Lung Cancer

Accurate Testing Guides Your Personalized Treatment Plan

Improved diagnosing methods in lung cancer have led to more personalized treatment options. By understanding the characteristics and genomics of the cancer, doctors are able to choose treatments that target specific abnormalities in some types of lung cancer. Your doctor will often use the following imaging tests, blood tests, biopsies and biomarker testing to understand your unique type of lung cancer.

Imaging Tests

Imaging tests are often used early to diagnose lung cancer. These tests make detailed pictures of areas inside the body using different forms of energy, such as X-rays, ultrasound, radio waves and radioactive substances. One or a combination of these tests may be used to diagnose disease, plan treatment or find out how well a treatment is working. Some of the commonly used imaging tests for these purposes include the following.

Computed tomography (CT) produces three-dimensional, cross-sectional X-ray images, so it can provide more precise details than a standard X-ray. CT scans provide an excellent assessment of the size of lymph nodes; however, the size doesn’t always indicate whether the nodes are involved with cancer.

Positron emission tomography (PET) images are not as finely detailed as those on a CT scan, but they can provide helpful information, especially whether the cancer has spread to other sites. PET is particularly useful if your doctor thinks cancer has spread beyond the lung but does not know where. It is also helpful in distinguishing cancerous lesions from benign (noncancerous) lesions.

Magnetic resonance imaging (MRI) may be done to look for metastasis (spread) in other parts of the body. It is most valuable for detecting it in the brain or spinal cord. A brain MRI is commonly done in the initial staging of lung cancer.

A bone scan determines whether lung cancer has metastasized (spread) to bone and is usually done only if a person has symptoms of metastasis. A bone scan may not be needed if a PET is done because that will show if cancer has spread to bone.

Using endobronchial ultrasound (EBUS), the doctor can examine areas in the space between the lungs (mediastinum), including lymph nodes.


A biopsy is a procedure to collect a sample of tissue or cells to examine under a microscope to see if cancer cells are present. Obtaining and analyzing a biopsy sample are crucial to diagnosing the type of lung cancer you may have, which will determine the type of treatment you may receive. A biopsy can be done by several methods, some of which are listed here.

A bronchoscopy allows your doctor to look inside the lungs and the large airways in the lungs (bronchi) for abnormal areas. The doctor will insert a bronchoscope (a thin tube-like instrument) through your nose or mouth into the trachea and lungs. 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.

A core needle biopsy uses a needle inserted directly into the tumor to remove cells that will help determine the type of lung cancer and for molecular testing. This biopsy provides a larger tissue sample than a fine-needle aspiration, which may be important for additional molecular and biomarker testing.

Using endobronchial ultrasound (EBUS), the doctor may choose to insert a biopsy needle through the bronchoscope to obtain a tissue sample for a pathologist to evaluate.

Fine-needle aspiration is a type of biopsy used to evaluate a possible lung tumor. In this test, cells are removed through a thin needle inserted directly into the tumor. The cells are examined under a microscope for signs of cancer. The doctor who performs this test may use ultrasound or CT to guide the placement of the needle. Ask your doctor if this biopsy will provide enough tissue for molecular testing.

Liquid biopsy for circulating tumor markers is a minimally invasive procedure that is used to test a blood sample or pieces of DNA from the tumor cells.

Mediastinoscopy is a surgical procedure to examine organs, tissues and lymph nodes between the lungs. The doctor can examine the area and remove tissue samples from lymph nodes. Mediastinotomy is a similar procedure that gives the doctor access to lymph nodes that cannot be reached by mediastinoscopy.

Thoracentesis removes fluid that has collected in the space around the lungs (pleural space). For this procedure, a needle will be inserted into the pleural space to draw out the fluid, which is then analyzed.

Thoracoscopy looks for cancer that has spread to the spaces between the lungs and the chest wall. The doctor can remove suspicious tissue for examination.

Video-assisted thoracoscopic surgery (VATS) uses a thin tube-like instrument with a ca-mera on the end to examine the lung and chest wall and remove some lung cancer tumors.

Other Tests

Your doctor may order additional diagnostic tests that look at blood, tissue and mucus.

A complete blood count (CBC) measures the number of red blood cells, white blood cells and platelets in a blood sample. Your blood counts may be abnormal – too low or too high – because of cancer, effects of treatment or another health problem.

A comprehensive metabolic panel is a blood test that measures your sugar (glucose) level, electrolyte and fluid balance, kidney function and liver function.

Immunohistochemistry uses antibodies to test for certain antigens (markers) in a tissue sample. It may be used to determine the difference between lung cancer types.

With sputum cytology, a sample of your sputum is examined under a microscope to see if cancer cells are present. Sputum is the mucus coughed up from the windpipe (trachea) and bronchi (large airways).

Tumor markers can be tested in the diagnostic process to look for molecules in the blood that are produced by cancer cells or other cells in the body in response to cancer.

Monitoring Tests

Your doctor may use one or more of the following tests to monitor how the cancer is responding to treatment.

A pulmonary function test (PFT) measures how well your lungs work by how much air they can hold and how quickly air is moved into and out of them. It also measures how much oxygen is used and how much carbon dioxide is given off during breathing.

Pulse oximetry measures the level of oxygen in your blood.

Spirometry measures how much air and how fast you can breathe. This test is given to determine if you are a candidate for lung surgery or radiation therapy.

The Role of Biomarkers in Diagnosing and Treating Lung Cancer

Cancer is caused by mutations in your genes, which are pieces of DNA. Research has found several specific genetic mutations that lead to lung cancer. Doctors can test for these mutations as part of the diagnostic process by looking for biomarkers, which are the molecules produced by the cancer cells or other cells in the body in response to cancer.

Testing for biomarkers is known as molecular testing. It may include testing for specific genes, proteins or molecules of the tumor and can be measured in the blood, plasma, urine, cerebrospinal fluid or other body fluids or tissues. Biomarkers are also known as tumor markers, molecular markers, biological markers or serum markers.

Most molecular testing for lung cancer looks for epidermal growth factor receptor (EGFR) mutations and anaplastic lymphoma kinase (ALK) fusions, for which several targeted therapies have been developed. Researchers have identified other biomarkers that are involved in some types of lung cancers. The following genes may be tested if lung cancer is suspected: ALK, BRAF, EGFR, KRAS, MET, ERBB2 (HER2), NTRK, RET and ROS1.

Next-generation sequencing (NGS) is used to test these genes. This technique is capable of processing multiple DNA sequences simultaneously with more speed and accuracy than single-gene tests. NGS can be done on both tumor tissue and blood and, at present, can detect abnormalities that may be treated with specific therapies.

To find out if you are a candidate for immunotherapy, your doctor may also look for the following factors along with molecular testing:

  • PD-L1 expression may be tested to determine if the tumor cells or immune cells in the tumor’s microenvironment contain a higher level, which may mean you could be a good candidate for immune checkpoint inhibitors. Research has shown that people with a high level of PD-L1 expression sometimes respond better to immunotherapy. In addition, the level of expression will help your doctor determine whether to give immunotherapy alone or in combination with chemotherapy.
  • Not everyone with a high PD-L1 expression should be given immunotherapy, and not all people who receive immunotherapy respond. In some cases, people with high expressions do not respond to immunotherapy. Some people with a low PD-L1 expression do respond but less often.
  • Tumor mutational burden (TMB) is an assessment of the number of genetic mutations in a tumor. It can also help doctors determine if you will respond to immunotherapy. It is believed that the higher the TMB level, the more likely you will be to respond.
  • Microsatellite instability-high (MSI-H) or deficient mismatch repair (dMMR) may be tested to determine if the cancer is caused by genes that have problems repairing themselves. MSI-H describes cancer cells that have a greater than normal number of genetic markers called microsatellites, which are short, repeated sequences of DNA. Every time a cell reproduces itself, it makes a copy of its genes and DNA. During the process, errors in duplication can be made, much like a misspelled word. The body normally corrects the error, but sometimes it isn’t caught and fixed. It then becomes a mutation that is reproduced in later versions of the cell. When cells lose the ability to correct errors, it is known as deficient mismatch repair (dMMR). Cancer cells that have large numbers of microsatellites may have defects in the ability to correct mistakes that occur when DNA is copied. Cancers with MSI-H features appear to respond better to immunotherapy, though this is rare in lung cancer.

It is important to note that not all people who receive immunotherapy respond. Researchers are not sure why this happens, and more research is needed so immunotherapy is only given to someone who may respond to it.

Key Takeaways

  • Many types of tests may be used to diagnose lung cancer.
  • Some of the same tests may be used to monitor how your lung cancer is responding to treatment.
  • Certain biomarker tests look for specific abnormalities in the tumor that will help guide treatment.
  • Ask your doctor if you will have biomarker testing.

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?
  • Will any of the procedures be painful?
  • Will my biopsy specimen be large enough for multiple biomarker tests?
  • Which tests will be run?
  • If a biomarker test is positive, how will that affect my treatment options?
  • Will I need to be sedated?
  • Has cancer spread beyond my lungs?
  • How will we know if the cancer is responding to treatment?


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