MR-guided Adaptive Stereotactic Radiotherapy for Endometrial Cancer

Rationale: External beam radiotherapy (EBRT) is an important cornerstone in treatment to reduce locoregional relapse in high(-intermediate) risk endometrial cancer (EC) patients. MR-guided adaptive radiotherapy (MGART) allows for more accurate delivery of radiation beams to the patients by visualizing and correcting for interfraction motion, with subsequent reduction of safety margins around the radiotherapy plan. Objective: The MASTEC study will investigate the safety of hypofractionated MR-guided adaptive radiotherapy in five fractions for elective pelvic nodal and vaginal vault irradiation in endometrial cancer.

Study design: Phase II multicentre intervention study Study population: Patients with endometrial cancer that receive adjuvant EBRT to the pelvic nodal areas and vaginal vault (with or without vaginal brachytherapy).

Intervention (if applicable): MR-guided adaptive radiotherapy (MGART) with reduced PTV margins, including 5 times 6Gy to the vaginal vault and pelvic nodal areas, 2 times a week .

Main study parameters/endpoints: The primary endpoint is acute gastrointestinal and genitourinary toxicity, scored by the Common Terminology Criteria Adverse Events version 6.0. Secondary endpoints are late gastrointestinal and genitourinary toxicity, quality of life and disease free survival; disease-specific survival; overall survival and metastasis-free survival.