Lung Metastases
Summary of Key Points
Evaluation
• Few lung metastases are symptomatic; only 15% to 20% of patients report having a cough or pain. All patients with isolated pulmonary metastasis from an extrathoracic malignancy should be evaluated for the possibility of resection.
• Initial imaging studies should consist of a computed tomographic (CT) examination to predict resectability. Integrated fluorine-18 fluorodeoxyglucose positron emission tomography–CT may be substituted for CT alone. Magnetic resonance imaging has a limited role.
• CT is unable to distinguish reliably between malignant and benign lesions.
• CT differs from the final pathology report in 42% of cases.
• CT underestimates the number of malignant lesions in 25% to 35% of cases.
• The accuracy of radiologic imaging is only 37%, underestimating the number of lesions by 39% and overestimating them by 25%, for patients undergoing bilateral exploration.
• Prognostic factors include number of metastases, disease-free interval, and histology/organ site of the primary tumor.
Pulmonary Metastasis for Specific Tumor Types
• From 10% to 25% of patients with primary colorectal tumors have detectable metastases at the time of primary tumor diagnosis.
• Metastatic disease develops in 25% to 70% of patients with localized bone and soft tissue sarcoma; 10% will present with metastasis at the time of primary tumor diagnosis.
Isolated lung metastases occur in up to 20% of patients with sarcoma during the course of their disease, with the lung being the sole site of failure after treatment in up to 90% of cases.
• Patients with metastatic melanoma have an especially poor prognosis, with isolated lung metastasis occurring in 2% to 11% of patients.
• In 50% of patients who have a radical nephroureterectomy, pulmonary metastases later develop; however, only 16% have metastatic disease confined to the lung.
