Tests and Diagnosis of Lung Cancer

To look for cancerous cells and to rule out other conditions a number of test can be done if lung cancer is suspected in a person.

Updated: November 24, 2017

To look for cancerous cells and to rule out other conditions a number of test can be done if lung cancer is suspected in a person. These include:

History and Physical Examination:

The presence of symptoms or signs that are suspicious for lung cancer can be revealed by a physical examination and history of the person. Signs of breathing difficulties, airway obstruction or infections in the lungs can be detected by asking about symptoms and risk factors for cancer development such as smoking.
In chronic disease of the lung, due to insufficient oxygen in the blood there may be a bluish color of the skin and the mucous membranes. Changes in the tissue of the nail beds known as clubbing, also may indicate chronic lung disease.

Chest X-ray:

When any new symptoms of lung cancer are present, the most common first diagnostic step is chest X-ray. The back to the front of the chest as well as a from the side can be viewed by this procedure. Chest X-rays may reveal suspicious areas in the lungs but are unable to determine if these areas are cancerous.
Calcified nodules in the lungs or benign tumors called hamartomas may be identified on a chest X-ray.

CT (computerized tomography) Scan:

To examine for both metastatic and lung tumor CT scans may be performed on the chest, abdomen, and/or brain.  CT scans are X-ray procedures that combine multiple images with the help of a computer to generate cross-sectional views of the body. The test is more sensitive than standard chest X-rays in the detection of lung nodules.
CT scans of the abdomen may identify metastatic cancer in the liver or adrenal glands, and CT scans of the head can reveal the presence and extent of metastatic cancer in the brain.

Magnetic resonance imaging (MRI) scans:

When precise detail about a tumor's location is required, MRI scan is done. The MRI technique uses magnetism, radio waves, and a computer to produce images of body structures. There are no known side effects of MRI scanning and there is no exposure to radiation. The image and resolution produced by MRI is quite detailed and can detect tiny changes of 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):

This 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.
PET scans measure metabolic activity and the function of tissues. PET scans can determine whether a tumor tissue is actively growing and also determine the type of cells within a particular tumor.
PET scanning may also be integrated with CT scanning which is known as PET-CT scanning. Integrated PET-CT has been shown to improve the accuracy of staging of lung cancer over PET scanning alone.

Bone scans:

Bone scans are used to create images of bones on a computer screen or on film. This is done to determine whether a lung cancer has metastasized to the bones. In a bone scan, a small amount of radioactive material is injected into the bloodstream and collects in the bones, especially in abnormal areas. The radioactive material is detected by a scanner, and the image of the bones is recorded on a special film for permanent viewing.

Sputum cytology:

If you have a cough and are producing sputum, looking at the sputum under the microscope can reveal the presence of lung cancer cells.
A sputum cytology examination can be done if a tumor is centrally located and has invaded the airways. This is the most risk-free and inexpensive tissue diagnostic procedure. But since tumor cells will not always be present in sputum even if a cancer is present it is not useful always. The noncancerous cells may also look like cancer cells when they undergo changes in reaction to inflammation or injury.


Examination of the airways through a thin, fiberoptic probe inserted through the nose or mouth is known as bronchoscopy. The procedure may reveal areas of tumor that can be sampled (biopsied) for diagnosis by a pathologist. A tumor in the central areas of the lung or arising from the larger airways is accessible to sampling using this technique.
More serious but rare complications of this procedure 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:

Needle biopsies are particularly useful when the lung tumor is peripherally located in the lung and not accessible to sampling by bronchoscopy. A thin needle through the chest wall is inserted into the abnormal area in the lung and cells are suctioned into the syringe and are examined under the microscope for tumor cells.  A small risk of an air leak from the lungs is there in this procedure.


When lung cancers involve the lining tissue of the lungs (pleura) and lead to an accumulation of fluid in the space between the lungs and chest wall, this test is done. A sample of this fluid can be taken with the help of a thin needle which may reveal the cancer cells and establish the diagnosis.

Major surgical procedures:

If none of the above mentioned methods yields a diagnosis, surgical methods must be followed to obtain tumor tissue for diagnosis.These can include:
  • Mediastinoscopy which is examining the chest cavity between the lungs through a surgically inserted probe with biopsy of tumor masses or lymph nodes that may contain metastases.
  • Thoracotomy is a surgical opening of the chest wall for removal or biopsy of a tumor.
Both mediastinoscopy and thoracotomy carry the risks of major surgical procedures and complications such as bleeding, infection, and risks from anesthesia and medications.

Blood tests:

These test may reveal biochemical or metabolic abnormalities in the body that accompany cancer. These can be
  • Elevated levels of calcium or alkaline phosphatase may accompany cancer that is metastatic to the bones.
  • Elevated levels of aspartate aminotransferase (AST or SGOT) and alanine aminotransferase (ALT or SGPT) which are normally present within liver cells, indicates liver damage.

Molecular testing:

Molecular genetic testing is done to look for genetic mutations in the tumor for advanced NSCLCs.  Testing may be done to look for mutations which are responsible for tumor growth or abnormalities in the epithelial growth factor receptor (EGFR) and the anaplastic lymphoma kinase (ALK) genes. Other genes that may be mutated include MAPK and PIK3.

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