Lung Metastases
Lung metastases occur when cancer cells from another part of the body spread (metastasize) to the lungs. Because the lungs receive the entire body’s blood flow, they are one of the most common sites where metastatic cancer cells can settle and grow. Lung metastases may appear as small nodules, larger masses, or multiple spots scattered throughout the lungs, and are often discovered during imaging performed for cancer staging or follow-up.
What is it?
Lung metastases occur when cancer cells travel from a primary tumor elsewhere in the body—such as the breast, colon, kidney, or skin—and implant within the lung tissue. These cells can form one or multiple nodules or masses, which may vary in size and appearance depending on the original cancer. Because metastatic disease reflects cancer spreading beyond its original site, finding lung metastases can help guide staging, treatment planning, and prognosis.
Radiologists evaluate features such as the number of lesions, their size, growth over time, and their pattern of spread. Some cancers present with a few well-defined nodules, while others create diffuse involvement or spread along the lymphatic vessels within the lungs. Comparison with prior imaging is essential to assess progression and response to treatment.
Important to Know
Lung metastases are not the same as primary lung cancer. Treatment is determined by the type of cancer that originally developed elsewhere in the body, not by the appearance of the lung lesions themselves. Many patients have no symptoms, especially when the metastatic nodules are small or few in number. As lesions grow, symptoms may include persistent cough, chest pain, difficulty breathing, or coughing up blood.
CT imaging is the most sensitive method for detecting lung metastases, and PET/CT may help determine how active or widespread the disease is. Red flags that warrant immediate evaluation include sudden or worsening shortness of breath, coughing up significant blood, unexplained weight loss, or rapidly increasing chest pain. Management typically involves systemic therapy coordinated by an oncology team, and follow-up imaging is used to monitor treatment response.