Lung cancers can be difficult to diagnose due to a lack of regular screening. Most lung cancer cases are diagnosed after symptoms become noticeable, which often occurs in advanced stages. If you believe you're experiencing lung cancer symptoms, speak with your doctor.

Lung cancer is the second most common cancer overall in the U.S., after breast cancer in women and prostate cancer in men, according to the American Cancer Society. Most people diagnosed with lung cancer are 65 or older, and few people are diagnosed before age 45. The two main types of lung cancer are non-small cell lung cancer (NSCLC) and small cell lung cancer.

The diagnostic process begins with a visit to your doctor. They’ll start by taking a medical history and doing a physical exam to identify possible risk factors for and symptoms of lung cancer. If they find anything that suggests lung cancer, more tests will be done.

Imaging Tests

Imaging tests allow doctors to view the lungs to see if cancer is present and has spread. These tests can be used to:

• Look at suspected areas of cancer
• Determine if a treatment is effective
• Check for metastasis (cancer spread)
• Monitor for signs of recurrence (cancer growing back after treatment)

Chest X-Ray

A chest X-ray is usually the first imaging test your doctor will perform to look for abnormal areas or masses in the lung. X-rays capture images from the front and side of the chest. Chest X-rays have also been studied as a way to screen for lung cancer, but they’re not as informative as other methods. If your doctor finds an abnormality on a chest X-ray, they’ll often order a computed tomography (CT) scan to confirm the findings.

Computed Tomography Scan

A CT scan provides more detailed images than an X-ray by combining many X-ray images from different angles. It’s more likely to detect lung tumors and can also show the size, shape, and position of the tumor, as well as any spread to lymph nodes or other organs like the liver, brain, or adrenal glands​​.

Magnetic Resonance Imaging

Magnetic resonance imaging (MRI) uses strong magnets and radio waves to generate detailed images. It’s particularly useful for detecting cancer that has spread to the brain or spinal cord​.

Positron Emission Tomography Scan

For a positron emission tomography (PET) scan, a slightly radioactive form of sugar is injected into a vein and collects in cancer cells. A PET/CT scan, which combines both techniques, can be used for diagnosing lung cancer. It isn’t recommended for follow-up scans after treatment. This scan can also detect cancer that has spread to the bones, liver, adrenal glands, and other organs, but it’s not useful for looking at the spinal cord or brain.

Bone Scan

Bone scans can spot cancer that may have spread from the lungs to the bones. A slightly radioactive material is injected into the blood and collects in the bones over a few hours. Scans are then done to look for areas of higher radioactivity, which may indicate cancer.

Lung-Specific Tests

Although symptoms and imaging tests can suggest cancer, the only way to definitively diagnose it is by looking at lung cells under a microscope. The cells can be collected from mucus, fluid around the lung, or a tissue biopsy. Depending on the situation, different tests may be necessary to come to a conclusive diagnosis.

Sputum Cytology

Sputum cytology involves examining sputum (mucus) from the lungs for cancer cells. This test is particularly useful for cancers in the central airways, such as squamous cell lung cancer. However, a negative result doesn’t always rule out cancer, so additional testing may be necessary​​.

Thoracentesis

If fluid collects around the lungs (known as a pleural effusion), your doctor may perform thoracentesis. Fluid buildup can be caused by cancer spread from the lungs to the pleura, which is a protective layer around the lungs, or by an infection or heart failure.

During the procedure, the skin is numbed and a hollow needle is inserted between the ribs, draining the fluid. The fluid is then sent to a lab to check for cancer cells. Thoracentesis can also relieve pressure from fluid buildup around the lungs, making breathing easier.

Bronchoscopy

Doctors use a bronchoscope — a thin, flexible tube with a light and camera — to examine the lungs and airways for tumors or blockages. During this procedure, called a bronchoscopy, doctors can also collect tissue samples.

Needle Biopsy

When doctors want to sample tissue to look for cancer, they use a needle biopsy. The area where cancer is suspected is numbed, and then a hollow needle is inserted to remove tissue. The biopsy is then analyzed for cancer cells.

One advantage of needle biopsies is that they’re not surgical procedures, and they can be performed relatively quickly. The drawback is that the biopsy removes only a very small tissue sample, which sometimes may not have enough cancerous tissue to tell the doctor everything they need to know.

Fine Needle Aspiration Biopsy

Fine needle aspiration (FNA) biopsies use a very thin, hollow needle to extract cells and small pieces of tissue. A transtracheal or transbronchial FNA can be performed by inserting the needle through the wall of the trachea (windpipe) or bronchi (airways) during an endobronchial ultrasound or bronchoscopy. An FNA biopsy can be used to look for cancer in the lymph nodes between the lungs.

Core Biopsy

A core biopsy requires a larger hollow needle to remove tissue. Core biopsy samples are larger than FNA biopsies and can be better for diagnosing lung cancer. A core biopsy may require local anesthesia.

Transthoracic Needle Biopsy

A transthoracic needle biopsy is performed if a suspected tumor is in the outer part of the lungs. The area is numbed, and the biopsy needle is inserted through the skin on the chest wall. A CT scan or other imaging method helps guide the needle.

Tests for Lung Cancer Spread in the Chest

Several tests can be used to determine if lung cancer has spread beyond the lungs.

Mediastinoscopy and Mediastinotomy

A mediastinoscopy can examine the area behind the breastbone and in between the lungs, known as the mediastinum. The procedure involves a mediastinoscope — a flexible tube with a light, camera, and small cutting tool on the end. The scope is inserted through a small incision just above the breastbone and moved into the mediastinum.

During a mediastinoscopy, lymph nodes along the windpipe and in the major bronchial tube areas can be biopsied (removed for examination). Mediastinoscopy can also help stage lung cancer.

If some lymph nodes can’t be reached by mediastinoscopy, a surgeon may perform a mediastinotomy to remove biopsy samples. They’ll make a slightly larger incision (around 2 inches long) between the left second and third ribs next to the breastbone. Then they’ll place a tube in the incision so that they can take tissue samples.

Endobronchial Ultrasound

An endobronchial ultrasound (EBUS) bronchoscopy is used to diagnose lung cancer, inflammation, or infections. A pulmonologist (lung specialist) uses a bronchoscope to look at the trachea and lungs. EBUS can also examine lymph nodes and other structures between the lungs, allowing the doctor to take biopsies.

Endoscopic Esophageal Ultrasound

An endoscopic ultrasound (EUS) uses high-frequency sound waves to generate detailed images of the chest and lymph nodes. It can be used to follow up on CT scans or MRI findings that show possible cancer. EUS can also provide precise information on how deep a tumor is and if the cancer has spread to lymph nodes or other organs.

Thoracoscopy

Thoracoscopy allows doctors to inspect the space between the lungs and the chest wall. This procedure can also be used to take tissue samples from the outer parts of the lungs, the lymph nodes, and fluids. A thoracoscopy can be combined with video-assisted thoracic surgery (VATS) to remove tissue in early-stage lung cancer.

Genetic Testing

Genetic testing can reveal mutations (changes) in genes linked with lung cancer, most commonly non-small cell lung cancer. Identifying these mutations can help guide treatment, especially for targeted therapies​​. Commonly mutated genes include:

• EGFR — Around 10 percent to 20 percent of people with NSCLC have mutated EGFR proteins. This is more common in women, Asians, and people who don’t smoke, according to the American Cancer Society.
• ALK — About 5 percent of people with NSCLC have a mutation in the ALK gene. This is commonly seen in people with the adenocarcinoma subtype who smoke lightly or not at all.
• BRAF — About 5 percent of people with NSCLC have mutations in the BRAF gene.
• ROS1 — Between 1 percent and 2 percent of people with NSCLC have mutations in the ROS1 gene.
• RET or MET — A small percentage of people with NSCLC have mutations in either the RET or MET gene.

Blood Tests

Although blood tests don’t diagnose lung cancer directly, they can help doctors better understand your general health. The results may determine if you’re healthy enough for surgery or other kinds of cancer treatments.

Blood chemistry tests help find abnormalities in organs, like the kidneys or liver. For example, lung cancer that has metastasized to the bones may raise blood levels of calcium and alkaline phosphatase (an enzyme that breaks down proteins).

A complete blood count (CBC) panel looks at the number of different blood cells in your body. A CBC can alert your doctors to any abnormalities, such as whether you’re susceptible to infections due to a low number of white blood cells. Cancer treatments can affect blood-forming cells in the bone marrow, so CBC panels may be taken repeatedly during treatment to monitor your blood cell counts.

Talk With Others Who Understand

On MyLungCancerTeam, the social network for people with lung cancer and their loved ones, more than 13,000 members come together to ask questions, give advice, and share their stories with others who understand life with lung cancer.

Have you or a loved one been diagnosed with lung cancer? What tests led to the diagnosis? Share your experience in the comments below, or start a conversation by posting on your Activities page.