 Colorectal cancer CRC is the second leading cause of cancer deaths in the United States. About 90 of CRC related deaths are due to metastatic spreadmostly to the liver and lungs. With adequate multidisciplinary patient selection, CRC liver and lung metastasectomy significantly improves survival and offers the best chance for a cure. However, patients with limited lung or liver metastases are clinically underserved and poorly scientifically studied. The individual indication for resection and the decision making for adjuvant systemic therapies remains a challenge. More sensitive techniques to detect occult disease are needed for metastatic CRC mCRC patients, and perioperative analysis of circulating tumor cells CTCs may provide an outstanding opportunity to develop such innovative methods. We hypothesize that CTCs are enriched during CRC liver andor lung metastasectomy, and that they can be isolated and characterized in an attempt to identify novel therapeutic targets. 