Do You Need HER2 Testing for Lung Cancer? Signs, Timing, and Next Steps

Are you or a loved one wondering whether HER2 testing is right for your non-small cell lung cancer? Testing looks for changes in the tumor that may guide treatment. This article explains who should be tested, when, and what to do next.¹

What HER2 testing looks for

HER2 testing is part of a larger process called biomarker testing or molecular profiling. It looks for changes in the cancer cells that may be targeted with specific treatments. For HER2, the test can find a gene mutation, extra copies of the gene (amplification), or extra HER2 protein. About 2 percent of people with lung cancer have a HER2 mutation.^1-4

Finding these changes matters because roughly 30 percent of lung cancers can be treated more effectively with targeted therapy than with standard chemotherapy.³

Who should get HER2 testing?

Experts advise that all people with non-small cell lung cancer have biomarker testing. Some signs make a HER2 mutation more likely, but testing is the only way to know for sure.³

Consider HER2 testing if you fall into any of the following categories:^1,4

• A history of little or no smoking – HER2 mutations are more common in people who have never smoked or smoked very little.
• Adenocarcinoma type – HER2 mutations are more often found in this type of non-small cell lung cancer.
• No other main driver found – HER2 changes usually do not appear with other main biomarkers, so testing helps complete the picture.

Even if none of these fit you, testing is still recommended. It is especially important for people who have never smoked.³

When should you be tested?

Timing matters. Testing can be done when the first biopsy is taken or at the time of surgery. For advanced cancer, current guidelines call for broad testing that checks HER2 along with other biomarkers.^3,4

Testing may also be repeated later. Any time the cancer shifts or grows, your doctor may test again because there may be new targets to treat.³

One more point on timing: It is okay not to feel rushed. A single round of chemotherapy can change your targeted treatment options and may affect trial eligibility, so many experts suggest completing testing before starting treatment when possible.³

How the test is done

There are 2 main ways to collect a sample for HER2 testing:^1,3,4

• Tissue biopsy – A small piece of the tumor is removed and studied. The best method for finding HER2 changes is comprehensive next-generation sequencing (NGS), which checks many biomarkers at once. Tissue results often take about 3 to 4 weeks.
• Liquid biopsy – When a tissue sample cannot be taken or is too small, a blood test can look for cancer changes. Blood results often come back faster, in about 2 to 3 weeks.

Some biopsy methods collect only a little tissue, which may not be enough to complete testing. Tell your doctor you want molecular profiling so they can plan the best biopsy approach. For HER2 mutations, treatment approval is tied to an FDA-approved test.^2,3

Next steps after your results

Once your results are back, ask your doctor to explain them in plain terms. Good questions include:^1,3

• What exact HER2 change do I have?
• What treatments or clinical trials fit my result?
• Was I tested for other biomarkers too?

If your results are unclear or a sample was too small, ask whether a repeat biopsy or a liquid biopsy could help. You can also ask about a second opinion at a specialized cancer center.³

Talk to your doctor

Biomarker testing is a key step in planning lung cancer care. Ask your doctor whether you have had complete testing, including HER2, and what your results mean for you. You have every right to understand your options and take part in each decision.