Colchicine is an inexpensive drug and a highly effective anti-inflammatory agent that holds great potential for preventing POAF in patients undergoing thoracic surgery. Data from cardiac surgery patients suggest that prevention of POAF using colchicine is feasible, but whether this concept is also applicable to patients undergoing thoracic surgery, where the risk of POAF is lower and underlying mechanisms may be different, is currently unclear. The 'Colchicine for the prevention of perioperative AF' (COP-AF) trial has been designed as a large randomized, double blind, placebo controlled trial to determine whether colchicine, a potent, safe and inexpensive anti-inflammatory drug, lowers the risk of perioperative AF and other inflammatory complications in patients undergoing thoracic surgery. The primary objective of this trial is to determine whether a 10-day course of colchicine 0.5mg twice daily reduces the incidence of perioperative AF within 14 days after thoracic surgery.