ESTRO 38 Abstract book

S807 ESTRO 38

EP-1490 Bone mineral density correlates to pelvic fractures after radiotherapy for cervical cancer D. Kurrumeli 1 , B. Weidenbächer 1 , K. Borm 1 , M. Oechsner 1 , S.E. Combs 1 , C. Brams 2 , M. Löffler 3 , M.N. Duma 1 1 Klinikum rechts der Isar- TU München, Department of Radiation Oncology, München, Germany ; 2 Klinikum rechts der Isar- TU München, Department of Gynaecology, München, Germany ; 3 Klinikum rechts der Isar- TU München, Department of Neuroradiology, München, Germany Purpose or Objective The aim of this study was to investigate the risk factors for pelvic insufficiency fractures (PIF) after radiotherapy for cervical cancer. Material and Methods Medical records and imaging studies, including CT and MRI of 62 women with cervical cancer who received definitive or adjuvant radio(chemo)therapy between 2013 and 2017 were reviewed. 33 patients were treated with definitive radiochemotherapy, 22 with adjuvant radiochemotherapy and 7 patients were treated with radiotherapy alone. All patients received pelvic MRI during follow-up. The PIF were detected in the follow-up MRI. For each patient we manually contoured the sacrum and analyzed the bone mineral density (BMD) [mg/cm 3 ] according to Schwaiger BJ, et al. AJNR Am J Neuroradiol 2014;35:1628–33. The BMD predicts osteoporotic vertebral fractures. We then registered the MRI of the PIF patients to the planning CT and contoured the PIF . Then, on the contralateral side of the fracture , a mirrored structure of the fracture was generated (mPIF). For the sacral bone as well as the fractures we analyzed the BMD, V50Gy, Dmean and Dmax. We also analyzed the BMD of three lumbar spine vertebral bodies (between the 1st and 5th) as well as the S1 and S2 sacral vertebrae for each patient. Results Out of 62 patients, 6 (9,7%) had a fracture. All of them were insufficiency fractures and all of them in the massa lateralis of the sacral bone. Two out of the 6 patients had a bilateral fracture with only one of them being symptomatic. PIF patients showed a significantly lower BMD in the sacral bone (p<0.026) as well as in the lumbar vertebrae (p<0.05). The BMD of the PIF was 70,4mg/cm³ and of the mPIF on the contralateral side was 84,2mg/cm³. However, the difference in the PIF compared to the mPIF was not significant (p<0.49). The Dmean/Dmax of the sacrum in the PIF group was 40,3 Gy/55,4 Gy and in the other patients- i.e. without PIF-(OTH) 39,7Gy/53,9Gy, respectively (with no significant difference between groups). Similarly, the V50Gy of the sacrum in the PIF group compared to OTH as well as the V50Gy of the PIF compared to the mPIF did not reach significance (p<0.43 and p<0.12 respectively). Conclusion PIF were detected in 9,7% of the patients. The dose does not seem to have a relevant impact on the incidence of PIF in our patients. One of the predisposing factors for developing PIF after radiotherapy seems to be the BMD which was significantly lower in the PIF group. For these patients preventive measures to improve BMD should be taken into account. EP-1491 Clinical outcome and toxicity of MRI-based vaginal cuff brachytherapy in endometrial cancer C. Jaisawang 1 , P. Alisanant 1 , K. Shotelersuk 1 , C. Khorprasert 1 , N. Amornwichet 1 1 King Chulalongkorn Memorial Hospital, Division of Radiation Oncology- Department of Radiology, Bangkok, Thailand Purpose or Objective In the 3-dimensional image-guided brachytherapy era, the determination of vaginal thickness can be optimized for

to that of previously published randomized studies. Our results confirm that MIS using robotic arm combined with adjuvant RT, especially VBT, should be offered for patients with stage I intermediate-risk endometrial cancer. EP-1489 How effective is adjuvant radiotherapy in the management of stage I high-risk endometrial cancer? J. Song 1 , T. Le 2 , M. Gaudet 1 , C. Ee 1 , K. Lupe 1 , R. Samant 1 1 The Ottawa Hospital, Radiation Oncology, Ottawa, Canada ; 2 The Ottawa Hospital, Gynecologic Oncology, Ottawa, Canada Purpose or Objective A recent randomized controlled trial (PORTEC-3) has demonstrated that in endometrial cancer patients with high-risk features, compared to radiotherapy alone, addition of chemotherapy to radiotherapy results in a significant improvement on failure-free survival. However, in the study, the effect of chemotherapy was limited to stage III patients, while the benefit was less pronounced in stage I and II patients. Our study aims to investigate clinical outcome in stage I high-risk endometrial cancer patients who received radiotherapy only, and compare patient outcomes to those from the previous literature. Material and Methods A single-center retrospective study was conducted on women with high-risk endometrial cancer with FIGO 2009 stage I, endometrioid-type grade 3 with deep myometrial invasion or lymph-vascular space invasion, or both, who have undergone hysterectomy at our institution between 1998 and 2015. Data on surgical and radiation treatments, as well as patient and tumor characteristics were collected and correlated with clinical outcomes. Statistical analysis was carried out using Kaplan-Meier method to compare clinical outcomes to previously reported studies. Results A total of 46 stage I high-risk endometrial cancer patients were identified. Median age at diagnosis was 63 years (range 49-86 years) and median follow-up was 4.2 years. All patients underwent total abdominal hysterectomy and bilateral salpingo-oophorectomy (TAH-BSO). Surgical staging was performed with pelvic lymph node dissection on 38 (82.6%) patients, while 35 (76.1%) and 11 (23.9%) patients underwent minimally invasive surgery (MIS) and traditional laparotomy, respectively. Thirty-four (80.4%) patients underwent adjuvant radiotherapy alone (31 patients with external beam radiotherapy, EBRT, 45Gy in 25 fractions; and 3 patients with vaginal brachytherapy, 30Gy in 3 fractions), two (4.3%) patients underwent combined chemoradiotherapy (chemotherapy with 6 cycles of intravenous carboplatin and paclitaxel; radiotherapy with EBRT), and 9 (19.6%) patients received no adjuvant treatment. Five-year disease-free survival and overall survival rates were 74.2% and 80.2%, respectively. Five-year disease-specific mortality rate was 14.1%. Among 9 patients with recurrent disease, most disease relapse (89.9%) occurred outside pelvis in 8 patients, while only one patient had regional recurrence (perirectal lymph node). Five-year loco-regional relapse- free survival was 97.8%. Conclusion Clinical outcomes for stage I endometrial cancer patients with high-risk features in our study are consistent with the published literature. Adjuvant radiotherapy results in high rates of loco-regional disease control, and most recurrences occurred at distant sites. Systemic treatment with chemotherapy may be indicated in stage I endometrial cancer patients with high-risk features to further reduce the risk of distant relapses and improve survival.