ESTRO 36 Abstract Book

S686 ESTRO 36 2017 _______________________________________________________________________________________________

5 Saitama Medical University International Medical Center, Radiation Oncology, Saitama, Japan

and on the present disease were limited by tolerance of health tissues, especially by small bowel. The possibility of dose escalation (DE) was achieved by intracavitary brachytherapy (BRT) boost, the most classical and proven hypofractionation technique. More modern technologies and techniques, like Helical Thomoterapy (HT), allowed a safe and concomitant dose escalation in this setting of patients (pts) and we need to show our experience in terms of outcome, tolerance and feasibility Material and Methods From 2011 to 2015 we treated 34 pts affected by SCC, 22 with curative intent (4 recurrences). The mean age was 58 years (range 32-88). Grading was: G2 in 10 pts and G3 in 12pts. Stage was: IIA in 4 pts, IIB in 14 pts, IIIA in pt, IIIB I in 2 pts and IV in 1 pt. All pts received concurrent chemotherapy (CHT) with cisplatin and/or taxanes. All patients were treated with Intensity Modulated Radiation Therapy with Simultaneous Integrated Boost Image Guided Radiation Therapy (IMRT-SIB-IGRT) using @Helical Tomotherapy (HT). External beam radiotherapy (EBRT) was planned on PET-CT images acquired in treatment position. Tumor doses ranged from 60 to 70.4 Gy in 30 fractions (fr) with a moderate hypofractionation; dose to the pelvis ranged from 50.4 to 54 Gy. Lumbar-aortic chain was treated In 4 pts (51 Gy); 13 pts received a boost on PET positive lymph nodes with dose ranging from 60 to 66 Gy. All pts were treated with high dose rate BRT boost with dose/fraction of 6-15 Gy in 1-3 fr Results All pts completed the treatment. Mean follow up was 13,6 months (range 1-26). Three pts recurred: 1 pt in lumbar- aortic chain, 2 pts in pelvic region. Mean time to progression was 3,3 months. Overall survival was 82% with a mean time of 10 months. Two pts died for distant metastases, two for peritoneal progression. No acute or late gastro-intestinal (GI) toxicity > G2 were observed; only one pt developed a G3 acute and late genitourinary toxicity. No severe late hematological toxicity was observed; only one pt developed a G4 acute neutropenia requiring medical therapy Conclusion Our experience of double DE by HDR+ EBRT with concurrent chemotherapy, showed to be effective and safe and well tolerate with a low rate of complications EP-1291 Does concomitant boost using conformal therapy maximize local control in Stage III.B cervical cancer R. Santosham 1 1 Cancer Institute WIA, radiation oncology, Chennai, India Purpose or Objective BACKGROUND : This is a prospective study to assess the local control and toxicity profile of concomitant boost using conformal therapy. The role of IMRT to simultaneously boost the primary is unquestionable when small volumes are considered and where more organs are at risk around our target. But in an advanced pelvic malignancy where the target volume is large and where completely avoiding the bladder base or the recto-sigmoid septum are not recommended, 3D CRT may be tried. AIM : To compare the local control and acute toxicity profile of patients treated with concomitant boost and conventional fractionated radiotherapy. Material and Methods 29 patients with locally advanced FIGO stage III.B received concomitant boost(Arm A) (190cGy to the pelvis along with 210cGy to the boost volume) using conformal therapy between Sept 2015 and June 2016 of whom 18 patients received chemotherapy. In the same period, an age matched control group(Arm B) of 29 patients were managed with conventional fractionated radiotherapy of whom 11 patients received chemotherapy. All patients in the concomitant boost arm underwent repeat CT and replan at 36Gy when the response was assessed based on

Purpose or Objective Elderly patients with cervical cancer (CC) are commonly treated with radiation therapy (RT) alone because age- related physiologic changes can increase the toxicity of chemotherapy. Thus, brachytherapy (BT) assumes more crucial role for elderly patients with CC. In our institution, treatment technique of BT has moved from 2D-based to CT-based image guided BT (IGBT) in a phased manner. The purpose of this study is to analyze the impact of fraction of IGBT on the clinical outcome for elderly patients with CC. Material and Methods Between January 2001 and September 2014, 104 patients aged ≧ 70 years with CC received external beam RT (EBRT) and high-dose rate BT with curative intent in our institution. EBRT (38.0-56.8 Gy) with central shielding after 20-40 Gy was performed for each patient. We compared clinical results of two groups; the patients treated with IGBT only once (single-IGBT group, n=74) or at least twice (multiple-IGBT group, n=30) out of all sessions of BT. Four fractions of BT were administered once a week with a fraction dose of 6 Gy to Point A,basically. Dose adaptation was initially based on dose changes at Point A in IGBT session. If dose adaptation to Point A could not be achieved as intended, manual optimization of dwell positions and dwell weights was performed to improve dosimetry. We predicted that a 6 Gy isodose line would cover the high-risk clinical target volume (HR CTV) in order to achieve a HR CTV D90 (the minimum dose delivered to 90% of the HR CTV) of >6 Gy. The local control (LC) rate, overall survival (OS) rates, and late toxicities were compared in the 2 groups. Late toxicity was defined using the Radiation Therapy Oncology Group late radiation morbidity scoring system as any toxicity occurring 6 months after the initiation of RT. Results The median follow-up period was 59 months in all patients. Twenty-seven patients had stage IB, 45 had stage II, 29 had stage III, and 3 had stage IVA in FIGO staging. The median dose of all BT sessions in total was 24 (7.8-31) Gy at Point A. There was no statistical difference between the two groups in age, FIGO stage, tumor size, Point A dose, and the number of BT. The 4-year LC and OS rates were 89.5% and 70.2% in single-IGBT group, 87.5% and 59.0% in multiple-IGBT group, respectively. There were no statistical differences in survivals between the 2 groups. In regard to late toxicities ( ≧ grade 1), 18 patients developed lower gastrointestinal (GI) toxicity and 19 patients developed genitourinary (GU) toxicity in single- IGBT group, whereas 4 patients developed GI toxicity and no GU toxicity were found in multiple-IGBT group. Multiple-IGBT had tendency to reduce GI toxicity and significantly reduced GU toxicity (p < 0.05). Conclusion IGBT for elderly patients were performed safely and effectively. Multiple-IGBT, acquiring CT images more than twice, contributes to reduce late toxicity, compared to single-IGBT for elderly patients with CC. EP-1290 Helical Tomotherapy plus Brachytherapy boost in cervical cancer: a double dose escalation G. Cattari 1 , E. Delmastro 1 , A. Mranti 2 , S. Bresciani 2 , S. Squintu 1 , E. Garibaldi 1 , P. Gabriele 1 1 FPO-IRCCS Candiolo, Radiotherapy, Candiolo- Turin, Italy 2 FPO-IRCCS Candiolo, Medical Physic, Candiolo- Turin, Italy Purpose or Objective Traditionally, curative radiation treatment for squamous cervical cancer (SCC) is associated to concomitant chemotherapy platinum based. Doses on the pelvic volume