Many people with lung cancer are all too aware that lung cancer can spread. Nearly 40% of those diagnosed with lung cancer already have metastases to other parts of the body. How and where does lung cancer metastasize?
How Does Lung Cancer Spread?Lung cancers can spread when cells break off from the tumor, and travel through the bloodstream or the lymphatics (vessels in the body through which lymph and white blood cells travel) to distant regions of the body and grow. This process is called metastasis.
It is important to distinguish between primary (where a cancer starts) and secondary cancers when talking about the spread or metastasis of cancer. A primary lung cancer that spreads to bone is referred to as “lung cancer metastatic to bone,” not “bone cancer.” Similarly, a lung cancer that spreads to the brain is termed “lung cancer metastatic to the brain” rather than “brain cancer.”
Where Does Lung Cancer Spread?Lung cancer can spread to nearly any region of the body, but the most common areas are the lymph nodes, liver, bones, brain, and adrenal glands.
Spread to Lymph NodesMost lung cancers first spread to lymph nodes in the chest near the tumor. As cancer progresses, cancer cells can travel to areas in the chest further from the initial tumor, and then on to other regions of the body. Unlike metastases to other regions of the body, spread of lung cancer to the lymph nodes doesn’t mean that it is metastatic (stage 4 non-small cell or extensive stage small cell lung cancer). All stages other than stage 1 non-small cell lung cancer can include cancers that have spread to lymph nodes.
Most of the time, spread of lung cancer to the lymph nodes doesn’t cause any symptoms. When these cancers extend to lymph nodes beyond the lungs, you may notice a lump in your neck or your armpit, similar (but usually firmer) to the swollen glands you may have had in the past with a sore throat.
Spread to BoneRoughly 30 to 40% of people with advanced lung cancer have spread (metastases) to bones. The most common bones to be affected are the spine (especially the vertebrae in the chest and lower abdominal area), the pelvis, and the upper bones of the arms and legs (humerus and femur). Lung cancer is also somewhat unique in that it can spread to the hands and feet.
The most common symptom of bone metastases is pain. Often the pain begins gradually, feeling like a muscle pull or strain, and progresses to more severe pain. Due to weakening of the bone from the tumor, some people develop fractures (pathological fractures) that occur with minimal trauma or even during normal daily activities.
If lung cancer spreads to the spine, it may put pressure on the spinal cord (spinal cord compression). This may cause weakness or tingling in your legs or difficulty walking. Cancers that metastasize to bone may also breakdown bone releasing calcium into the blood (hypercalcemia) causing symptoms of confusion, muscle weakness, and loss of appetite among others.Tests to look for bone metastases may include a bone scan, PET scan, CT or MRI. The primary goal of treatment of bone metastases is to reduce pain and to repair or prevent fractures that occur. Options include pain medication, radiation therapy, medications to try to prevent the breakdown of bone, and surgery to stabilize bones.
Spread to the BrainLung cancer is the most common cancer that spreads to the brain, and at least 40% of people with advanced lung cancer will develop brain metastases sometime during their disease. Both non-small cell lung cancer and small cell lung cancer can spread to the brain. Small cell lung cancer can spread to the brain rapidly, often before a diagnosis is even made. Prophylactic cranial irradiation (PCI), a type of radiation therapy, may be used to attempt to prevent this from occurring.
Lung cancer that has spread to the brain can cause symptoms both by destroying brain tissue, and by creating inflammation and swelling that places pressure on structures in the brain. In roughly a third of people, no symptoms are present.
Common symptoms can include headaches, seizures, loss of balance and coordination, difficulty with speaking, vision changes, loss of memory and personality changes, weakness on one side of the body, and fatigue.
Lung cancer metastatic to the brain is usually diagnosed with either a CT scan or an MRI of the brain.
Treatment is primarily palliative, meaning that the goal is to control symptoms and not to try to cure the cancer. Steroids may be used to decrease swelling. Pain medications and anti-seizure medications may be used to control headaches and seizures. Radiation therapy may be very effective in reducing symptoms for some people. In rare instances, for example, if only one tumor is present, surgery may be considered to remove the tumor or reduce the size of the tumor to help with symptoms.
Next page, Lung Cancer Spread to the Liver, Adrenal Glands, and Prognosis of Metastatic Lung Cancer