Objective: The main objective of this study is to determine the maximum tolerated dose (MTD) of 5 fractions MRgRT for patients with AC following FLOT therapy. The secondary objectives are feasibility, non-dose limiting toxicity, oncological outcomes and to explore variables for early response evaluation. Study design: 6+3 dose-escalation design with 4 radiotherapy dose levels. Study population: Patients with a resectable esophageal adenocarcinoma who are eligible for nCRT and surgery and who are eligible for MRgRT. Intervention: 5 sequential, homogenous fractions of 4-8 Gy within 2 weeks on the gross tumor volume (GTV) following preoperative FLOT (as part of standard perioperative chemotherapy) using MR-guided online adaptive radiotherapy on the MR-linac. Start in dose level 0, of 5 x 5Gy per patient, and if safe this is increased step-wise to a maximum dose level 3 of 5 x 8Gy per patient. Main study parameters/endpoints: The primary endpoint is the incidence of a dose limiting toxicity (DLT). Early DLT is defined as radiation induced esophageal fistula/ perforation/ hemorrhage/ necrosis or tracheal, bronchial or bronchopleural fistula/tracheal or bronchopulmonary hemorrhage grade ≥ 3 or any non-hematological grade ≥ toxicity, assessed clinically significant and related to the radiotherapy, according to Common Toxicity Criteria for Adverse Events (CTCAE) version 5.0 occurring within 16 weeks after the start of radiotherapy and before surgery or postponing of surgery \> 16 weeks after the end of radiotherapy due to any grade of treatment-related toxicity. Subacute DLT is defined as peri- and/or postoperative complications occurring within 30 days after surgery, defined as postoperative anastomotic leakage or pneumonitis ≥ 3b according to Clavien-Dindo. Secondary endpoints are non-DLT toxicity, the technical feasibility of dose delivery, perioperative complications. and oncological outcomes including R0 resection rate, histopathological tumor response, local and regional recurrence and death from any cause. Nature and extent of the burden and risks associated with participation, benefit and group relatedness: The benefits for the patients may include higher probability of complete primary tumor and lymph node metastases response that initially lead to increased survival and could eventually result in organ-sparing treatment programs. Possible risks are mainly esophageal fistula/perforation and broncho-esophageal fistula or hemorrhage.