Preoperative probability model for predicting overall survival after resection of pulmonary metastases from colorectal cancer

Background: The aim of this study was identify readily available factors most helpful in predicting survival and to develop a prognostic nomogram for patients with pulmonary metastases from colorectal cancer who are candidates for thoracotomy. Methods: Pretreatment data on 313 patients with metastases who underwent thoracotomy were analysed. Fourteen preoperative clinical and pathological variables were used to develop a probability model, in which their association with 3-year survival was tested. A nomogram to predict median, 1- and 3-year survival was constructed and validated internally using the concordance index (c-index). The nomogram was then validated with an external data set. Results: Five variables were identified as independent predictors of 3-year survival: prethoracotomy carcinoembryonic antigen level, number of pulmonary tumours, presence of hilar or mediastinal tumour-infiltrated lymph nodes, histology of the primary turnout and presence of extrathoracic disease. The nomogram was well calibrated for predicting 3-year overall survival. The internal validated c-index of the nomogram was 0.72. Applied to another data set, the external validated c-index was 0.66. Conclusion: This model has moderate predictive ability to discriminate between patients who arc likely to survive after thoracotomy for pulmonary metastases from colorectal cancer.