CEACAM5 and colorectal carcinoma: Several clinical factors, including a short disease‐free interval between the diagnosis of primary tumor and onset of lung metastases, multiple lung metastases (two or more), mediastinal and hilar lymph node involvement and elevated prethoracotomy serum carcinoembryonic antigen (CEA) levels, have been associated with reduced survival after pulmonary metastasectomy in patients with CRC 5.