PO-0755: Prophylactic extended-field carbon-ion radiotherapy for locally advanced uterine cervical cancer

S42 4. 37 (37/123, 30%) patients were assessed as image-positive with minimal axial diameterof 10.2±3.6mm(range from 8 to 25mm) in CT images and pathology-negative 5. 74 (74/123, 60% ) patients were not only image-negative, but also pathology-negative 6. 10 (10/123,8% ) patients were image-positive with minimal axial diameter of 19±5.9mm (range from 10 to 28 ) in CT images and pathology-positive 7. 25 patients had enlarged lymph nodes with minimal axial diameter of more than or equal to 10mm in CT images. 10 of them had pathological metastasis. While, 22 patients with enlarged lymph node with minimal axial diameter of less than 10 mm, there is no pathological metastasis in H-E slides after CCRT. Conclusions: For the patients with squamous carcinoma, image-negative or enlarged lymph node of minimal axial diameter of less than 10mm in CT images with contrast, the probability of pathology-positive in pelvic nodes only was 1.04% after neoadjuvant CCRT. The lymphadenectomy would be omitted in this group of patients. However, the outcome would need to be confirmed in randomized controlled trial. PO-0755 Prophylactic extended-field carbon-ion radiotherapy for locally advanced uterine cervical cancer M. Wakatsuki1, S. Kato2, T. Ohno3, K. Karasawa1, D. Irie1, K. Ando3, H. Kiyohara3, T. Nakano3, T. Kamada1, M. Shozu4 1 National Institute of Radiological Sciences, Research Center Hospital for Charged Particle Therapy, Chiba, Japan 2 Saitama Medical University International Medical Center, Department of Radiation Oncology, Saitama, Japan 3 Gunma University Graduate School of Medicine, Department of Radiation Oncology, Gunma, Japan 4 Graduate School of Medicine Chiba University, Departments of Reproductive Medicine, Chiba, Japan Purpose/Objective: The authors performed phase I/II clinical trials to evaluate the toxicity and efficacy of prophylactic extended-field carbonion Radiotherapy (C-ion RT) for locally advanced squamous cell carcinoma of the uterine cervix

ESTRO 33, 2014 Purpose/Objective: The aim of this study is to test the method for investigating the dosimetric patterns of nodal failure (either a recurrence or persistent disease) in cervical cancer patients treated within the EMBRACE study. Materials and Methods: EMBRACE is a multicenter prospective observational study investigating the impact of MRI guided 3D brachytherapy (BT) on outcome in locally advanced cervical cancer. Treatment consists of a combination of external beam radiotherapy (EBRT), MRI guided BT and concomitant chemotherapy. For the present study, we used data from patients treated in our institute in order to test a method that allows determining the delivered dose at site of individual nodal failure. According to our institutional protocol the elective pelvic nodal regions are treated with EBRT to 44.3 Gy EQD2 α/β10. Elective para-aortic irradiation to L1-L2 is given if pathological nodes are found at the level of common iliac or higher. PDR or HDR BT is given to the high risk CTV with a planning aim D90% of 39.8 Gy EQD2 α/β10. In addition, pathological nodes are boosted with EBRT to 10 or 14 Gy dependent on the BT dose to these nodes. Individual nodal failures were delineated on MRI data sets at time of nodal recurrence. These MRI data sets as well as the BT MRI data sets were rigidly registered to the planning CT scans. To investigate the delivered dose to the location of the detected failure EBRT dose maps (elective and boost) as well as the BT dose maps were linked to the planning CTs. The total delivered dose including EBRT elective, EBRT boost and BT were calculated for each nodal failure. Results: In our institute 56 patients were treated within the EMBRACE study from January 2009 till January 2013. Six of them developed a total of 9 nodal recurrences. Three recurrences appeared outside the electively treated volume (PTV-E) in the para-aortic regions, 3 inside the PTV-E and 2 at the treatment field border of a boosted node (PTV-N) and 1 within a PTV-N. Delivered dose to regions with nodal failure differed considerably. Nodal failure within PTV-N occurred even after having delivered a D98% of 63 Gy EQD2 α/β10 .

Materials and Methods: The eligibility criteria for enrollment in this study were (1) histologically proven squamous cell carcinoma, (2) FIGO stage IIB, IIIB, or IVA, disease without rectal invasion (3) maximum tumor diameter > 4cm (4) aged < 80 years (5) no prior treatment, and (6) a expected prognosis of more than 6 months. The treatment consisted of extended-field irradiation of 39.0 gray equivalents (GyE) for 13 fractions and additional 15.0 GyE for 5 fractions was given to the gross tumor volume (GTV) and surrounding tissues. With regard to local boost, 18.0 GyE for 2 fractions was given to GTV only. Total dose to the cervical tumor was 72.0 GyE for 20 fractions. Twenty-six patients who matched eligibility criteria enrolled into this study between April 2005 and February 2012. The number of patients with stage IIB, IIIB, and IVA disease were 13, 11, and 2, respectively. Twenty patients had pelvic lymph node metastases. Median tumor size was 6.1 cm (range, 4.0-10 cm). Results: The median follow-up period was 30 months. Although 1 patient developed grade 4 of acute leukopenia and 21 patients had grade 1 or 2 acute gastrointestinal toxicity, all patients completed the treatment on schedule. There was no grade 3 or higher late complications, 8 patients observed grade 1 or 2 toxicities: G2 toxicity was detected 3 patients (12.7%): 2 patients for bladder and 1 patient for rectal complication. Five patients (19.2%) developed local recurrence, and 9 patients (34.6%) had distant metastases. The 2-year local control rate, progression free survival rate and overall survival rate were 78.0 %, 61.3 % and 75.7 %,respectively. Conclusions: Prophylactic extended-field C-ion RT for locally advanced squamous cell carcinoma of the uterine cervix was a safe treatment. Although the number of patients in this study was small, the results support further investigations to confirm the therapeutic efficacy. PO-0756 Total dose to sites of nodal failure in cervical cancer patients: A sub study in EMBRACE P. Kroon1, A. De Leeuw1, J. Cnossen1, K. Tanderup2, J. Lindegaard2, R. Pötter3, I. Jürgenliemk-Schulz1 1 UMC Utrecht, Department of Radiotherapy, Utrecht, The Netherlands 2 Aarhus University Hospital, Department of Oncology, Aarhus, Denmark 3 Medical University of Vienna, Department of Radiotherapy, Vienna, Austria

Conclusions: With the described method of dose adding we are able to determine the dosimetric patterns of nodal failure in cervical cancer patients. Nodal failures occurred outside the radiation fields, suggesting a deficit in treated volume, as well as inside or at the borders of the treated volumes, suggesting a deficit in dose. This study will be extended to other EMBRACE centers aiming at more detailed knowledge on the dosimetric patterns of nodal failure and the required dose to suppress them. PO-0757 Definitive radiotherapy for cervix cancer ñ a single institution experience with 10-years follow-up B. Segedin1, R. Hudej1, H.B. Zobec Logar1, P. Petric2 1 Institute of Oncology Ljubljana, Department of Radiation Oncology, Ljubljana, Slovenia 2 National Center for Cancer Care and Research, Department of Radiation Oncology, Doha, Qatar