Lung Cancer - April 21, 2017
Should You Be Tested for Lung Cancer?
Lung cancer is the leading cause of cancer-related death in the United States, claiming more lives than colon, breast, and prostate cancer combined. According to the American Cancer Society, about 222,500 people will be diagnosed with lung cancer in 2017, and 155,870 will die from this disease. The majority (66%) of patients are diagnosed with lung cancer at age 65 or older.
Lung cancer is divided into small-cell lung cancer and non–small-cell lung cancer (NSCLC). NSCLC is the most common type, affecting approximately 80% to 85% of all patients with lung cancer. Because lung cancer usually doesn’t have symptoms at early stages (stage I and II), the majority of people are diagnosed at an advanced stage (stage III or IV), when the cancer is difficult to treat, which explains why the death rate from lung cancer is so high.
Although lung cancer can often be cured if diagnosed at an early stage, when diagnosed at late stages, in most cases that is no longer an option, which is why it’s important to know who is at risk, and who should be screened for lung cancer.
Who Is at Risk?
- Smoking is the biggest risk factor for lung cancer; about 80% of lung cancer deaths are related to smoking. But even if you don’t smoke, regularly breathing cigarette smoke of other people increases the risk
- Exposure to harmful gas or chemicals, such as radon, asbestos, or arsenic, as well as air pollution, also increases the risk for lung cancer
- If you had radiation to the chest because of other cancers, your risk for lung cancer increases, especially if you smoke
- If you had lung cancer, you are at increased risk for getting lung cancer again
- If someone in your immediate family had lung cancer, you are at increased risk for lung cancer
- People with inherited mutations (alterations in genes) are at risk for lung cancer, including abnormalities in chromosome 6 and defective DNA repair mechanisms that are susceptible to cancer-causing chemicals
- Certain genetic abnormalities, including TP53, p16, KRAS, ALK, and EGFR mutations, are not inherited, but they also increase the risk for NSCLC
Recognizing the Symptoms
Most lung cancers don’t cause symptoms until they are at a later stage, although some people have symptoms with early-stage lung cancer. Common symptoms of lung cancer include persistent cough, coughing up blood or phlegm, chest pain, hoarseness, unexplained weight loss and fatigue, shortness of breath, wheezing, ongoing bronchitis, or pneumonia.
Lung cancer that has already spread to other organs may cause bone pain; yellowing of skin and eyes; lumps near the surface of the body; and changes in the nervous system, such as headaches or dizziness, if the cancer has spread to the brain or spinal cord.
Screening for Lung Cancer
Screening (which is different from testing) for lung cancer before any symptoms appear is done to find the disease in early stages among patients at high risk. If a screening is positive, other tests will be performed to make the diagnosis.
According to the National Comprehensive Cancer Network guidelines on lung cancer screening, a low-dose CT scan is not right for everyone. People who are at high risk for lung cancer are:
- People aged 55 to 74 who have smoked at least 1 pack of cigarettes for 30 years and quit smoking less than 15 years ago
- People aged 50 or more who have smoked 1 pack of cigarettes for 20 years and have other risk factors (excluding second-hand smoke)
- People who have a family history of lung cancer should ask their doctor about screening, because of their increased risk for lung cancer
Low-dose CT scan is the only screening test that has been found to lower the risk of dying from lung cancer. This type of scan involves taking many x-rays, with a low amount of radiation, from different angles around the lungs. One low-dose CT scan is usually not enough to come to a conclusion. A series of follow-up scans are used to determine whether a nodule seen on the scan is cancerous. In general, screening should be performed annually, but some people may need to do this more frequently, if a suspicious nodule is shown on the low-dose CT scan.
A single screening test is not enough to diagnose lung cancer. If lung cancer is suspected based on a screening test or because of symptoms, other tests will need to be done to diagnose lung cancer, using a biopsy to check the tissue sample under a microscope. In some cases, it may be necessary to perform surgery to remove the whole nodule and some surrounding tissue.
Biopsy is the removal of lung cells and tissue using a needle or surgery to inspect them under a microscope
Bronchoscopy can help doctors find tumors or blockages in the larger airways of the lungs, which can often be biopsied during the procedure
Chest x-ray is often the first test your doctor will use to look for any abnormal areas in the lungs; chest x-rays can be done at imaging centers, hospitals, and in some doctors’ offices
CT scan takes many pictures to make detailed cross-sectional images of your body; it is more likely to show lung tumors than routine chest x-rays: can show the size, shape, and position of any lung tumors and can help find enlarged lymph nodes that might contain cancer that has spread from the lung
MRI is most often used after a diagnosis of lung cancer, to look for the spread of lung cancer to the brain or spinal cord
PET/CT scan combines 2 types of scans that help to pinpoint whether the cancer has spread to the lymph nodes near the lungs or to other areas, which can help determine if surgery is an appropriate option. Chest CT scan or a PET scan may also be needed after screening with a low-dose CT scan, if the screening suggests the possibility of lung cancer
Sputum cytology involves a sample of mucus from a cough (sputum) that is reviewed under a microscope to look for cancer cells
Because some lung cancers are associated with genetic mutations or abnormalities, new molecular tests have been developed to identify patients with these mutations, as well as new therapies that are designed to treat patients with these types of lung cancer. These tests are important to ensure the patient gets the best treatment for the specific type of lung cancer.
Tests for EGFR mutations. There are 3 tests that can identify patients with EGFR mutations, including the cobas EGFR Mutation Test, the cobas EGFR Mutation Test v2, and the therascreen EGFR RGQ PCR Kit
The first liquid biopsy for lung cancer is the cobas EGFR Mutation Test v2, which was approved by the FDA in 2016; unlike traditional biopsy (that uses the patient’s tissue), liquid biopsy uses the patient’s blood to identify those with EGFR mutations
Tests for ALK mutations. The 2 tests that can identify ALK mutations include the VYSIS ALK Break Apart FISH Probe Kit and the Ventana ALK (D5F3) CDx Assay
PD-1/PD-L1 tests. Testing for PD-L1 expression, which is a molecule found on cancer cells, is also important, because several immunotherapies are now available that are especially effective in patients with PD-1 or PD-L1 expression; the tests that measure PD-L1 expression include the Ventana SP263, the PD-L1 IHC 22C3 pharmDx, and the PD-L1 IHC 28-8 pharmDx.
On the Horizon
A new diagnostic test that has not yet been approved by the FDA can help reveal if lung cancer has returned in a person who had surgery for lung cancer. This new, simple test uses the patient’s own breath to recognize certain particles in the breath that signal lung cancer. Recent research results were published in 2016 and show much promise for this new test.
A new blood test for lung cancer is also in development.
NCCN guidelines on lung cancer screening
American Cancer Society