Irinotecan and retetrasse combined with radiotherapy with or without bevacizumab in patients with recurrent colorectal cancer: a multicenter, prospective, randomized controlled clinical trial

Interventions: control group:Irinotecan was given intravenously at week 1, week 3 and week 5, 180 mg / m2; Retetrasse was given intravenous drip of 2 mg / m2 for 1 day at 1, 3 and 5 weeks; Concurrent radiotherapy: IMRT external radiotherapy.;Experimental group:Irinotecan was given intravenously at week 1, week 3 and week 5, 180 mg / m2; Retetrasse was given intravenous drip of 2 mg / m2 for 1 day at 1, 3 and 5 weeks; Bevacizumab was given intravenously for 1 day at week 1, 3 and 5; Concurrent radiotherapy: IMRT external radiotherapy. Primary outcome(s): Objective response rate Study Design: Parallel