The PulMiCC trial is a randomized controlled trial testing the effect on survival of pulmonary metastasectomy in patients with colorectal cancer. In stage 1 of the trial patients with treated primary colorectal cancer metastatic to the lungs are invited to consent for protocol-based evaluation of their suitability for metastasectomy. The evaluation is as in current practice and includes PET/CT. A decision for or against metastasectomy may be based on the opinion of the clinicians and the preference of the patient. If there is uncertainty the patient is invited to consent to have the treatment arm assigned by randomization in stage 2 of PulMiCC. More than 300 patients have entered stage 1 and more than 70 are in stage 2.