Introduction: Autopsy studies of persons who died of cancer have shown the lungs to be the sole site of metastasis in about 20% of cases. The resection of pulmonary metastases is indicated for palliative purposes if they contain a large volume of necrotic tumor, infiltrate the thoracic wall to produce pain, or cause hemoptysis or retention pneumonia. Metastasectomy with curative intent may be indicated for carefully selected patients.
Methods: This review is based on a selective search of the PubMed database for articles that were published from 2006 to 2011 and contained the keywords "pulmonary metastasectomy," "lung resection of metastasis," and "lung metastasectomy."
Results: No prospective comparative trials have been performed to date that might provide evidence for prolongation of survival by pulmonary metastasectomy; nor have there been any randiomized, controlled trials yielding evidence that would assist in the decision whether to treat pulmonary metastases with surgery, radiotherapy, or chemotherapy (or some combination of these). The indication for surgery is a function of the histology of the primary tumor, the number and location of metastases, the lung capacity that is expected to remain after surgery, and the opportunity for an R0 resection. Favorable prognostic factors include a long disease-free interval between the treatment of the primary tumor and the discovery of pulmonary metastases, the absence of thoracic lymph node metastases, and a small number of pulmonary metastases. The reported 5-year survival rates after pulmonary metastasectomy, depending on the primary tumor, are 35.5% to 47% for renal-cell carcinoma, 39.1% to 67.8% for colorectal cancer, 29% to 52% for soft-tissue sarcoma, 38% to 49.7% for osteosarcoma, and 79% to 94% for non-seminomatous germ-cell tumors. For the latter two types of tumor, chemotherapy is the most beneficial form of treatment for long-term survival.
Conclusion: When there is no good clinical alternative, the resection of pulmonary metastases can give some patients long-lasting freedom from malignant disease. Patients should be carefully selected on the basis of clinical staging with defined prognostic indicators.