Kanemitsu et al. [23] devised a model to predict the prognosis of patients after resection of pulmonary metastases from CRC, which included preoperative carcinoembryonic antigen (CEA) level, number of pulmonary tumors, etc. The internal validated concordance index (C-index, equivalent to AUC) of this model reached 0.72, but the external validated C-index was only 0.66, suggesting this model has only moderate predictive power. Here, CEACAM5 is linked to colorectal carcinoma.