Cancers that can spread from their original locations are called secondary cancers. This process, called metastasizing, moves the cancers through the bloodstream, lymphatic system, or by direct extension to a new location. One or many of the cancerous cells of the primary cancer (where the disease originated) can break off and slip into the bloodstream or lymphatic system to reach other organs.
Cancerous cells in the lungs as well can appear there without having originated there; in children, cancers of the lungs usually manifest through this process. Cancer that appears in the lungs but did not originate there is called secondary lung cancer. Even though it affects the lungs, secondary lung cancer is named according to the type of cancer it originated from, the primary cancer. For example, breast cancer that spreads to the lungs and becomes secondary lung cancer would still be considered breast cancer.
While nearly every type of cancer has the ability to metastasize and spread to the lungs, some do so more commonly than others. Secondary lung cancer is usually a result of bladder, breast, prostate, or colon cancer. Sarcoma, Wilms tumor and neuroblastoma also tend to migrate to the lungs.
Secondary lung cancer, in addition to being a disease in itself, is also usually an indication that the primary cancer has reached an advanced stage, though this is not always the case. Signs of secondary lung cancer include persistent cough, breathlessness, coughing up blood, and chest pain. These symptoms, in addition to being similar to those for primary lung cancer, also mimic several less serious diseases. A diagnosis of secondary lung cancer may therefore require x-rays, CT scans, MRIs, PET scans, or biopsies.
Symptoms of secondary lung cancer can interrupt daily activities for sufferers. But there are ways to manage and treat the symptoms. Medication can help address symptoms such as breathlessness, cough and chest pain. Other symptoms must be managed by the patient through awareness. Some patients begin to fear they will choke, due to their increased difficulty with breathing, but should be aware that this is unlikely. Others may be distressed by coughing up blood, but should know that coughing up a little blood is not unusual to patients with secondary lung cancer. Only those coughing up large amounts of blood need to seek treatment for this symptom.
Secondary lung cancer can also cause a build up of fluid in the lungs, a condition termed pleural effusion. This fluid may be drained out of the lungs to relieve pain and difficulty breathing, though it may build up again over time.
Treatment for secondary lung cancer is similar to that for primary lung cancer, and includes surgery, chemotherapy, and radiation therapy. However, in secondary lung cancer in particular, chemotherapy is the preferred treatment option. This is because secondary lung cancer is an indication that the primary cancer has spread into the bloodstream. In such cases, removing visible tumors through surgery is not effective, as other cancerous cells can be present in the body without being visible. Chemotherapy can target even those cells CT scans cannot see, making it the most common treatment choice.
However, a cure is unlikely and the five-year survival rate for those diagnosed with secondary lung cancer is not promising. The cancer can sometimes be cured via surgery, but this outcome is rare.