on the IGRT+HDR arm 2) who were treated differently from randomization assignment. For the 29 patients receiving IGRT (arm 1), there were 14 cases reported with minor deviations and 3 with major deviations. For patients on IGRT+HDR (arm 2), there were 18 cases reported with minor deviations and 2 with major deviations. At 3 months in the IGRT group (Arm 1), one patient reported grade 3 diarrhea while in the IGRT+HDR group (Arm 2), two patients reported grade 3 hematuria. No other GI and GU toxicities were reported.