How to Correctly & Accurately Diagnose Lung Cancer

Getting an early and accurate lung cancer diagnosis is important, so you can start treatment as soon as possible and see better outcomes.

Unfortunately, most lung cancers aren’t diagnosed until they have advanced and spread throughout the body. Many symptoms of lung cancer are mistaken for other problems, which can lead to a delayed diagnosis. Additionally, healthcare providers might not consider checking for lung cancer if you’re not at high risk.

This article discusses the signs of lung cancer, tests used to diagnose it, and conditions sometimes mistaken for lung cancer.

Early Signs of Lung Cancer

Most lung cancers don’t cause symptoms until they’ve spread, but some people do experience signs when their disease is in an earlier stage.

Some possible symptoms of lung cancer to watch out for include:

• A cough that is persistent or worsens
• Coughing up blood or phlegm
• Chest, back, or shoulder pain that worsens when you cough, laugh, or breathe deeply
• Shortness of breath
• Hoarseness
• An infection, such as pneumonia or bronchitis, that worsens or keeps coming back
• Loss of appetite or unexplained weight loss
• Tiredness or weakness
• Wheezing

Lung Cancer Diagnosis

Different tests are available to help healthcare providers diagnose lung cancer. Your provider will likely choose methods based on your symptoms, medical history, and other factors.

Screening

Screening for lung cancer involves testing for the disease when you don’t yet have any symptoms or a history of lung cancer.

Healthcare providers screen by using a low-dose computed tomography (LDCT) scan to look for lung cancer in people who fall into a high-risk category. This test provides detailed images of your lungs.

At this time, the U.S. Preventive Services Task Force (USPSTF) recommends annual screening with LDCT for people who meet all of the following criteria:

• Have a 20 pack-year or more history of smoking (a pack-year is considered smoking an average of one pack of cigarettes per day for a year)
• Currently smoke or have quit smoking within the last 15 years
• Are between ages 50 and 80

Physical Exam

If you have symptoms of lung cancer, your provider might first perform a physical exam. They will look for any unusual signs, such as a cough or wheezing, that could indicate lung cancer.

Additionally, they may ask about your personal and family medical history.

Imaging

Different imaging tests are used to help healthcare providers see lung cancer in the body. A chest X-ray is usually the first test used to look for abnormal areas in the lungs.

Other imaging methods include:

• Computed tomography (CT): A CT scan uses X-rays to create detailed, cross-sectional images.
• Magnetic resonance imaging (MRI): MRI uses radio waves and magnets to create images.
• Positron-emission tomography (PET): A PET scan uses a radioactive substance, called a tracer, to look for lung cancer.

Biopsy

A biopsy involves removing a sample of tissue to test in the lab for cancer. Most of the time, using a biopsy is the only definitive way providers can tell if you have cancer in your body.

There are different techniques for performing a biopsy for lung cancer, including the following:

• Needle biopsy: A small needle is inserted through the skin to collect tissue. It’s usually performed with the assistance of a CT scan.
• Bronchoscopy: A thin tube, called a bronchoscope, is placed through your mouth or nose and into your lungs. A camera lets providers see your airways and take a sample of lung tissue under fluoroscopy guidance.
• Mediastinoscopy: Surgeons make a small incision at the top of the breastbone and take a sample of lymph nodes in the center of the chest.
• Endobronchial ultrasound: An ultrasound with a bronchoscope is used to remove tissue samples.
• Thoracentesis: A hollow needle is used to collect fluid between the lungs and chest wall.
• Thoracoscopy: Providers make an incision in the chest and insert a device with a camera to view inside and remove tissue.

Tests

Certain tests can help healthcare providers rule out other conditions and learn more about your health. 

Lab tests, including those to analyze your blood and phlegm, can reveal abnormalities that may prompt your provider to order more exams.   

A newer blood test, called a liquid biopsy, is sometimes used to diagnose specific genetic changes in people with lung cancer. This information may help providers tailor treatment approaches in the future.

Another test, called a pulmonary function test, shows how well your lungs are working.

Accuracy of Lung Cancer Diagnosis

The most accurate way to diagnose lung cancer is through a biopsy. However, it’s possible that the tissue collected can be insufficient.

Your biopsy could reveal a false positive (the test wrongly shows you have lung cancer) or a false negative (the test wrongly shows you don’t have cancer).

Experts believe an incorrect result occurs in about 1% to 2% of all surgical biopsies for cancer.

A 2019 study compared the accuracy of CT-guided core biopsies on small and large lung lesions. Researchers found the overall accuracy of biopsies was 93.9%. The accuracy for small nodules was 83.7%, and the accuracy for large nodules was 96.8%.

Lung Cancer Differential Diagnosis

A differential diagnosis is a process in which healthcare providers differentiate between the possible conditions that could be causing your symptoms.

There are many other conditions that may cause symptoms similar to those of lung cancer. Some of these include:

• Pneumonia or bronchitis
  
• Asthma or allergies
• Chronic obstructive pulmonary disease (COPD)
• Acid reflux or gastroesophageal reflux disease (GERD)
• Pulmonary embolism
• Lung effusion
• Lung abscess
• Benign (noncancerous) lung nodules
• Tuberculosis
• Lymphoma or thoracic Hodgkin’s disease
• COVID-19

The important thing to watch out for is symptoms that linger, worsen, or don’t go away at all.  Even if it isn't lung cancer, your symptoms could be a sign of a serious medical condition.

Summary

Most cases of lung cancer aren’t diagnosed until the disease has spread. However, some people experience symptoms early on, such as chronic cough, coughing up blood, tiredness, hoarseness, or chest pain.

Diagnosing lung cancer can sometimes be a lengthy process that involves different testing methods and differential diagnosis. Once you receive an accurate diagnosis, your healthcare provider can start you on treatment.

A Word From Verywell

If you experience symptoms of lung cancer, you might be worried or scared about the diagnosis you’ll receive. That shouldn’t stop you from seeing a healthcare provider. The earlier lung cancer is treated, the better your chances for a longer survival. Don’t hesitate to contact your healthcare provider if you experience unusual symptoms.