Docetaxel, oxaliplatin, and fluorouracil/leucovorin (FLOT) versus epirubicin, cisplatin, and fluorouracil or capecitabine (ECF/ECX) as perioperative treatment of resectable gastric or gastro-esophageal junction adenocarcinoma: The multicenter, randomized phase 3 FLOT4 trial (German Gastric Group at