When cancer develops, it typically forms in one part of the body. This site is known as the primary site. Unlike other cells in the body, cancer cells can break away from the primary site and travel to other parts of the body.
Cancer cells can move in the body through the bloodstream or the lymph system (vessels that carry fluids and support the immune system). When cancer cells travel to other organs in the body, this is known as a metastasis.
Metastatic cancer to the lung is a condition that develops when cancer in another area of the body metastasizes (travels) to the lung. Cancer that develops at any primary site is capable of metastasizing to the lungs. However, the primary tumors that commonly spread to the lungs include:
- bladder cancer
- breast cancer
- colon cancer
- kidney cancer
- neuroblastoma (a tumor that develops from nerve tissue. These usually occur in infants and children)
- prostate cancer
- sarcoma (a tumor that grows from bone, muscle, or connective tissue)
- Wilms’ tumor (a kidney tumor that most often affects children)
For cancer cells to metastasize, they must go through several changes. First, the cells have to break away from the primary tumor and find a way to enter the bloodstream or lymph system. Once in the bloodstream or lymph system, the cancer cells must attach themselves to a vessel that will allow them to move to a new organ—in this case, the lung.
When the cells arrive at the lung, they will need to change again in order to grow in the new location. The cells must also be able to survive attacks from the immune system. All of these changes make metastatic cancer different from the primary tumor. This means that the patient has two different types of cancer, making treatment more difficult.
If you develop metastatic cancer to the lung, you may not have any symptoms. If symptoms develop, they can be difficult to identify. This is because the symptoms may be related to health conditions other than cancer.
Symptoms of the condition can include:
- coughing up blood (bloody sputum)
- chest pain
- shortness of breath
- weight loss
Metastatic cancer must be diagnosed by your doctor. Your doctor will perform a physical exam. If you have symptoms of the disease, he or she may order additional tests. Diagnosis of metastatic cancer to the lungs can be confirmed through the following:
- bronchoscopy (a tube is inserted through your nose or mouth and snaked down your windpipe into your lungs so your doctor can view them)
- chest computed tomography (CT) scan
- chest X-ray
- studies of the sputum or fluid around the chest cavity (pleural fluid)
- lung needle biopsy (a needle is used to retrieve a sample of lung tissue or tumor while you are awake)
- surgical lung biopsy or open lung biopsy (a surgeon makes a cut in your chest to get a sample while you are in a hospital operating room)
Metastasis of cancer of the lungs may indicate that cancer has spread to the bloodstream. This might mean you have tumors that cannot be seen by your doctor. Depending on your condition, you will be presented with different treatment options.
For patients that have had their primary tumor removed, surgical removal of lung cancer followed by chemotherapy may be effective. If cancer is indeed in your bloodstream, chemotherapy is usually the recommended treatment. If you have an advanced stage of the disease or develop other cancers, chemotherapy may be the most effective treatment.
Other treatments that may be recommended by your doctor include:
- radiation therapy
- laser therapy
- placement of stents (tiny tubes) in the airways to keep them open
Experimental treatments for metastatic cancer of the lung are also available. Heat probes can be used to destroy cancer cells in the lungs. In addition, chemotherapy can be supplied directly to the affected area of the lung.
If you are diagnosed with this condition, your long-term outlook will depend on the site of your primary tumor. It will also depend on how much the cancer has spread. Primary cancers including lymphoma and testicular cancer that metastasize to the lungs can sometimes be cured with chemotherapy. Primary tumors from the kidney, bladder, skin (melanoma), or colon that metastasize to the lungs can sometimes be cured with surgery.
In most instances, a cure for metastatic cancer to the lungs is not likely. According to the National Institutes of Health (NIH), patients that develop this type of cancer rarely live more than five years after their diagnosis (NIH, 2012).
Preventing metastatic cancer is difficult. Researchers are working on preventive treatments, but nothing is yet common practice. One step toward preventing metastasis to your lungs is prompt—and hopefully successful—treatment of your primary cancer.