Blood tests are valuable, but they can’t diagnose lung cancer. Instead, doctors rely on imaging tests and biopsies to make an official lung cancer diagnosis. However, blood tests do offer key insights that can help guide additional lung cancer screening and treatment decisions. Collecting blood samples is also less expensive than getting scans and less invasive than performing biopsies.

Here’s how blood tests fit into the bigger picture of detecting and managing lung cancer.

How Is Lung Cancer Diagnosed?

Imaging scans, such as X-rays, computed tomography (CT) scans, and MRI scans, provide doctors with a deeper look into the lungs. These tests help reveal any suspicious changes that could indicate cancer. While imaging tests like low-dose computed tomography (LDCT) are a good first step for finding lung cancer, follow-up tests are still needed to confirm a diagnosis and plan treatment options.

An LDCT provides a three-dimensional image of the lungs. Along with spotting lung nodules, an LDCT allows doctors to see if any lymph nodes in the chest are enlarged.

If an LDCT shows signs of a problem, the next step is usually to perform a biopsy. During the biopsy procedure, a small lung or lymph tissue sample is collected. Your doctor may also perform a thoracentesis, which involves removing fluid or air near the lungs for testing. Then, the samples are examined under a microscope to check for cancer cells or signs of a different issue.

What Blood Tests Can Find

Although blood tests can’t diagnose lung cancer, they can give health care providers other useful information. Doctors use blood tests to look for signs of cancer spreading and certain genetic biomarkers that may guide their recommendations for treatment.

Tumor Markers

One type of blood test commonly used for lung cancer is the measurement of tumor markers. Tumor markers are substances cancer cells produce or that the body produces in response to cancer.

Elevated levels of these markers aren’t specific. They can point to the presence of lung cancer, another type of cancer, or a different health issue. Certain substances are associated with non-small cell lung cancer (NSCLC). Getting these test results gives doctors more information to solve the diagnostic puzzle.

Genetic Mutations

Innovations in cancer research have led to the development of liquid biopsies. This new technology involves analyzing particles of tumor DNA in the bloodstream. Liquid biopsies can detect specific genetic mutations or other abnormalities.

These tests provide a deeper look into the genetic profile of your lung cancer, giving your health care team useful information to decide whether targeted therapy options may work well for you.

Metastasis

Blood tests can also help show whether lung cancer has metastasized (spread) to other parts of the body. Information about the spread of cancer determines whether it’s early-stage or later-stage cancer. For example, high levels of liver enzymes may mean cancer has spread to the liver.

Similarly, elevated levels of calcium and other substances may suggest lung cancer has spread to the bones. If bone metastasis is suspected, your doctor may also recommend a bone scan or test.

Other Conditions

If you experience potential lung cancer symptoms, your doctor may recommend a blood test to screen for other health problems that cause similar symptoms. For instance, infections like pneumonia may make it harder to breathe, cause chest tightness, and leave you feeling lightheaded.

Although these symptoms overlap with the symptoms of lung cancer, they don’t always point to cancer. Sometimes, these symptoms may be related to allergies, asthma, heart problems, or another lung issue.

Some members of MyLungCancerTeam have experienced chest symptoms and worried their lung cancer had come back. One member shared, “I thought my cancer was back because of chest pain, but it’s an inflammation of the lining around the lungs.”

Before jumping to conclusions and assuming it’s lung cancer, ask whether a simple blood test can rule out other conditions such as an infection. “I had lung cancer surgery two months ago,” wrote one member. “Now I have tuberculosis disease, according to a blood test last week.”

Overall Health

A complete blood count (CBC) is a standard blood test that helps paint a picture of your general health and nutritional status. It measures your red blood cells, white blood cells, and platelets. Low red blood cell counts point to anemia. When platelets are low, it may mean you’re losing blood unknowingly due to bleeding. Having a low white blood cell count means your immune system may struggle to fight off infections.

This information is especially important if you’re starting or undergoing cancer treatments. One MyLungCancerTeam member reported, “I got my blood test this morning. Ready for my immunotherapy this Friday!”

A CBC helps your oncology care team determine if you may need a dietary supplement or supportive treatments to boost your strength and energy levels. They will continue to check your CBC frequently to see how your body is withstanding cancer treatments.

Blood tests can also confirm good news at follow-ups after lung cancer treatment. “Got the results of my three-year checkup,” shared one member. “All clear. X-rays and blood tests showed no cancer.”

Should You Get a Blood Test?

Since blood tests are minimally invasive and offer useful clinical information, you shouldn’t hesitate to have any blood tests recommended by your doctor. If you’re concerned about the cost, talk to your insurance carrier before scheduling your lab work to learn what you should expect to pay.

If you have a health savings account (HSA) or another type of medical expense account, you should be able to put this money toward paying for blood tests.

For those who don’t have insurance coverage, your doctor may be able to suggest a lab with lower prices or other programs and resources that can help.

Talk With Others Who Understand

MyLungCancerTeam is the social network for people with lung cancer and their loved ones. On MyLungCancerTeam, more than 12,000 members come together to ask questions, give advice, and share their experiences with others who understand life with lung cancer.

Did you get blood tests during the process of lung cancer diagnosis? Did your doctor discuss the results with you? Share your experiences and insights in the comments below, or start a conversation by posting on your Activities page.