Abstract Book

S1253

ESTRO 37

Conclusion Manual needle distribution does not negatively impact on the number of needles implanted per patient, so prostate trauma is not compromised. It provides excellent coverage and possibly a more robust implant as in the needle position other factors apart from the mathematical optimization of HIPO are taken into account. EP-2269 Survial Endpoints Comparing HDR BT Boost To EBRT Boost For High/Intermediate-Risk Prostate Cancer. S. Rodriguez Villalba 1 , J. Richart Sancho 1 , J. Pérez- Calatayud 2 , J.D. Lago Martin 1 , M. Santos Ortega 1 1 hospital Clinica Benidorm, Radiation Oncology Department, Benidorm, Spain 2 hospital La Fe-Irimed, Radiation Oncology Department, Valencia, Spain Purpose or Objective Brachytherapy (BT), High Dose Rate (HDR) are employed as a boost for intermediate (IR) (PSA 10-20 ng/ml, Gleason ≤ 7 and ≤ T2c) and high risk (HR) (PSA >20 ng/ml, Gleason 8-10 and ≥T3) prostate cancer. A retrospective analysis in 261 consecutives organ confined prostate cancer patients treated from October 2004 to December 2015 has been made for evaluating the clinical results and toxicity comparing EBRT exclusive with combined treatments of EBRT and a HDR BT component. Material and Methods Median age was 70 years (range 48-87 y). Median PSA at diagnostic was 11, 8 ng/ml (range 2, 26-500 ng/ml). Median Gleason 7 (range 3-10). A MRI for staging was done in 202 pts (77 %). We have treated 109 (42 %) patients staged as IR and 152 (58%) patients staged as HR. Ninety seven patients (37%) have received EBRT followed to an external beam radiotherapy boost (EBRT-b) with IGRT. Median total dose 75, 6 Gy (range 50,4-81 Gy) and 164 patients (63%) a boost with HDR BT (HDR BT-b) (10 Gy in IR patients, 2 fractions of 9,5 Gy or 1 fraction of 15 Gy in HR patients). Two hundred and forty nine patients (95 %) have received androgen deprivation therapy (ADT) (6 months in IR and 24 months in HR). Results At the time of this analysis, October 2017, the median follow up was 45 months (range 8- 163 m). The 5, 7 and 9 years Kaplan Meier biochemical progression free survival (b-PFS) estimates were 95%, 93% and 93 % for HDR BT-b versus 75%, 70% and 62% for EBRT-b respectively (log rank p=0,02 ). The HDR BT boost benefits both IR and HR patients. No difference was seen between the HDR BT-b or EBRT-b groups with regards to overall survival (OS), prostate cancer specific survival (PCSS), lymph node control or local control. The 5, 7 and 9 years Kaplan Meier distant metastases free survival (DMFS) estimates were 97%, 95% and 95 % for HDR BT-b versus 85%, 85% and 85% for EBRT-b respectively (log rank p=0,02 ). Toxicity has been analyzed based CTCAE.4 criteria. Four patients (1,5%) had acute urinary obstruction in all cases treated with HDR-BT boost. Chronic GI toxicity grade 3 (radiation rectitis) has been developed in 24 pts (9%), 14 patients (58%) treated with EBRT-b and 10 patients (42%) treated with HDR BT-b. In all cases (100%) toxicity has been solved being treated with Argon laser (Median 1 application (1-8). Conclusion In our experience, combination modality with external radiotherapy an a HDR BT boost provide in intermediate and high risk prostate cancers patients excellent rates with statistical improvements in biochemical progression and distant metastases free survival when it is compared with other boost modalities.

(GI) and genitourinary (GU) toxicity were analyzed by univariate analysis. Results Neither acute nor late grade 2 to 3 GI toxicities developed. Acute grade 2 GU toxicity occurred in 11.4% (grade 3 in 0.0%). Any predictors of acute grade 2 GU toxicity weren’t founded. Late grade 2 to 3 GU toxicity occurred in 23.8% (grade 3 in 2.9%). Grade 2 urethral obstruction, urinary tract pain, urinary urgency, urinary frequency, hematuria, and grade 3 urethral obstruction were observed in 9, 2, 7, 7, 4, and 3 patients, respectively. Any predictors of late grade 2 to 3 GU toxicity weren’t also founded. Conclusion There was no statistically-significant correlation between the incidence of Grade 2 to 3 GI and GU toxicity and the clinical and dosimetric factors after HDR brachytherapy as monotherapy in localized prostate cancer. EP-2268 HDR prostate brachytherapy planning: impact of manual vs automated needle distribution M. Gaztañaga 1 , C. Prieto 2 , V. Jarabo 3 , G.M. Vázquez 1 , D.F. Martínez 2 , D.P. Córdoba 2 , M. De las Heras 1 1 Hospital Clinico San Carlos, Oncología Radioterapia, Madrid, Spain 2 Hospital Clinico San Carlos, Física Médica, Madrid, Spain 3 Hospital Ramón y Cajal, Oncología Radioterapia, Madrid, Spain Purpose or Objective Automated needle positioning with HIPO (hybrid inverse planning and optimization) algorithm has been the standard modus operandi in our institution from 2011 to 2016. Whereas this algorithm calculates theoretically optimal dosimetries, there is a number of potential uncertainties during implantation (such as narrow pubic bones, lateralized or anfractuous urethras, impact of edema or wide prostates) where the proposed distribution of catheters is not achievable. The aim of this study is to evaluate the dosimetric effect of manual needle distribution (MND) in real time HDR prostate brachytherapy. Material and Methods Treatment plans of 115 consecutive patients using MND were evaluated. Prostate maximum area (in transversal slices), volume, dosimetric parameters and dose homogeneity index (DHI) were calculated. The number of blocked positions due to urethral course was recorded. HIPO proposed number of needles was compared with the MND one. Results No statistically significant differences were found in the number of needles used with MND: median 14.8 needles with HIPO and 14.7 in MND ( p=ns ). The number of needles implanted was not correlated with the prostatic volume or blocked positions due to urethral course but prostates with a larger cross-section required more needles. Median prostate coverage was V100: 98.9% (SD 0.75) and median DHI was 0.67 (SD 0.05).