Methods for Evaluating
Several tests are available to help your doctors learn more about your lung cancer. These tests have two important purposes. First, they provide information that helps your doctors diagnose the specific type of lung cancer you have. Second, the results let your doctor assign a stage to your lung cancer. An accurate diagnosis and stage are essential for determining your best treatment options. Here you will learn how and why these tests are done and what you can expect.
Your doctor will use a few different methods to diagnose and stage your lung cancer. Imaging studies can provide important information, but they can’t be used alone to diagnose lung cancer. Examining your tissue samples enables your doctor to definitively diagnose lung cancer. Staging procedures show how far your cancer has spread.
Imaging studies are used primarily to help define the size, shape and location of the tumor. These studies are also useful to assess other parts of the body to see whether the cancer has metastasized (spread beyond the lung), which aids in staging the disease.
Computed tomography (CT) produces three-dimensional, cross-sectional X-ray images. CT images are more precise than standard X-rays and are more likely to show a lung tumor than a standard chest X-ray. Also, CT images show the size of lymph nodes, which is important because lymph nodes often grow when cancer spreads to them. However, a lymph node can be involved without being enlarged. Because of this, other studies may be done to evaluate the lymph nodes.
A CT scanner is a large machine with a hole in the middle. For the scan, you lie on a table that moves through the hole. As the table moves slowly through the scanner, it takes pictures of your organs. A contrast material (also called a contrast dye) may be injected into a vein in your arm before the test to make your organs easier to see. The contrast material may cause a brief sensation of warmth or flushing. Aside from discomfort associated with the injection, CT is painless.
Positron emission tomography
Positron emission tomography (PET) images are not as detailed as CT images. Still, they can provide valuable information. They are especially useful if you have early-stage lung cancer because they can show whether it has spread to other sites. Knowing this can help you and your doctor decide on your best treatment option. PET scans are particularly useful if your doctor suspects that cancer has spread beyond the lung but is not sure where it has spread. PET is also helpful to distinguish cancerous lesions from benign (noncancerous) lesions. PET is not helpful, however, for finding metastasis to the brain.
Before PET is done, a small amount of radioactive glucose (sugar) is injected into a vein in your arm. Lung cancer cells use a high amount of energy and will absorb greater amounts of the radioactive sugar than normal tissue cells will. After the sugar has been absorbed by your body, you will lie on a table that slides through the opening of a large scanning machine. As the table moves through, a special camera detects any increased amounts of radioactive sugar and provides an image of the tumor or area of metastasis. PET is painless.
To diagnose lung cancer, a PET scan is often used with a CT scan, with the two tests done in the same testing session. The combination provides a more complete picture for the radiologist, who can compare areas of higher radioactivity on the PET scan with the detailed appearance of the same area on the CT scan.
Magnetic resonance imaging
Magnetic resonance imaging (MRI) is most valuable for detecting metastasis to the brain or spinal cord. Magnetic resonance images are produced through radio waves and a powerful magnet linked to a computer. You will need to lie still on a table within the tube of the MRI machine, which makes loud, repetitive clicking noises. As with CT, contrast material may be used to enhance the images. If you are claustrophobic, be sure to tell your doctor, as he or she may be able to provide medication to help you relax. MRI is painless.
A bone scan helps determine whether cancer has spread to bone. This test is often unnecessary because PET, which is used more often for people with lung cancer than with other types of cancer, can also show bone metastasis. A bone scan is usually done only when a patient has signs and symptoms of metastasis.
For the scan, a small amount of a low-level radioactive substance is injected into a vein in your arm. This radioactive substance collects in areas of metastatic disease in bone. You will then lie on a table for about 30 minutes, and a special camera will record images of areas with an increased amount of the radioactive substance. Most of the substance will be eliminated from your body within one day and will be completely gone within two days. A bone scan is painless.
Definitive diagnostic tests
Definitive diagnostic tests are tests that can specifically show whether abnormalities in the lung are cancer. For these tests, your doctor will examine samples from your body to see if lung cancer cells are present.
Sputum is the mucus coughed up from the windpipe (trachea) and bronchi (large airways). With sputum cytology, a sample of your sputum is examined under a microscope to see if cancer cells are present.
A needle biopsy is a way to remove lung tissue so that a pathologist can examine it with a microscope. Two types of needle biopsy are fine-needle and core-needle biopsies. A core-needle biopsy typically provides more tissue and so is usually preferred. An imaging study, such as CT or endobronchial ultrasound, is often used to help the doctor guide the needle to the exact area. You will receive an injection of a local anesthetic before the biopsy needle is inserted into the suspicious area.
Thoracentesis is a process to remove fluid that has collected in the space around the lungs (pleural space). For this procedure, you will receive a local anesthetic, and then a needle will be inserted into the pleural space. The needle draws out the fluid, which is then analyzed.
A bronchoscopy allows your doctor to look inside the lungs and bronchi for abnormal areas or tumors. The doctor will insert a bronchoscope — a thin, tube-like instrument — through your nose or mouth into the trachea and lungs (see illustration below). The bronchoscope has a light and lens that let the doctor examine the inside of the trachea, bronchi and lungs. Tiny tools can be inserted into the bronchoscope to obtain samples of tissue or fluid to be analyzed. You may be lightly sedated to ensure that you are comfortable during the procedure.
Staging procedures let the doctor view the lungs and surrounding area and obtain samples from nearby lymph nodes or other tissue. These procedures can help the doctor stage your lung cancer or determine how far it has spread.
With endobronchial ultrasound, also known as EBUS, a bronchoscope is inserted into the trachea, and high-frequency sound waves are used to create images. With this technique, the doctor can examine areas in the space between the lungs (mediastinum), including lymph nodes. If an area looks like it may be cancerous, the doctor can insert a biopsy needle through the bronchoscope to obtain a tissue sample for a pathologist to evaluate. You will be given a local anesthetic and be lightly sedated during the procedure.
Endoscopic esophageal ultrasound
This exam is similar to endobronchial ultrasound, but the doctor passes an endoscope (a flexible tube with a light) down the throat and into the esophagus. The doctor can see lymph nodes and look for tumors or other abnormal tissue and can also insert a needle through the endoscope to take a tissue sample. You will be given a local anesthetic and be lightly sedated for this procedure.
Mediastinoscopy involves the use of a mediastinoscope (a thin, hollow, lighted tube) to examine lymph nodes in the mediastinum. The doctor will make a small cut in the neck. Then, he or she will insert the mediastinoscope behind the sternum (breast bone). The doctor can examine the area and remove tissue samples from lymph nodes. Mediastinotomy is a similar procedure that involves a slightly larger incision between the second and third ribs on the left. This procedure gives the doctor access to lymph nodes that cannot be reached by mediastinoscopy. You will be given a general anesthetic for this procedure.
This test is done to look for cancer that has spread to the spaces between the lungs and the chest wall. You will be given a general anesthetic before the procedure. The doctor will make a small incision (cut) in the side of the chest wall and then insert a thin tube with a light and a small video camera through the incision to examine the area. If the doctor notices a suspicious area, he or she can remove the tissue for examination.
Biomarker testing of lung cancer tissue has become a vital part of diagnosis and is recommended for all people with lung cancer, especially people with an advanced diagnosis of one of the three types of non-small cell lung cancer. This testing is important because researchers have discovered molecular changes that may affect how lung cancers grow and respond to different treatments. Biomarker testing is done on tissue samples taken during biopsy. Talk to your doctor about the type of biomarker testing that is best for your particular lung cancer.
Questions to ask your medical team
Which diagnostic and staging tests do you recommend for me?
How should I prepare for these tests?
Will I need more than one test?
Has my specimen been tested for biomarkers? Should it be?
Has my cancer spread beyond my lung?