International audienceObjective: To answer whether synchronous colorectal cancer liver metastases (SLM) should be resected simultaneously with primary cancer or should be delayed. Summary Background Data: Numerous studies have compared both strategies. All were retrospective and conclusions were contradictory. Methods: Adults with colorectal cancer and resectable SLM were randomly assigned to either simultaneous or delayed resection of the metastases. The primary outcome was the rate of major complications within 60 days following surgery. Secondary outcomes included overall and disease-free survival. Results: A total of 105 patients were recruited. Eighty-five patients (39 and 46 in the simultaneous- and delayed-resection groups, respectiv...