The RACE trial seeks to demonstrate superiority of preoperative FLOT induction chemotherapy followed by preoperative radiochemotherapy and postoperative FLOT chemotherapy over perioperative FLOT chemotherapy without radiotherapy in patients with adenocarcinoma of the gastroesophageal junction undergoing adequate oncological surgery.

Eligible patients will be randomly allocated to one of two treatment groups, i.e. preoperative chemotherapy (Arm A) or preoperative chemotherapy with subsequent preoperative radiochemotherapy (arm B), both followed by resection and postoperative completion of chemotherapy. Randomization will occur in a 1:1 ratio with stratification by primary tumor site (Siewert I vs. Siewert II/III).

Arm A:

Patients randomized to Arm A (control arm) will be treated with four preoperative cycles of FLOT. Cycles will be repeated every two weeks. The preoperative chemotherapy duration in Arm A is eight weeks. Surgical resection will follow 4-6 weeks after day 1 of the last cycle of neoadjuvant therapy. Postoperative chemotherapy will start 6-12 weeks after surgery and consists of another four cycles of FLOT every two weeks. The total treatment period is 25-32 weeks.

Arm B:

Patients randomized in Arm B (experimental arm) will be treated with two cycles of FLOT every two weeks. Radiochemotherapy will start three weeks after day 1 of the second cycle and consists of oxaliplatin and infusional 5-fluorouracil plus concurrent radiotherapy given to a dose of 45 Gy (25 daily fractions with 1.8 Gy) over five weeks. The preoperative treatment duration is 10 weeks. Surgical resection will follow 4-6 weeks after last treatment with chemotherapy / radiation. Postoperative chemotherapy will start 6-12 weeks after surgery and consists of four cycles of FLOT every two weeks. The total treatment period is 26-33 weeks.