Lung Cancer Biomarker Testing

Not all lung cancers are the same. When scientists look at tissue from a person’s lung cancer tumor under a microscope they can tell what type (non-small cell, small cell or carcinoid) and subtype the lung cancer is.

Now there is a way to get more detailed information about the makeup of the tumor. It involves testing tumor tissue for abnormalities in its DNA and levels of specific proteins in the tumor. These tests are sometimes called biomarker, molecular, or genomic testing.  If doctors know exactly what causes the tumor to grow, a patient may be able to go on a "targeted" therapy that can slow tumor growth or shrink the tumor. Testing can also show levels of an important protein called PD-L1 which may help predict if a patient would benefit from immunotherapy.

The best time to talk to your doctor about tumor testing is before a biopsy is done. This will help ensure that the doctor removes enough tissue during the biopsy to do biomarker testing. It is also important to talk about additional biomarker testing if your cancer continues to grow after you have been on a targeted therapy.

Tell your doctor you want to discuss comprehensive biomarker testing.

If you have non-small cell lung cancer, it is important to discuss comprehensive biomarker testing. This looks for a large number of genetic alterations and proteins in all the genes known to be associated with lung cancer. This gives doctors a full picture or "genomic profile" of your unique tumor. The results will show if you have a marker that can be treated with an FDA-approved targeted therapy or if you are likely to benefit from immunotherapy. Testing results will also provide information about markers that are possibly being studied in clinical trials. This helps doctors make better-informed treatment recommendations to customize your treatment plan.

Your tissue may be tested at the hospital or clinic where you are being treated or sent to a certified company and laboratory. Your oncologist should order these tests and work with the pathology department in your hospital or clinic to arrange for your tissue to be sent to the right place. Results from this testing usually take one to two weeks. Biomarker testing is not always covered by insurance. Your doctor, nurse navigator or financial support team may be able to help with understanding your insurance coverage. Still, it is important to ask about any out-of-pocket costs associated with biomarker testing.

If your tumor wasn't tested before you started treatment, it might not be too late. Ask your doctor about testing leftover tissue or doing a liquid biopsy (blood draw).

If the tumor tissue from your biopsy was not tested for biomarkers, you may want to ask your doctor if biomarker testing is right for you and if there is any leftover tissue that can be tested. Your doctor might consider doing another tumor biopsy or performing a blood test. The blood test is called a "liquid biopsy" (a simple blood draw). Liquid biopsies may rapidly identify several types of important biomarkers and serve a complementary role to tissue biopsy in guiding treatment decisions. Lung cancer treatment can sometimes cause the makeup of a tumor to change, so some doctors may recommend another biopsy or liquid biopsy after you have already been on treatment and your tumor has become resistant to treatment. This allows doctors to get the most accurate and timely information available about your tumor.

Sometimes treatment can cause a tumor makeup to change or the tumor to become resistant to targeted therapy. Ask your doctor about re-testing your tumor after your first treatment.

Results from biomarker testing show if there are certain abnormalities in the DNA of the tumor and levels of specific proteins present in the tumor. The abnormalities found in most tumors are not inherited; they are changes that happen to your DNA over time. This means you are unlikely to pass them down to your children. Abnormalities in lung cells can happen from exposure to environmental factors like cigarette smoke, radon, asbestos or other chemicals. Some gene changes in cancer may also be random or have no known specific cause.

The results of the test may show biomarkers that can help determine what treatment options would be best for you. Not all doctors order testing for the same set of biomarkers. The markers with current FDA-approved treatments are:

• Epidermal Growth Factor Receptor (EGFR) mutation 
• Anaplastic Lymphoma Kinase (ALK) gene rearrangement
• ROS1 rearrangement
• BRAF V600E mutation
• NTRK fusion
• MET amplification or MET exon 14 skipping
• RET rearrangements
• KRAS mutation
• HER2 mutations and overexpression
• NRG1 gene fusions
• PD-L1 level (a protein that may help determine your tumor's likelihood of responding well to certain immunotherapy drugs).

Your tumor may also be tested for other gene changes, such as STK11 mutations, that are either being studied in clinical trials, have drugs approved for treatment of other types of cancer or provide information about how you might respond to a certain treatment.

Talk to your doctor about receiving the most comprehensive biomarker testing possible. The more information you have about the makeup of your tumor, the better informed you and your doctor will be to make treatment decisions.

There are currently FDA-approved lung cancer treatments for tumors showing abnormalities in EGFR, ALK, ROS1, BRAFV600E, MET, RET, KRAS, HER2 and NTRK and NRG1 genes. Treatments for biomarkers are often called "targeted therapy" because they directly target what is causing the tumor to grow. PD-L1 levels are also used to help inform whether or not a patient may benefit from immunotherapy. 

Lung cancer research is moving at a rapid pace and there continues to be drug approvals for patients whose tumors grow after being on first-line therapy. If you do not test positive for a biomarker with an approved targeted therapy, your doctor may recommend immunotherapy with or without traditional chemotherapy. Surgery or radiation may also be recommended. It may also be appropriate to enroll in a clinical trial looking at treatments for other markers.

Currently, biomarkers with approved targeted treatments are most common in patients with a subtype of non-small cell lung cancer (NSCLC) called adenocarcinoma. While other types of lung cancer may occasionally have these biomarkers, tumor testing is generally not performed for squamous cell or small cell lung cancers unless the patient does not have a smoking history. If that is the case, then biomarker testing should be performed on these cell types. Not everyone with lung cancer will have biomarkers that can be treated with targeted therapies. While lung cancer biomarker testing is a promising field, it does not guarantee a cure. All patients should have their PD-L1 levels tested to determine if they may be candidates for immunotherapy.

If your doctor doesn't recommend biomarker testing for you, you can ask why. Biomarker testing may not be right for every person. If you have questions about whether or not your tumor should be tested, you may want to seek a second opinion. It is important to work closely with your doctor to discuss all your treatment options at every step of your journey.