Metastasis is the spread of cancer from its original location to other parts of the body. This is also called metastatic cancer, or in the case of lung cancer, metastatic lung cancer. Cancer can metastasize when cells from the original tumor break off and travel through the bloodstream or the lymphatic system to distant sites of the body. The lymphatic system is made up of vessels and lymph nodes that carry fluid and immune cells, also known as lymphocytes, throughout the body. Lung cancer often first spreads to lymph nodes in the lungs.1,2
Even after a cancer has metastasized to a new organ or part of the body, it is still named for its original location. For example, lung cancer that has spread to the brain is metastatic lung cancer – not brain cancer.1
Staging
The stage of lung cancer describes the extent of the disease and includes the size of the tumor, the involvement of lymph nodes, and the spread to distant areas of the body. The stage of a patient’s lung cancer helps doctors determine the best course of treatment. The staging system also provides a generalized picture of prognosis, or expected outcome. The presence of metastases means the cancer has reached Stage IV (Stage 4).2
Lung cancer metastasis
Cells from the original tumor often break away and travel through the blood or lymph systems, however, many of these die or are attacked by the body’s natural defenses. Researchers are beginning to understand that metastasis occurs when certain genetic changes occur in the cancerous cells, causing them to be more resilient and productive. These changes may make the cancerous cells more difficult to treat.1
The heart pumps blood from the rest of the body through the lungs to expel carbon dioxide and pick up oxygen. The oxygenated blood is then pumped back through the body. This process provides opportunity for lung cancers to be spread to other organs. Lung cancer can spread to any number of organs in the body, however, metastases from lung cancer are commonly found in the adrenal glands (located above the kidneys), liver, bones or brain.1
Symptoms and diagnosis
Metastatic lung cancer may cause symptoms, such as weakness, weight loss, pain (if the cancer has spread to the bones), persistent cough, or shortness of breath. Some people with metastatic lung cancer do not have symptoms.1,3
During diagnosis and staging of lung cancer, the lymph nodes in the lungs and in the chest cavity can be biopsied to determine if the cancer has spread. The biopsy may be done using a very thin needle and local anesthesia (to avoid pain at the biopsy site), or it may be done during surgery. The tissue from the biopsy is then examined under a microscope by a pathologist.2
Additional imaging that is used to determine metastases from lung cancer include:
- CT (computed tomography) scan
- PET/CT (positron emission tomography/computed tomography)
- MRI (magnetic resonance imaging) 1,2
Treatment
Treatment for the metastases is similar to the treatment of the original lung cancer and may include chemotherapy, targeted therapy, radiation therapy, and in some cases, surgery.2