Lung Cancer Diagnosis

Many tests are used to diagnose and stage lung cancer. Quite often lung cancer is found before there are any symptoms through imaging performed for another health concern. It’s also found after symptoms appear, although this tends to mean the cancer is more advanced and harder to treat.

While many diagnostic tests can suggest cancer, a biopsy is the only sure way to confirm it. 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.

In addition to a physical examination, which includes reviewing your family health history, the oncologist will need to see where the cancer is located in the chest and whether it’s gone beyond the lungs.

Imaging Used to Identify Where Lung Cancer May be Located.

Chest x-ray: An x-ray of the organs and bones inside the chest. If you had one for another reason, a second x-ray is likely to focus specifically on the lungs.
CT scan of the brain, chest, and abdomen: These are a series of detailed images of the inside of the body, taken from multiple angles. This type of image can show tumors that can’t be seen on an x-ray. The various image angles allows them to also see the size, shape and position of any tumors that are found. It can also identify any lymph nodes that may look enlarged and need to be tested.
MRI (magnetic resonance imaging): A procedure that uses a magnet, radio waves, and a computer to make a series of detailed pictures of areas inside the body, such as the brain. This procedure is also called nuclear magnetic resonance imaging (NMRI). MRI’s are used most often to detect lung cancer that has spread to other areas of the body.
PET Scan (positron emission tomography scan): This type of imaging is used to see if there are cancer cells starting to grow in other areas of the body. A tiny amount of radioactive glucose (sugar) is injected into a vein to find malignant tumor cells in the body. The PET scanner rotates around the body and makes an image of where glucose is being used in the body. Malignant tumor cells show up brighter in the image because they are more active and take up more glucose than normal cells do.

Sampling Cells from the Lung to Test for Cancer

Sputum Cytology: A microscope is used to check for cancer cells in the sputum (mucus coughed up from the lungs) that is collected from the patient first in the morning for three days.
Thoracentesis: If there is fluid buildup around the lungs there will likely be a test of that to see if it contains cancer cells. A procedure that uses a needle to remove fluid from the space between the lining of the chest and the lung. A pathologist will look at the fluid under a microscope to see if cancer is present.
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. A pathologist views the sample under a microscope to look for cancer cells. A chest x-ray is performed afterward to ensure that no air is leaking from the lung into the chest.
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. This is used to look for blockages in the airways, if suspected.

Biomarker Testing for Non-Small Cell Lung Cancer

For patients with non-small cell lung cancer (NSCLC), your oncologist may test for specific genetic changes that can be identified in the cancer cells. These are non-hereditary gene mutations that are causing the cancer to grow. The tests are usually performed on the sample tissue sample collected during the biopsy. Based on the patient’s stage of lung cancer, the biomarker test results can direct the oncologist towards specific targeted therapy drugs that will help slow the growth of the cancer cells. While there are quite a few genes that are tested, these are the most commonly found genetic changes in NSCLC patients:

About 20 -25% of NSCLCs have changes in the KRAS gene. These are often adenocarcinomas found in people with a smoking history.
EGFR is a protein that appears in high amounts on the surface of 10% to 20% of NSCLC cells and helps them grow.
About 5% of NSCLCs have a change in the ALK gene. This change is most often seen in people who don't smoke (or who smoke lightly) and have adenocarcinoma.