BACKGROUND: Resection of colorectal hepatic metastases is an accepted treatment modality for stage IV colorectal cancer. Concurrent or sequential pulmonary metastasectomy continues to be a controversial strategy. We analyzed factors that predicted pulmonary recurrence in patients with resected hepatic metastases and examined the efficacy of these combined interventions in the treatment of metastatic colorectal cancer. METHODS: A retrospective review of a database of patients who underwent resection of colorectal hepatic metastases was performed to identify patients who either had synchronous pulmonary metastases (defined as pulmonary recurrence at the time of or within 3 months of hepatic metastasectomy) or subsequently experienced pulmonary metastases. Patient demographics, operative interventions, and overall survival were analyzed. Statistical methods included unpaired Student's t-test, actuarial survival and log-rank analysis. RESULTS: Twenty-one patients (19%) had pulmonary metastases after hepatic resection, of which 12/21(57%) underwent pulmonary resection. No differences were observed between the resection group, the nine patients with pulmonary metastases who did not undergo resection, and the 87 patients without pulmonary metastases with regard to age, sex, race, or extent of hepatic metastases. When comparing the resected versus the unresected pulmonary recurrences, the disease-free interval from hepatic resection to detection of pulmonary metastases was 21 +/- 20 months (range, 3-72 months) versus 16 +/- 8 months (range, 4-25 months), respectively. All patients with pulmonary recurrence who underwent pulmonary metastasectomy had unilateral disease. Seven of 12 (58%) underwent wedge/segmental resections, and the remaining five (42%) required lobectomy in order to obtain a complete resection. Four patients who underwent pulmonary resection had multiple lung metastases (two to four lesions), and eight had isolated metastasis. There were no perioperative deaths in the pulmonary metastasectomy group. Contraindications to pulmonary resection included extensive pulmonary disease and concurrent extrapulmonary disease. A survival benefit was noted at 3 years for the resected versus the unresected group (60% vs 31%). Survival was no different between the resected pulmonary recurrence patients and the resected hepatic metastases only patients (60% vs 54%). CONCLUSIONS: Pulmonary metastasectomy can be performed safely and effectively in patients with recurrent disease after hepatic resection for colorectal metastases. Prolonged survival can be achieved with resection of isolated pulmonary recurrence after hepatic resection for colorectal cancer. Further studies that delineate selection criteria for pulmonary resection of colorectal metastases are warranted.