ESTRO 36 Abstract Book

S195 ESTRO 36 2017 _______________________________________________________________________________________________

Seventy-one patients were identified. Bladder invasion was diagnosed either on imaging in 59% or endoscopically/histologically proven in 41%. All patients received pelvic external beam radiotherapy (EBRT), 45 Gy in 25 fractions ± nodal boost to macroscopically involved lymph nodes. Nineteen of the 21 patients with para-aortic nodal metastases received para-aortic EBRT. Concurrent platinum-based chemotherapy (CT) was used in 76%, neoadjuvant CT was used in 14%. After EBRT, 64 patients (90%) received uterovaginal BT (low-dose rate in 48%, pulsed-dose rate in 52%). Eight patients had VVF at diagnosis. Among the 63 patients without VVF at diagnosis, 14 patients (22.2%) developed VVF later on: four before (28.6%) and ten (71.4%) after BT (median time to onset: 3.5 months after the start of EBRT). Twelve of the 22 patients (54.5%) who presented VVF, either at diagnosis or during follow-up, needed surgery (urinary or bowel diversion ± pelvectomy). Estimated OS, PFS and LCR at 2 years were 57.3% (44.9-68.8), 45.0% (32.3-58.5) and 69.1% (54.4-80.7) respectively. Presence of para-aortic nodal metastases was significantly associated with poorer OS on multivariate analysis (HR=4, p<0.001). Only the presence of necrosis in the anterior part of the tumor on baseline MRI was strongly associated with the risk of subsequent VVF (57% vs O% at 1 year, HR=16.7, p=0.011 on a multivariate analysis taking into account the tumor volume). No correlation was found between bladder dose and risk of VVF.

Figure: Descriptive statistics of D98 of pathologic nodes according to regions. Ext: external iliac, Int: internal iliac, Ing: inguinal, Com: common iliac, Obt: obturator, Sac: presacral, Cent: central (pararactal or parametrial). Red cross: mean value, blue diamond: minimal and maximal values, lower limit of the box: first quartile, upper limit of the box: third quartile, central horizontal bar: median, whiskers: from minimal value to 1.5 x box length. Thus, to deliver a cumulative EQD2 ≥60 Gy to pathologic nodes accounting a pelvic external beam radiation dose of 45 Gy in 25 fractions (44.3 in EQD2) and these estimations, we propose nodal SIB of 2.2 Gy x 25 (55 Gy, 55.9 in EQD2) in the obturator, external and internal iliac nodes, 2.3 Gy x 25 (57.5 Gy, 58.9 in EQD2) in the common iliac nodes, and 2.4 Gy x 25 (60 Gy, 62 Gy in EQD210) in the para-aortic nodes (where the BT contribution can be considered as negligible). Conclusion The contribution of brachytherapy to the treatment of pelvic nodes is significant: around 5 Gy in the obturator, internal iliac, and external iliac areas and 2.5 Gy in the common iliac, allowing the use of simultaneous integrated boost. However, important individual variations have been observed and evaluation of the genuine individual brachytherapy contribution is recommended. OC-0366 Cervical cancer with bladder invasion: outcomes and vesicovaginal fistula prognostic factors R. Sun 1 , R. Mazeron 1 , I. Koubaa 2 , I. Dumas 3 , C. Baratiny 1 , F. Monnot 1 , P. Maroun 1 , E. Deutsch 1 , P. Morice 4 , C. Haie- Meder 1 , C. Chargari 1 1 Gustave Roussy, Radiation oncology, Villejuif, France 2 Gustave Roussy, Radiology, Villejuif, France 3 Gustave Roussy, Medical physics, Villejuif, France 4 Gustave Roussy, Surgery, Villejuif, France Purpose or Objective Although brachytherapy (BT) is a mainstay of the treatment of locally advanced cervical cancer, there are only scarce data on its efficiency in cervical cancer with bladder invasion. The aims were to report the treatment outcomes in this particular situation, as well as vesicovaginal fistula (VVF) incidence and its prognostic factors. Material and Methods Consecutive patients with locally advanced cervical cancer and bladder invasion treated in our institution from 1989 to 2015 were identified. Demographic and tumor features, treatment characteristics, VVF rate, progression-free survival (PFS), local control rate (LCR), and overall survival (OS) were reviewed. Baseline magnetic resonance imaging (MRI) scans reviews were carried out blind to the clinical data with focus on radiological parameters potentially correlated to the risk of VVF (necrosis, tumor height of bladder involvement, tumor volume). Times were calculated from the date of diagnosis. Survival were estimated using the Kaplan-Meier method and the Cox proportional hazards model. Results

Conclusion A curative intent strategy including BT as part of local treatment is feasible in patients with bladder invasion, with a rate of 22% of post-treatment VVF. MRI has a strong predictive value of VVF occurrence. This result has to be confirmed in an independent cohort. Prognosis remains poor in regard to lower-staged lesions, with a high risk of out-of-field failure. Intensification of systemic therapies should be considered. OC-0367 Dose-response curve for vaginal stenosis. Final results of a prospective study. M. Federico 1 , A. Tornero 2 , S. Torres 2 , B. Pinar 1 , M. Rey Baltar 1 , M. Lloret 1 , P. Lara 1 1 Hospital Universitario de Gran Canaria Dr. Negrín, Radiation Oncology, Las Palmas de Gran Canaria- Ca, Spain