Lung Cancer Diagnosis
Doctors use many tests to detect, diagnose, and stage lung cancer. Tests are also used to see if cancer has spread (metastasized) to other parts of the body from where it started.
Lung Biopsy for Cancer Diagnosis
Before a lung cancer diagnosis, most patients go through tests including scans and blood tests that suggest the presence of cancer, but a biopsy is the test used most often to diagnose lung cancer. A biopsy is a procedure in which the doctor takes a sample of tissue for testing in a laboratory. In the case that a biopsy is not possible, the doctor may suggest other tests that will help make a diagnosis. There are a few different types of lung biopsy that can be used depending on where the cancer is located on or in the lungs.
- Fine-needle aspiration (FNA) biopsy of the lung: A CT scan, ultrasound, or other imaging procedure is used to locate the abnormal tissue or fluid in the lung. Then a small incision may be made in the skin where the biopsy needle is inserted into the abnormal tissue or fluid. A sample is removed with the needle and sent to the laboratory.
- Core Biopsy: A slightly larger sample of tissue is removed from the lung using a needle that’s bigger than the needles used in a fine-needle aspiration. This can be preferred because it gives the pathologist more tissue to evaluate when making a diagnosis.
- Transthoracic needle biopsy: If the cancer appears to be in the outer area of the lung, a biopsy can be done by placing a needle into the chest wall after numbing the area. A CT scan or a fluoroscopy is used to guide the needle to the area of the lung where the suspected cancer cells are located.
Once removed, the cells are evaluated by a pathologist. This type of doctor specializes in evaluating the cells taken from biopsies by viewing the sample under a microscope to look for cancer cells. If cancer cells are found, other characteristics of the cells may be identified such as whether it’s small cell lung cancer or non-small cell lung cancer.
Which Tests to Use for Lung Cancer Diagnosis?
Your doctor will take certain factors into consideration when choosing a diagnostic test, such as:
- Size, location, and type of cancer suspected
- Signs and symptoms
- Age and general health
- Results of earlier medical tests
In addition to a physical examination and discussion about your family health history, the following tests may be used to diagnose and stage both small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC).
Imaging Tests that Identify the Location of Lung Cancer Tumors
You may not experience all of these, but one or more may be used to see if there are multiple tumors, the size of them and whether they are in one lung, both lungs and/or in other areas of the body.
- Chest x-ray: An x-ray of the organs and bones inside the chest.
- CT Scan (CAT scan) of the brain, chest, and abdomen: These are a series of detailed images of the inside of the body, taken from multiple angles. The images are then compiled by a computer linked to an x-ray machine. A dye is either injected into a vein or swallowed to show the organs or tissues more clearly.
- PET Scan (positron emission tomography scan): A tiny amount of radioactive glucose (sugar) is injected into a vein to find cancer cells in the body, sometimes before a tumor is even detected in an area of the body. The PET scanner rotates around the body and makes an image of where glucose is being used in the body. Cancer cells show up brighter in the image because they are more active and take up more glucose than normal cells do.
- MRI (magnetic resonance imaging): A procedure in which radio waves and a powerful magnet linked to a computer are used to create detailed pictures of soft tissues areas inside the body. This is typically used if spread to the spine or brain is suspected.
- Radionuclide bone scan: This procedure is used to check if there are rapidly cancer cells growing in the bone. A very small amount of radioactive material is injected into a vein and travels through the bloodstream, where it collects in the bones and is detected by a scanner. Because PET Scans can do nearly the same thing as the bone scan, this test is used less often today than it was previously.
- Endoscopic ultrasound (EUS): A procedure in which an endoscope is inserted into the body. A probe at the end of the endoscope is used to bounce high-energy sound waves (ultrasound) off internal tissues or organs and make echoes. The echoes form a picture of body tissues called a sonogram. This procedure is also called endosonography. EUS may be used to guide fine needle aspiration (FNA) biopsy of the lung, lymph nodes, or other areas.
Other Lung Cancer Diagnosis Procedures
- Laboratory tests: Includes testing samples of tissue, blood, urine, or other substances in the body. These tests help to diagnose a disease, plan and review treatment, or monitor a disease over time.
- Sputum Cytology: A microscope is used to check for cancer cells in the sputum (mucus coughed up from the lungs).
- Bronchoscopy: A bronchoscope is a thin, tube-like instrument with a light and a lens for viewing. It is inserted through the nose or mouth into the trachea and lungs to look inside the trachea and large airways in the lung for abnormal areas. A bronchoscope may also have a tool to remove tissue samples to check under a microscope for signs of cancer.
- Thoracoscopy: Examination of the inside of the chest, using a thoracoscope. A thoracoscope is a thin, tube-like instrument with a light and a lens for viewing. Typically, an incision (cut) is made between two ribs to insert a thoracoscope into the chest for viewing or for using a tool to remove tissue or lymph node samples that are then checked under a microscope for signs of cancer. In some cases, this procedure is used to remove part of the esophagus or lung. If certain tissues, organs, or lymph nodes can’t be reached, a thoracotomy may involve a larger incision between the ribs to open the chest.
- Thoracentesis: Removal of fluid from the pleural cavity (fluid filled space that surrounds the lungs) through a needle inserted between the ribs. A pathologist will look at the fluid under a microscope to find cancer cells.
If cancer is found, additional tests may be required to finalize the cancer’s stage and grade as well as the presence of biomarkers that will dictate which type of treatment to use first.