Lung cancer occurs when cells in the lungs begin to grow out of control. Doctors usually diagnose lung cancer in older adults with a history of smoking.

Lung cancer is a leading cause of death from cancer across all genders. According to the American Cancer Society (ACS), doctors will diagnose around 237,000 new lung cancer cases in the United States in 2022. Although this illness is serious, early detection gives people the best chance of successful treatment.

Doctors use a variety of imaging and laboratory tests for lung cancer detection. These include X-rays, CT scans, PET scans, and a range of biopsies.

If people have concerns about any symptoms or their risk of developing lung cancer, they should talk with a doctor about preventive screening.

This article looks at lung cancer detection, the tests a doctor may order, and the outlook for people with this type of cancer.

A doctor looking at imaging test results to diagnose lung cancer.Share on Pinterest
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Although doctors can sometimes find lung cancer through screening tests, they often find it because the cancer is causing symptoms.

Doctors diagnose lung cancer following laboratory testing of a sample of lung cells. However, they will first take note of a person’s symptoms, ask questions about their medical history, and perform a physical exam.

The medical history helps a doctor understand someone’s lung cancer risk factors, such as smoking habits. The physical exam may reveal signs of lung cancer or any other health issues.

If a doctor believes the person may have lung cancer, they may order further tests, including imaging and lung biopsies.

Doctors use various tests to detect lung cancer, including imaging and laboratory tests.

Imaging tests create pictures of the inside of the chest and lungs. These images can help doctors understand more about areas where there might be cancer or determine if cancer has spread. They may also use imaging tests to see if treatment is working and tumors are shrinking.

Chest X-ray

A chest radiograph or X-ray uses small doses of ionizing radiation to create pictures of the lungs. These imaging studies are often the first step a doctor will use to look for suspicious areas in the lungs. If they find anything unusual, they may order further tests.

X-rays are painless and usually quick. During the X-ray procedure, a person lies down or stands between the X-ray machine and a plate that creates an image. They may need to change positions to take images from the side and front.

CT scan

A CT scan also uses X-rays. However, instead of creating one or two images, a CT scan creates detailed cross-sections of the chest. It then combines these computerized scans to display a detailed image.

Because of the extra detail, a CT scan is usually better at showing lung tumors than a chest X-ray. If a person has tumors, a CT scan can show their size, shape, and location. It can also show if cancer has spread to lymph nodes or other areas.

A person lies on a table that slides under the scanner during the procedure. The scanning machine moves over and around the chest. The radiographer may ask the person to breathe in or out or hold their breath to ensure the images are of good quality.

MRI scan

MRI scans also provide detailed images but use radio waves and powerful magnets instead of X-rays. Doctors usually use these scans to look for lung cancer that has spread to the brain or spinal cord.

Because of the strong magnetic fields, people must advise the radiologist if they have any ear implants, pacemakers, or other implanted medical devices. Additionally, people with claustrophobia may want to talk with their doctor about taking a mild sedative before the procedure.

The MRI machine is a large cylinder-shaped tunnel surrounded by a circular magnet. A person lies on the bed that slides into the tunnel, which can make some people feel claustrophobic.

PET scan

Doctors use a slightly radioactive sugar called fluorodeoxyglucose (FDG) as a tracer for the PET scan. This involves injecting FDG into the person’s blood, which collects primarily in cancer cells.

The PET scan can detect the tracer, allowing doctors to analyze the areas where it builds up.

Radiographers may combine a PET scan with a CT scan to produce even more detailed images. Doctors often use this type of PET scan in people with confirmed lung cancer.

The process for the PET scan is similar to an MRI scan. However, a healthcare professional injects the radiotracer into an arm vein before the scan. The person should avoid moving or talking as it could affect where the radiotracer travels in the body.

The scan takes around 30–60 minutes. Although it is painless, a person may feel uncomfortable remaining still.

Laboratory tests to diagnose lung cancer

Although a person’s symptoms and imaging tests may suggest lung cancer, doctors must look at lung cells in a laboratory to make a conclusive diagnosis.

They may use cells from mucus, fluid surrounding the lungs, or a biopsy of a suspicious area. The tests include the following:

  • Sputum cytology: A laboratory can look for cancer cells in a coughed-up mucus sample. Usually, the test involves samples from 3 days in a row. The test is better at finding cancers such as squamous cell lung cancers that begin in the major airways. If doctors suspect lung cancer, they may order further testing if the sputum test finds no cancer cells.
  • Thoracentesis: If a person has fluid collecting around their lungs, doctors can remove a sample with a needle to check for cancer cells.
  • Needle biopsy: If imaging reveals a suspicious area, doctors can use a hollow needle to take a small sample. Needle biopsies do not require surgery, however they may not remove enough tissue for a diagnosis or for tests on cancer cells that help doctors select appropriate anticancer medication.
  • Fine needle aspiration (FNA) biopsy: Doctors use a very thin needle to withdraw cells and small tissue samples in an FNA biopsy. They can also use this method to look for cancer cells in the lymph nodes between the lungs.
  • Core biopsy: A doctor will use a larger needle than the one required for an FNA biopsy to remove a small tube of tissue. The may prefer this method as it provides more cells to analyze.
  • Transthoracic needle biopsy: If a suspected tumor is located in the outer lungs, a doctor can insert the biopsy needle through the skin of the chest wall. They can then guide the needle to the appropriate area using fluoroscopy, which is similar to an X-ray, or a CT scan.
  • Bronchoscopy: During a bronchoscopy, doctors can look for and biopsy tumors in the large airways of the lungs.

If doctors can detect lung cancer early, there is a higher chance of successful treatment. Unfortunately, although people may experience early symptoms with some cancers, this is not always the case.

Doctors may recommend screening tests in some individuals with a high risk of developing lung cancer to help detect it even without symptoms.

In people with a high risk of lung cancer, doctors may use low dose CT scans to look for abnormal areas in the lungs. This detection program helps save lives by finding lung cancer in the early stages before a person develops symptoms.

Chest X-rays are usually the first tests doctors order to look for abnormal masses in the lungs. Then, depending on what these tests reveal, a doctor may request further testing.

In later stages of cancer, doctors may use CT scans to reveal masses in the liver, brain, or other organs that could show lung cancer has spread. They may also use MRI scans to look for signs of lung cancer that has spread to the brain or spinal cord.

If doctors do not know where cancer has spread, they may use a PET or CT scan. These scans can show cancer spread to the liver, bones, and adrenal glands but may not be as effective in looking for cancer in the brain or spinal cord.

Doctors may also use endobronchial ultrasounds to see if cancer has spread to the lymph nodes in the area between the lungs and if they need to take biopsies.

The outlook for a person with lung cancer depends on the type of cancer, its stage, and the person’s overall health.

According to the National Cancer Institute, the overall 5-year survival rate for lung cancer in the U.S. between 2011 and 2017 was 21.7%. This means around 1 in 5 people with lung cancer lived for five years or more after diagnosis.

The ACS reports that the overall 5-year survival rate for non-small cell lung cancer (NSCLC) between 2010 and 2016 was 25%. For small cell lung cancer (SCLC), the rate was 7%.

Five-year survival rates for different stages of NSCLC were:

  • 63% if the cancer had not spread outside the lung
  • 35% if the cancer had spread locally
  • 7% if the cancer had spread to distant parts of the body

Five-year survival rates for people with SCLC were:

  • 27% if the cancer had not spread outside the lung
  • 16% if the cancer had spread to nearby areas
  • 3% if the cancer had spread to distant parts of the body

Doctors can use a range of tests to see if a person has lung cancer. If individuals have an increased risk of developing lung cancer due to a smoking history or other significant factors, doctors may suggest regular screening using low dose CT scans.

If a person has symptoms of lung cancer, doctors can use imaging tests such as CT, MRI, or PET scans to look for evidence. They may then order a biopsy to take some cells from a suspicious mass, depending on what they find. They can confirm their diagnosis by looking at the cells in a laboratory.

Anyone concerned about their lung cancer risk or experiencing any symptoms should contact a doctor as soon as possible for testing. Early detection of lung cancer offers the best chance of successful treatment.