A randomized trial of patients older than 18 years with colorectal cancer treated by surgery , with resectable metastases based on CT scans of the chest , abdomen , and pelvis within the previous 30 days , and with a clear colonoscopy within the previous 18 months was conducted between 2005 and 2013 , involving 21 surgeons at 9 hospitals in Ontario , Canada , with PET-CT scanners at 5 academic institutions .