Gynecological Cancer

PD 15 - GYN 2 - Poster Discussion

1129 - Dose and Volume Parameters for MRI-Guided Cervix Cancer Brachytherapy in the Embrace Trial

Wednesday, October 24
11:18 AM - 11:24 AM
Location: Room 217 A/B

Dose and Volume Parameters for MRI-Guided Cervix Cancer Brachytherapy in the Embrace Trial
N. Nesvacil1,2, R. Potter1, K. Tanderup3, I. Dumas4, J. Swamidas5, A. De Leeuw6, R. Hudej7, G. Lowe8, S. Spampinato3, J. Lindegaard3, I. Jurgenliemk-Schulz9, and C. Kirisits1,2; 1Department for Radiation Oncology, Comprehensive Cancer Center, Medical University of Vienna, Vienna, Austria, 2Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Medical University of Vienna, Vienna, Austria, 3Department of Oncology, Aarhus University Hospital, Aarhus, Denmark, 4Department of Radiotherapy, Gustave-Roussy, Villejuif, France, 5Tata Memorial Hospital, Mumbai, India, 6Department of Radiation Oncology, University Medical Centre Utrecht, Utrecht, Netherlands, 7Department of Radiotherapy, Institute of Oncology Ljubljana, Ljubljana, Slovenia, 8Mount Vernon Cancer Centre, London, United Kingdom, 9University Medical Center Utrecht, Utrecht, Netherlands

Purpose/Objective(s): The intErnational study on MRI-guided BRachytherapy in locally Advanced CErvical cancer (EMBRACE, www.embracestudy.dk) is a prospective observational study of treatment and clinical outcome data of 1416 patients with locally advanced cervical cancer from 23 centers, who were treated with radiochemotherapy (EBRT and image-guided brachytherapy (IGBT), between 2008 and 2016. EMBRACE data reflect the implementation of MRI-based IGBT through a variety of institutional protocols. The aim of this analysis was to report on the overall status of the implementation of this technique and to analyse dose-volume parameters according to GEC ESTRO recommendations.

Materials/Methods: 1300 patients with complete treatment data records were included in this analysis. The distribution of implant types (intracavitary [ic] or intracavitary/interstitial [ic/is]), and dose rate schedules (high/pulsed dose rate [HDR/PDR]) was analysed. Total treatment doses including EBRT and IGBT were converted to biologically equieffective dose in 2Gy fractions (EQD2) using the linear quadratic model, and dose reporting parameters for high-risk CTV (CTVHR) and organs at risk according to ICRU89 and GEC-ESTRO recommendations. A subgroup analysis was performed for different target volumes.

Results: Almost all patients were treated with EBRT of 45-50.4 Gy to the elective PTV, with 3D conformal (58%) or IMRT (42%) techniques. HDR BT (57%) was delivered mostly in 3 (20%), 4 (73%) or 5 (7%) fractions; PDR BT (42%) in 1 or 2 fractions (50%/50%). Most BT treatments were delivered with ring applicators (58%), followed by ovoids (27%), vaginal moulds (12%) or cylinders (1%). IC applicators were exclusively used in 56% of patients, 44% were treated with ic/is only, or a combination of techniques. In ic/is implants the mean number of active needles per patient was 4.1±2.8. The mean overall treatment time for EBRT (including any sequential nodal boosts) and BT was 46.5±6.5 days. BT was administered after delivery of at least 45Gy of EBRT in 58% of patients, while 39% of BT treatments started after 30-45 Gy EBRT. The FIGO stage distribution was 19% 1B, 5% 2A, 52% 2B, 1% 3A, 15% 3B, 3% 4A, and 5% 4B. The median CTVHR volume was 28.7 cm³ (mean 34.5±21.5 cm³). The mean CTVHR D90 was 89.7±8.8 Gy EQD210. For ic treatments the mean point A dose was 74.1±7.6 Gy EQD210. For ic and ic/is groups, with mean CTVHR volumes of 26.5 and 44.8 cm³, the mean CTVHR D90 were 90.5/88.7 Gy EQD210. Overall, for CTVHR volumes 30cm³, the mean D90 was 92.5/86.5 Gy EQD210, mean D2cm³ was 73.8/79.4 for bladder, and 61.1/64.3 Gy EQD23 for rectum. In total 76% of all patients received a CTVHR D90>85 Gy EQD210, 92% had a bladder D2cm³ <90 Gy EQD3, and 95% had a rectum D2cm³ <75Gy EQD3.

Conclusion: The prospective EMBRACEII protocol will further promote the implementation of IGBT with ic/is technique. Further improvement of target coverage and organ sparing is expected.

Author Disclosure: N. Nesvacil: None. R. Potter: Research Grant; Varian Medical, Nucletron, an Elekta Company. Radiotherapy and Oncology; Elsevier. ESTRO; ESTRO. Comprehensive Cancer Center (CCC); Medical University of Vienna. Medical University of Vienna & EBG MedAustron; Medical University of Vienna & EBG MedAustron. K. Tanderup: Research Grant; Nucletron - an Elekta company, Varian Medical Systems. Network Coordinator; GEC ESTRO Gyn Network. I. Dumas: None. G. Lowe: None. S. Spampinato: None. I. Jurgenliemk-Schulz: None. C. Kirisits: Research Grant; Elekta. Honoraria; Elekta. Travel Expenses; Elekta. chairman; GEC ESTRO.

Nicole Nesvacil, DSc

Disclosure:
No relationships to disclose.

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