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Lung cancer screenings

Doctors use a wide range of diagnostic procedures and tests to diagnose lung cancer. These include the following:

  • The history and physical examination may reveal symptoms or signs that are suspicious for lung cancer. In addition to asking about symptoms and risk factors for cancer development, such as smoking, doctors may detect signs of breathing difficulties, airway obstruction, or infections in the lungs. Cyanosis, a bluish color of the skin and the mucous membranes due to insufficient oxygen in the blood, suggest compromised function due to the lung’s chronic disease. Likewise, changes in the tissue of the nail beds, known as clubbing, also may indicate chronic lung disease.
  • The chest X-ray is the most common first diagnostic step when any new lung cancer symptoms are present. The chest X-ray procedure often involves a view from the back to the front of the chest and a view from the side. Like any X-ray procedure, chest X-rays expose the patient briefly to a small amount of radiation. Chest X-rays may reveal suspicious areas in the lungs but cannot determine if these areas are cancerous. In particular, medical professionals may identify calcified nodules in the lungs or benign tumors called hamartomas on a chest X-ray, and these mimic lung cancer.

  • CT (computerized tomography) scans may be performed on the chest, abdomen, or brain to examine both metastatic and lung tumors. CT scans are X-ray procedures that combine multiple images with a computer’s aid to generate cross-sectional views of the body. A large donut-shaped X-ray machine takes images at different angles around the body. One advantage of CT scans is that they are more sensitive than standard chest X-rays in detecting lung nodules. That is, they will demonstrate more nodules. Sometimes medical professionals give intravenous contrast material before the scan to help delineate the organs and their positions. The most common side effect is an adverse reaction to intravenous contrast material given before the procedure. This may result in itching, a rash, or hives that generally disappear rather quickly. Severe anaphylactic reactions (life-threatening allergic reactions with breathing difficulties) to the contrast material are rare. CT scans of the abdomen may identify metastatic cancer in the liver or adrenal glands. A physician may order CT scans of the head to reveal the presence and extent of metastatic cancer in the brain.

  • The USPSTF and ACS recommend a technique called a low-dose helical CT scan (or spiral CT scan) annually in current and former smokers between ages 55 and 80 with at least a 30 pack-year history of cigarette smoking who have smoked cigarettes within the past 15 years. The lung cancer screening technique appears to increase the likelihood of detecting smaller, earlier, and curable lung cancers. Three years of low-dose CT scanning in this group reduced the risk of lung cancer death by 20%. Using models and rules for analyzing these test results decreases the need for biopsy to evaluate detected nodules when the likelihood is high the nodule is not cancerous.
  • Magnetic resonance imaging (MRI) scans may be appropriate when precise detail about a tumor’s location is required. The MRI technique uses magnetism, radio waves, and a computer to produce images of body structures. As with CT scanning, the patient is placed on a moveable bed inserted into the MRI scanner. There are no known side effects of MRI scanning, and there is no exposure to radiation. The image and resolution produced by MRI are quite detailed and can detect tiny structures within the body. People with heart pacemakers, metal implants, artificial heart valves, and other surgically implanted structures cannot be scanned with an MRI because of the risk that the magnet may move the metal parts of these structures.
  • Positron emission tomography (PET) scanning is a specialized imaging technique that uses short-lived radioactive drugs to produce three-dimensional colored images of those drugs in the tissues within the body. While CT scans and MRI scans look at anatomical structures, PET scans measure metabolic activity and tissue function. PET scans can determine whether a tumor tissue is actively growing and can help determine the type of cells within a particular tumor. In PET scanning, the patient receives a short half-lived radioactive drug, receiving approximately the amount of radiation exposure as two chest X-rays. The drug accumulates in certain tissues more than others, depending on the drug that is injected. The drug discharges particles known as positrons from whatever tissues take them up. As the positrons encounter electrons within the body, a reaction producing gamma rays occurs. A scanner records these gamma rays and maps the area where the radioactive drug has accumulated. For example, combining glucose (a common energy source in the body) with a radioactive substance will show where glucose is rapidly being used, for example, in a growing tumor. PET scanning may also be integrated with CT scanning in a technique known as PET-CT scanning. Integrated PET-CT has been shown to improve staging accuracy (see below) over PET scanning alone.

  • Bone scans are used to create images of bones on a computer screen or film. Doctors may order a bone scan to determine whether the lung cancer has metastasized to the bones. In a bone scan, a small amount of radioactive material is injected into the bloodstream. It collects in the bones, especially in abnormal areas such as those involved by metastatic tumors. A scanner detects the radioactive material, and the bones’ image is recorded on a special film for permanent viewing.

  • Sputum cytology: The diagnosis of lung cancer always requires confirmation of malignant cells by a pathologist, even when symptoms and X-ray studies are suspicious for lung cancer. The simplest method to establish the diagnosis is the examination of sputum under a microscope. Suppose a tumor is centrally located and has invaded the airways. In that case, this procedure, known as a sputum cytology examination, may allow visualization of tumor cells for diagnosis. This is the most risk-free and inexpensive tissue diagnostic procedure. Still, its value is limited since tumor cells will not always be present in sputum even if a cancer is present. Also, noncancerous cells may occasionally change the reaction to inflammation or injury that makes them look like cancer cells.

  • Bronchoscopy: Examination of the airways by bronchoscopy (visualizing the airways through a thin, fiberoptic probe inserted through the nose or mouth) may reveal tumor areas that can be sampled (biopsied) for diagnosis by a pathologist. A tumor in the lung’s central areas or arising from the larger airways is accessible to sampling using this technique. Bronchoscopy may be performed in a same-day outpatient bronchoscopy suite, an operating room, or a hospital ward. The procedure can be uncomfortable, and it requires sedation or anesthesia. While bronchoscopy is relatively safe, it must be carried out by a lung specialist (pulmonologist or surgeon) experienced in the procedure. When a tumor is visualized and adequately sampled, an accurate cancer diagnosis usually is possible. Some patients may cough up dark-brown blood for one to two days after the procedure. More severe but rare complications include a greater amount of bleeding, decreased levels of oxygen in the blood, and heart arrhythmias, as well as complications from sedative medications and anesthesia.

  • Needle biopsy: Fine-needle aspiration (FNA) through the skin, most commonly performed with radiological imaging for guidance, may help retrieve cells for diagnosis from tumor nodules in the lungs. Needle biopsies are particularly useful when the lung tumor is peripherally located in the lung and not accessible to sampling by bronchoscopy. Medical professionals administer a small amount of local anesthetic before inserting a thin needle through the chest wall into the abnormal area in the lung. Cells are suctioned into the syringe and are examined under the microscope for tumor cells. This procedure is generally accurate when the tissue from the affected area is adequately sampled. Still, in some cases, adjacent or uninvolved areas of the lung may be mistakenly sampled. A small risk (3%-5%) of an air leak from the lungs (called a pneumothorax, which can easily be treated) accompanies the procedure.

  • Thoracentesis: Sometimes lung cancers involve the lungs’ lining tissue (pleura) and lead to an accumulation of fluid in the space between the lungs and chest wall (called a pleural effusion). Aspiration of a sample of this fluid with a thin needle (thoracentesis) may reveal the cancer cells and establish the diagnosis. As with the needle biopsy, a small risk of a pneumothorax is associated with this procedure.

  • Major surgical procedures: If none of those mentioned above methods yields a diagnosis, employ surgical methods to obtain tumor tissue for diagnosis. These can include mediastinoscopy (examining the chest cavity between the lungs through a surgically inserted probe with biopsy of tumor masses or lymph nodes that may contain metastases) or thoracotomy (surgical opening of the chest wall for removal or biopsy of a tumor). With a thoracotomy, complete removal of lung cancer is rare. Both mediastinoscopy and thoracotomy carry the risks of major surgical procedures (complications such as bleeding, infection, and risks from anesthesia and medications). Physicians perform these procedures in an operating room, and the patient must be hospitalized.

  • Blood tests: While routine blood tests alone cannot diagnose lung cancer, they may reveal biochemical or metabolic abnormalities in the body that accompany cancer. For example, elevated levels of calcium or the enzyme alkaline phosphatase may accompany cancer metastatic to the bones. Likewise, high levels of certain enzymes normally present within liver cells, including aspartate aminotransferase (AST or SGOT) and alanine aminotransferase (ALT or SGPT), signal liver damage, possibly through the presence of tumor metastatic to the liver. One current focus of research in lung cancer is the development of a blood test to aid in the diagnosis of lung cancer.

  • Molecular testing: For advanced NSCLCs, health care professionals carry out molecular genetic testing to look for genetic mutations in the tumor. Mutations that are responsible for tumor growth are driver mutations. For example, testing may be done to look for mutations or abnormalities in the epithelial growth factor receptor (EGFR) and the anaplastic lymphoma kinase (ALK) genes. Other genes that may mutate include MAPK and PIK3. Specific therapies are available that may be administered to patients whose tumors have these alterations in their genes.


By reading this website, you acknowledge that you are responsible for your own health decisions. The information throughout this medical website is not intended to be taken as medical advice. The information provided is intended for general information regarding our Pulmonology services. If you are interested in finding out more, please contact our office for a personal consultation. Avoid worrisome self-diagnosis; the best pulmonology doctors will properly diagnose your problem and refer you to a specialist if necessary. No information on this site should be used to diagnose, treat, prevent, or cure any disease or condition.