ESTRO 37 Abstract book

ESTRO 37

S568

Conclusion In the current brachytherapy cohort, moderate correlation was observed for overall cosmesis score as well as nipple location domains while comparing physician rated subjective assessment with BCCT.core derived objective indices.

months, 12/41 developed metastases during the observation period. Actuarial LC, PFS, and OS rates at 2/5 years were 94/94%, 69%/66%, and 82%/74%, respectively. All 4 ≥G3 toxicities occurred in this group. Conclusion Loco-regional recurrence in previously surgically treated EC patients can be successfully salvaged with modern radiation techniques including IGABT. Previous radiation does not preclude salvage therapy. If the relapse is limited to the vaginal wall, IGABT may be the therapy of choice, while in recurrences extending beyond the vaginal cuff and/or involving the pelvic lymph nodes a combination with pelvic EBRT seems appropriate. PO-1016 TRUS/CT for IGABT in cervical cancer: an interobserver study on target volume contouring S. Smet 1,2 , N. Nesvacil 2,3 , J. Knoth 2 , A. Sturdza 2 , D. Najjari-Jamal 4 , F. Jelinek 5 , G. Kronreif 5 , R. Pötter 2,3 , J. Widder 2 , C. Kirisits 2,3 , M.P. Schmid 2 1 University Hospitals Leuven, Department of Radiation Oncology, Leuven, Belgium 2 Medical University of Vienna, Department of Radiation Oncology- Comprehensive Cancer Center, Vienna, Austria 3 Medical University of Vienna, Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Vienna, Austria 4 Institut Català d'Oncologia- Hospitalet de Llobregat, Department of Radiation Oncology, Barcelona, Spain 5 Austrian Center for Medical Innovation and Technology, ACMIT, Wiener Neustadt, Austria Purpose or Objective To compare the interobserver variability of combined transrectal ultrasound (TRUS) / computed tomography (CT) vs. CT only vs. MRI only based contouring of the high risk clinical target volume (CTV HR ) in image guided adaptive brachytherapy (IGABT) for locally advanced Five patients with LACC (FIGO stages IIb - IVb) treated with radiochemotherapy and IGABT were included in this prospective study. CT, TRUS and T2-weighted MRI images were performed after insertion of the BT-applicator. 3D TRUS image acquisition was done with a customized US stepper device and software (Medcom, Germany; Elekta, Sweden; Acmit, Austria). Automatic applicator reconstruction using optical tracking was performed directly in the TRUS data set and then TRUS and CT images were fused with rigid image registration with the applicator as reference structure. The CTV HR (based on the recommendations of the GYN GEC-ESTRO group) of each patient was contoured on the 3 imaging modalities independently by 5 experienced investigators, generating CTV HR _CT, CTV HR _TRUS-CT and CTV HR _MRI. A consensus reference CTV HR _MRI (MRIref) was defined for each patient. Descriptive statistics and overlap measures (generalized conformity index) were calculated using RT slicer, comparing contours of every observer with one another and with the MRIref. Results The descriptive statistics are summarized in table 1 and show a generalized conformity index (CI gen) of 0.79±0.04 for all CT contours, 0.80±0.05 for all TRUS-CT contours and 0.86±0.02 for all MRI contours. The interobserver variation in relation to the MRIref volume is larger for CT (CIgen=0.52±0.05), than for TRUS-CT (CIgen= 0.63±0.06), and smallest for MRI (CIgen=0.84±0.02). The mean CTV HR _CT volume of all observers was 71% larger than the MRIref volume (55%, cervical cancer (LACC). Material and Methods

Poster: Brachytherapy: Gynaecolgy

PO-1015 Image-guided salvage radiotherapy of pelvic recurrences in post-hysterectomy endometrial cancer J. Knoth 1 , D. Berger 1 , R. Pötter 1 , M. Schmid 1 , C. Grimm 2 , V. Seebacher 2 , S. Polterauer 2 , J. Widder 1 , A. Reinthaller 2 , A. Sturdza 1 1 Medical University of Vienna, Radiation Oncology, Vienna, Austria 2 Medical University of Vienna, Gynecology, Vienna, Austria Purpose or Objective To evaluate response, local control (LC), progression free survival (PFS), overall survival (OS), and toxicity in recurrent endometrial cancer (EC) in patients undergoing image guided adaptive brachytherapy (IGABT) w/o external beam radiotherapy (EBRT). Material and Methods A retrospective analysis of consecutive patients undergoing radiotherapy for local/loco-regional recurrence of EC treated initially with surgery was performed (2001-2016). Irradiation included IGABT alone in patients with superficial tumors limited to the vaginal wall and N0 status - Group 1 (Gr1). Group 2 (Gr2) included patients with recurrences extending beyond the vaginal wall and/or to the regional lymph nodes. Treatment was standard pelvic EBRT (45 Gy) + IGABT. IGABT was performed using MRI- (70 %) or CT-guidance (30%) at least at the first fraction. The primary/residual tumor was contoured as clinical target volume; the whole vaginal wall as low risk clinical target volume. Planning aim to the whole vaginal wall was 60 Gy and to the rest tumor 85 Gy. Response rate, actuarial LC, PFS, and OS were calculated; long term toxicity was recorded using CTCAEv4 criteria. Results Median age of the cohort (n=52) was 76 years (53-91), median follow up after recurrence treatment 49 months (range 2-184). All patients had an EC type I histology initially, while 13 (25%) recurred with a more aggressive histology (Type II). Median time to recurrence after initial surgery was 26 (5-130) months. Eleven patients had previous pelvic EBRT (n=5) or BT (n=6). Response rate was 95%, actuarial LC, PFS, and OS rates at 2/5 years were 95%/95%, 74%/69%, and 85%/78%, respectively. In 4 patients (8%) ≥G3 GU toxicity (vesico-vaginal fistula, vaginal stenosis) and/or recto-vaginal fistula occurred, of whom two had previous adjuvant IGABT/ EBRT. In Gr1 (n=9), median age was 70 years (53-78), median FU 46 months (6-90). One patient had previous pelvic EBRT. All had complete remission after treatment completion. One patient developed pelvic lymph node recurrence. Actuarial LC, PFS and OS rates at 2/5 years were 100%/100%, 100%/83%, and 100%/100%, respectively. No grade ≥3 toxicity occurred. In Gr2 (n=43), median age was 77 years (53-91), median FU 49 months (2-184). Two patients had incomplete local remission and developed lung metastases within 3