ESTRO 2022 - Abstract Book

S1135

Abstract book

ESTRO 2022

Intracavitary brachytherapy is a fundamental treatment in the adjuvant treatment of endometrial cancer, reducing vaginal vault recurrences. The most common form of administration is HDR brachytherapy with Iridium-192 but electronic brachytherapy is proposed as an alternative. Our objective has been to evaluate the effectiveness and toxicities observed in the long term of electronic brachytherapy (eBQT) in the treatment of endometrial cancer. Materials and Methods Patients with endometrial cancer treated with intracavitary eBQT between October 2015 and September 2016 were retrospectively analyzed. eBQT was administered by cylindrical applicators with a dose of 15 Gy (5Gy/fraction) after previous external radiotherapy (EBRT) with a dose of 46 Gy (2Gy/fraction) and 25 Gy (5Gy/fraction) in those who underwent adjuvant exclusively. Their history, oncologic and dosimetric data, acute toxicities (<90 days) and late toxicities (>90 days) according to the CTCAE v.5 scale, recurrences and exits during follow-up were analyzed. Statistical analysis was performed with Student's t-test and Chi-square test. P values < 0.05 were considered statistically significant. Results Thirty-six patients with a mean age of 64.56 years were collected. Endometrioid carcinoma was diagnosed in 77.8%, serous carcinoma in 11.1%, carcinosarcoma in 5.6% and clear cell carcinoma in 5.6%. VILI was present in 33.3% and 58.3% had a depth of more than 50% of the myometrium. 22.2% were grade 1, 41.67% G2 and 36.11% G3 or poorly differentiated. 86.11% were classified as FIGO I-II. TEN was performed over the pelvis in 20 patients (56%). The diameters of the applicators used were 2.5, 3 and 3.5 in 8%, 42% and 50% respectively. The active length treated was 2.5 cm in 19% and 3 cm in 81%. 25 patients (69.4%) presented some type of acute toxicity: rectal toxicity 13, urinary toxicity 12 and on vaginal mucosa 13, with no G3 toxicity observed. 8 patients (22.2%) presented some type of late toxicity: urinary toxicity 1, rectal toxicity 4 and on vaginal mucosa 6, none of them G3. A statistically significant association was found between TEN and acute rectal toxicity (p= 0.008). With a follow-up of 67.48 months 9 patients have relapsed (25%). 7 patients at a distance, 1 through pelvic adenopathies and 1 in the lower third of the vagina (not irradiated). 6 patients have died, 4 of them due to their oncologic disease (11.11%). A statistically significant association was found between myometrial invasion greater than 50% and recurrence (p= 0.032) as well as exitus with oncologic history (p=0.038), histology type 1-2 (p=0.033) and FIGO stage (p= 0.010). Conclusion Electronic brachytherapy on vaginal vault in the adjuvant treatment of endometrial cancer is an effective technique with good tolerance. 1 Peking University Third Hospital, Department of Radiotherapy, Beijing, China; 2 Peking University Third Hospital , Department of Radiotherapy, Beijing, China; 3 Peking University Third Hospital , Department of Radiotherapy , Beijing, China Purpose or Objective In this study we aimed to assess the maximum-tolerated dose (MTD) of nab-paclitaxel (Keaili ® ) in combination with a fixed dose of cisplatin when given concurrently with radiotherapy to patients for locally advanced cervical cancer (LACC). Materials and Methods Chemotherapy: Patients firstly receive an escalating dose of weekly nab-paclitaxel starting at 10 mg/m 2 up to 70 mg/m 2 , Patients secondly receive weekly cisplatin (40 mg/m 2 ). Treatment repeats every week until the disease recurrence or unacceptable toxicity, death or begin a novel therapeutic. Concurrent chemotherapy is a weekly regimen during radiotherapy. Patients will complete at least 4 cycles of concurrent chemoradiotherapy, until the MTD appeared. Radiation therapy: Patients also receive pelvic radiation therapy once daily (Monday-Friday) for a total of 28 fractions and intracavitary brachytherapy twice a week for a total 5 fractions. Complete radiotherapy within 55 days. (ClinicalTrials.gov Identifier: NCT04017377) Results This study was initiated in September, 2019, and enrollment ended in October, 2021. Eighteen patients with stage Ⅰ B2- Ⅳ A cervical cancer were enrolled in this study. Five levels of nab-paclitaxel were studied with three, three, three, six and three patients enrolled, respectively. The MTD of nab-paclitaxel was found at 50 mg/m 2 /week. At level 4, 1 patient experienced DLT because of grade 3 right upper extremity edema. At level 5, two DLTs (grade 3 rash and grade 3 perineal edema) were observed in two patients. Other major side effects included leukopenia, neutropenia, hypochromia, fatigue and nausea. Sixteen patients were evaluable for response: two complete and fourteen partial responses were obtained with an overall response rate of 100%. Conclusion Based on the results obtained from this study, weekly administration of 50 mg/m 2 nab-paclitaxel when associated to cisplatin 40 mg/m 2 /week and concurrent radiotherapy can be considered a tolerable and safe dose for the treatment of locally advanced cervical cancer. PO-1340 Phase Ⅰ Trail of Concurrent Nab-paclitaxel and Cisplatin with VMAT for LACC P. Jiang 1 , A. Qu 2 , W. Jiang 2 , X. Deng 2 , J. Wang 3