Pulmonary Metastases

The lungs are among the most common sites for distant metastases, especially in the setting of colorectal cancer, breast cancer, kidney cancer, head and neck cancers, melanoma, testicular cancers, and bone and soft tissue sarcomas.

Clinical FeaturesTop

Small metastases are asymptomatic; as the disease progresses, chest pain, shortness of breath, and hemoptysis may occur due to tumor growth or complications (bronchial obstruction, atelectasis, pneumonia, local invasion).

DiagnosisTop

Computed tomography (CT) of the chest is the primary diagnostic method to establish the presence of lung metastases. The radiologic picture varies and may include single or multiple round nodules, generalized changes of lymphangitic carcinomatosis, areas of atelectasis, enlargement of the hilar or mediastinal lymph nodes, and/or pleural effusion. In most cases, the radiologic image in conjunction with diagnosis of a malignancy of another organ is sufficient to diagnose metastases without the need for histologic verification. In unclear cases biopsy (percutaneous or transbronchial) may be necessary.

Differential Diagnosis

Primary lung cancer (including lung cancer metastases or multiple primary lung malignancies), benign tumors, tuberculosis, lung abscess, fungal lesions, teratoma, hamartoma, vasculitis.

TreatmentTop

In patients with multiple lung metastases and in tumors with high chemosensitivity, chemotherapy typically used in the treatment of a specific tumor can be administered; in some malignancies such as lymphoma, choriocarcinoma, and testicular cancer, excellent results can be achieved. The role of molecularly targeted drugs, administered in a highly specialized setting, is growing rapidly: the drug is selected depending on the type of primary tumor and tumor predictive features (eg anti–human epidermal growth factor receptor 2 [HER2] drugs in HER2-positive breast cancer; mTOR kinase inhibitors in, among others, kidney cancer; BRAF and MEK inhibitors in melanoma, lung cancer, epidermal growth factor [EGFR] inhibitors in lung cancer). The role of palliative intent treatment with immune checkpoint inhibitors is also growing.

Surgical wedge resection of a limited number of metastases with a margin of healthy lung parenchyma may be justified in a small number of carefully selected patients. Such an aggressive approach is reserved for certain cases when there are fewer metastases, longer disease-free intervals between primary tumor treatment and metastases detection, absence of primary tumor recurrence, and absence of additional extrathoracic metastatic spread. Radiotherapy is a method of palliative treatment of patients with bleeding, shortness of breath, or pain due to lung metastases. In the case of a limited number of metastases, stereotactic radiotherapy is an alternative to surgery. Brachytherapy, a form of high-dose localized radiotherapy delivered endobronchially, is reserved for selected situations in which endobronchial metastatic invasion is causing either shortness of breath due to airway obstruction or hemoptysis.