Lung cancer metastasis occurs when cancer cells detach from the primary tumor and travel through the bloodstream or lymphatic system to distant sites. According to Verywell Health, lung cancer often spreads to the lymph nodes, bones, brain, liver, and adrenal glands. Less common sites include: the stomach, intestines, pancreas, eyes, skin, kidneys, or chest.

The risk of metastasis depends on the disease stage and cancer type. Non-small cell lung cancer (NSCLC) is the most common type. According to the US National Cancer Institute (NCI), about 40% of NSCLC cases are diagnosed at stage 4, when metastasis has already occurred.

Lymph Nodes

Lymph nodes are small organs distributed throughout the body that trap and filter foreign substances. Lung cancer first spreads to lymph nodes within the lungs or near the main airways. This local invasion can occur in stage 2 NSCLC and is often asymptomatic.

Without treatment, the cancer can spread to distant lymph nodes and other parts of the body. At this stage, patients might notice a hard lump in the neck or armpit, where lymph nodes contain cancer cells.

Surgical removal of some or all nearby lymph nodes is the primary treatment for early-stage non-small cell lung cancer. Other methods, such as radiation therapy, chemotherapy, and targeted therapy, can be combined with surgery or used individually for patients with metastatic cancer.

Bones

One of the more serious complications of non-small cell lung cancer is metastasis to the bones. According to Healthline, the areas most affected by bone metastasis include: the spine, pelvis, femur, upper arm bones, hands, and feet.

Pain is the most common symptom, often starting gradually as a muscle strain or soreness, then becoming intense. More severe symptoms can occur, such as fractures in areas weakened by the disease, hypercalcemia, or spinal cord compression if the cancer spreads to the spine.

The main treatment goal at this stage is alleviating pain and preventing fractures, including: pain medication, radiation therapy, surgery, and drugs used to slow bone breakdown.

Common sites of lung cancer metastasis. Illustration created by AI.

Brain

According to the American Lung Association, this is the most common type of cancer to metastasize to the brain. Many patients are asymptomatic, while others may experience headaches, often accompanied by nausea or vomiting, confusion, memory loss, seizures, vision loss, or numbness or weakness on one side of the body.

Treatment at this stage primarily focuses on symptom control rather than a cure, including: pain medication, anticonvulsant medications, radiation therapy to shrink tumors, or steroids to reduce brain swelling. In cases of limited metastasis, doctors may consider surgery or radiation therapy.

Liver

Lung cancer metastasis to the liver can affect 30-50% of patients in advanced stages. Patients may experience loss of appetite, weight loss, fatigue, leg swelling, itching, or yellowing of the skin or eyes (jaundice). Chemotherapy is often used to treat both the primary tumor and cancer cells in the liver.

Adrenal Glands

The adrenal glands are organs located on top of the kidneys that produce hormones. Lung cancer metastasis to the adrenal glands is often asymptomatic. Patients typically receive chemotherapy to prolong survival or undergo surgery to remove both the lung tumor and the affected adrenal gland.

Most cases of metastatic lung cancer are incurable and often have a poor prognosis. According to the NCI, the 5-year survival rate for metastatic lung cancer is 6.3%.

Anh Ngoc (Compiled)