In this open-label , multicentre , phase 2 , randomised trial , patients with postoperative pathological stage II ( ypT3-4N0 ) or III ( ypTanyN1-2 ) rectal cancer after preoperative fluoropyrimidine-based chemoradiotherapy and total mesorectal excision were recruited and randomly assigned ( 1:1 ) via a web-based software platform to receive adjuvant chemotherapy with either four cycles of fluorouracil and leucovorin ( fluorouracil 380 mg/m ( 2 ) and leucovorin 20 mg/m ( 2 ) on days 1-5 , every 4 weeks ) or eight cycles of FOLFOX ( oxaliplatin 85 mg/m ( 2 ) , leucovorin 200 mg/m ( 2 ) , and fluorouracil bolus 400 mg/m ( 2 ) on day 1 , and fluorouracil infusion 2400 mg/m ( 2 ) for 46 h , every 2 weeks ) .