If you have any signs and symptoms of lung cancer, your doctor will suggest some tests to learn more about these issues and find their cause. You may have already had an x-ray done and been referred to a lung specialist. Or, doctors may have found an abnormal spot or nodule in your lung because you were identified as having a high risk for lung cancer and are part of a screening program.
Your doctor will explain to you which tests you will undergo and why they are needed. It is normal to feel frustrated during the process or worried about what the tests might reveal. But it is important not to assume the worst. Your doctor is simply trying to determine the reason for your symptoms or rule out certain causes.
Some tests, especially the newer molecular tests, may not be available in your area. However, it may be possible to send your samples to another laboratory in Canada that runs the tests you need. You can also ask your doctor about getting tests done through clinical trials. Your doctor may also suggest out-of-country testing. In such cases, be sure to have your doctor fill out the paperwork that you will need to get reimbursed, if possible, for these tests.
As their name suggests, these tests take an image of the structures inside the body. Just like a photo camera uses light, these procedures use x-rays, sound waves, magnetic fields, or radioactive materials to create an image.
In addition to finding where the cancer might be, imaging tests are also used to monitor how the cancer responds to treatment and if it returns after treatment.
A chest x-ray is often the first test that is done when symptoms point towards lung cancer. It is a quick and painless procedure that takes a picture using a small amount of x-ray radiation.
If the image reveals anything abnormal, other tests will be done to follow up on the findings of the x-ray. When this happens, it is important not to jump to conclusions. Keep in mind that a spot or shadow on the x-ray film might not be cancerous. It may be benign, or an infection, or something else completely. Talk to your healthcare team if you are worried or have any questions about the follow-up tests.
Computed Tomography (CT) Scan
A CT scan also uses x-rays, but creates more detailed pictures than a traditional x-ray image. For example, CT scans can detect smaller, earlier-stage tumours, as well as whether cancer has spread to nearby lymph nodes or large blood vessels, or to the rib cage. A dye called contrast media is sometimes injected or given orally before the scan to better display certain structures inside the body.
During the scan, the camera rotates around the body and takes pictures of very thin sections of the body. A computer processes these cross-sectional images and can layer them to create a three-dimensional (3D) model. (This is often likened to arranging slices of bread to reveal the structure of the entire loaf.)
Positron Emission Tomography (PET) Scan
A PET scan is often combined with a CT scan (called a PET/CT scan). The CT scan shows a detailed view of the structures of the body and the PET scan highlights any abnormalities.
Before the PET scan, a small amount of a radioactive sugar solution is injected into a vein. Cancer cells, which grow and divide rapidly, use a lot of energy and take up more of this radioactive sugar compared to the rest of the body.
Then, like CT scans, a camera that detects radioactivity takes cross-sectional images of the body; and a computer creates 3D models from them. Areas of the body that contain cancer cells, and which have absorbed more of the radioactive sugar, show up as brighter spots.
Magnetic Resonance Imaging (MRI) Scan
MRI scans are like CT scans—they both take cross-sectional images that a computer can turn into 3D models. But, instead of x-rays, MRI uses magnetic fields and radio waves to produce an image.
MRIs are rarely used to see abnormalities in the lungs. Instead, their main purpose is to detect whether cancer has spread to the brain, spinal cord, nerves, or large blood vessels.
Ultrasound uses high-frequency sound waves. The sound waves bounce off the structures inside the body and the pattern of echoes is processed by a computer to create images. Ultrasound can be used to detect the presence of excess fluid in and around the lungs, and to find out whether cancer has spread to the liver.
Bone scans can detect whether lung cancer has spread to the bones. Your healthcare team may suggest a bone scan if you have bone pain or abnormal blood tests that indicate possible bone metastases.
First, a small amount of radioactive material, known as a tracer, is injected into a vein. Large amounts of the tracer are absorbed by areas of bone that are actively growing or being repaired—for example, as a result of damage from cancer. These active areas show up as hot spots on the bone scan image.
The results of imaging tests will help your healthcare team choose which sites in the body should undergo biopsy. Also known as tissue diagnosis or pathology diagnosis, biopsy is the process of removing small amounts of tissue or fluid for laboratory testing to confirm whether cancer cells are present. It helps doctors make a more accurate cancer diagnosis. The results of the biopsy are recorded in a pathology report.
Needle biopsies are carried out under local anesthetic and do not need surgical incisions. Imaging techniques, such as ultrasound or CT scan, are often used to help guide the needle.
During a core needle biopsy, the doctor inserts a hollow needle into the tumour and removes a long, thin piece of tissue called a core. Several cores may be taken. For fine needle aspiration, the doctor uses a very thin needle to remove a small amount of tissue or fluid.
A small amount of fluid between the double-layered pleural membrane that encloses each lung helps with normal breathing. However, the pleural space between the two layers can sometimes fill up with excess fluid in a condition called pleural effusion. The excess fluid pushes on the lungs and makes it hard to breathe.
In such cases, thoracentesis is done to remove all the excess fluid and treat this condition. After applying a local anesthetic, a needle is inserted into the pleural space through the chest wall (usually from the back and between the ribs). The fluid is removed and checked for the presence of cancer cells.
Liquid biopsy is a non-invasive way to obtain samples of your cancer cells. With this technique, the pathologist only needs a sample of your blood, pleural fluid, or urine to detect whether you have cancer, and even the mutations that your cancer cells may have. Liquid biopsies are mainly used in clinical studies, and are available at a few locations in Canada. Ask your doctor if liquid biopsy is an option for you.
Endoscopes are devices that allow doctors to see inside the body. Most endoscopes are long, thin tubes with a camera and a light at one end. There is also an open channel through which medical tools, such as forceps and brushes, can be inserted to obtain biopsy samples or perform other surgical procedures. Endoscopes are named after the part of the body they are used to look at—for example, a bronchoscope is used to look for tumours or other abnormalities in the bronchi and other large airways such as the trachea.
A bronchoscope can be inserted through the nose or the mouth. Usually a flexible bronchoscope is used, along with local anesthetic for the throat and upper airways and drugs to encourage relaxation and suppress coughing. If a rigid bronchoscope is used, general anesthetic will be administered.
For an endobronchial ultrasound (EBUS), the bronchoscope is equipped with a device that emits ultrasound waves. The resulting images help to locate abnormalities in the airways, lung tissue, and nearby lymph nodes. Then, doctors can collect tissue samples from these areas by using EBUS to guide their tools.
Bronchoscopy is also used to perform surgical procedures, known as endobronchial therapies, to clear airway blockages and alleviate symptoms. Tumours can be removed with cutting tools (bronchial debridement), lasers (laser surgery), electric currents (electrocoagulation), or light-sensitive chemicals (photodynamic therapy); or by freezing them (cryosurgery). The doctor can also place stents to keep airways open.
The mediastinum is the space between the lungs. It contains the heart, large blood vessels, trachea, esophagus, lymph nodes, and other structures and tissues. General anesthetic is used during a mediastinoscopy. Then, a mediastinoscope is inserted through a small cut at the base of the neck above the breastbone. The device is used to take a sample from the lymph nodes located in the mediastinum.
Mediastinotomy is similar to mediastinoscopy, but the endoscope is inserted through a larger incision (about 4 cm long) between the ribs. This lets the doctor reach lymph nodes that cannot be reached by mediastinoscopy.
The thorax is the medical term for the chest. Thoracoscopy is carried out to examine the chest cavity—the spaces between the lungs and the chest wall, the tissue lining the cavity and lungs, the ribcage, and the diaphragm. Also known as pleuroscopy, this procedure is usually done under local anesthetic.
In a similar procedure, known as video-assisted thoracic surgery (VATS), the thoracoscope is equipped with a video camera. This device is inserted through a small cut in the side of the chest wall between the ribs; sometimes more than one cut is made to insert other tools. With this device, the surgeon can take samples of lymph nodes and lung tissue, and even remove tumours located near the surface and outer edges of the lungs.
A thoracotomy is an incision of the chest wall that is larger than those made during a thoracoscopy or VATS. The larger incision lets the doctor reach areas within the chest cavity that cannot be reached by a thoracoscope.
A sputum cytology test is used to detect the presence of cancer cells in the large airways. Lung cancer cells that are shed into the airways can mix with the mucus (sputum) located there. Sputum samples are collected during bronchoscopy by suction or washing the airways with sterile saline solution, or by coughing up sputum (sometimes after breathing in a saline mist).
Evaluation of Tissue Samples
Tissue samples obtained during biopsy and endoscopic procedures are sent to a laboratory where a pathologist will examine them. If they find cancer cells in the sample, they will further examine the cells to determine the type of cancer and how aggressive the cancer is. The information provided by the pathologist is very important for diagnosing the cancer and eventually creating the right treatment plan.
If the tissue sample is too small or was taken from an area that does not represent the entire tumour well, the pathologist may not be able to do all the necessary tests. In these situations, another biopsy may be done.
All cancer cells have mutations (abnormal genetic changes) that allow them to grow and divide uncontrollably and spread to other parts of the body. Researchers have discovered certain genetic changes that contribute to faster growth and spread of cancer, and have developed a handful of treatments to specifically target some of them.
It is quite commonplace these days for tissue samples to undergo molecular testing to find out whether someone’s cancer has one of the genetic changes for which treatments exist. Depending on other features of the lung cancer, tissue samples may be tested for genetic changes such as EGFR mutations, KRAS mutations, and ALK fusions.
Another common test looks for the presence of a molecule called PD-L1 on the surface of cancer cells. PD-L1 plays an important role in the immune system fighting cancer. Chapter 6 discusses the treatments that target PD-L1 and genetic mutations in further detail.
If your doctor has not already discussed molecular testing with you, be sure to ask them if your biopsy sample should be tested once lung cancer has been confirmed.
Complete Blood Count (CBC)
This test measures the number and quality of cells in the blood (for example, red blood cells, white blood cells, and platelets), as well as other things like hemoglobin levels. A CBC provides information about a person’s general health and any underlying medical conditions (for example, anemia, clotting problems, or infections) before they start treatment for cancer.
Regular CBC tests may be necessary once treatment starts if the treatment is known to affect the formation of blood cells in the bone marrow.
Blood Chemistry Tests
These tests measure the levels of chemicals in the blood that originate from the bones, liver, kidneys, and other organs. Abnormal levels can indicate problems with the organs, or whether cancer has spread to the bones or liver. Blood chemistry tests help your doctor choose the most appropriate treatment and tailor it for you.
Pulmonary Function Tests (PFTs)
PFTs are used to determine how well the lungs work—how much air they can hold and how well you can let air out of the lungs. PFTs will inform decisions about whether surgery is a good treatment option. If the lungs are functioning well, the doctor may consider removing a part of them to take out a tumour. The results of the PFTs will also determine how much of the lung can be safely removed.
Arterial Blood Gas
This test is used to measure the amount of oxygen and carbon dioxide in the blood. It indicates how well the lungs are working to put oxygen into and remove carbon dioxide from the blood.
Usually, blood tests involve taking blood from a vein—blood vessels in which blood flows slowly and does not contain much oxygen. But, for this test, blood from an artery is taken. This arterial blood has just passed through the lungs and brings fresh oxygen to the organs and tissues.