Prediction of prognosis and surgical indications for pulmonary metastasectomy from colorectal cancer

Background. Treatment of pulmonary metastases from colorectal cancer by excision has increased rapidly, but reports on indications and prognostic factors are inconsistent. We sought to identify poor prognostic factors preoperatively and to retrospectively evaluate preoperative clinical indications for surgery. Methods. A total of 75 patients with colorectal cancer had pulmonary metastases excised from 1986 to 2003. Tumor size, number, laterality, hilar or mediastinal lymphadenopathy, and carcinoembryonic antigen level were possible risk factors for metastatic tumors, with primary site of colorectal tumor, disease-free interval, and hepatectomy for liver metastasis possible risk factors for primary tumors. Prognostic factors in univariate and multivariate analyses also included age and sex. Results. Five-year survival rates were 41.3% after pulmonary excision and 73.1% after primary colorectal resection. Three factors identified as significant by univariate log-rank test for overall survival after pulmonary resection were carcinoembryonic antigen (p < 0.0001), tumor laterality (p = 0.0205), and number of pulmonary metastases (p = 0.0028). Multivariate analysis found that carcinoembryonic antigen, tumor number, tumor size, and patient's age were also independent prognostic factors. In contrast, carcinoembryonic antigen, number of metastases, and disease-free interval predicted prognosis after primary colorectal resection. Prior hepatectomy for metastases did not influence prognosis after pulmonary metastasectomy. Conclusions. Elevated carcinoembryonic antigen level and multiple metastases are preoperative predictors of poor prognosis after resection of pulmonary metastases from colorectal cancer. Survival rate is sufficient to justify pulmonary metastasectomy if there is no local or distant metastatic lesion other than in the liver; if needed, sequential pulmonary and hepatic metastasectomy can be performed.