Julie Marks is a freelance writer with more than 17 years of experience covering health, lifestyle, parenting, science, and medical topics.

Sanja Jelic, MD, is board-certified in sleep medicine, critical care medicine, pulmonary disease, and internal medicine.

Lung cancer is the second most common cancer among men and women in the United States. Most people who are diagnosed with lung cancer are older. The average age of diagnosis is about 70. Getting an early and accurate 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 become advanced and have 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.

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:

Some risk factors for lung cancer include:

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 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:

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.

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.

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:

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.

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%.

If you're concerned about the accuracy of your test, you can ask your healthcare provider for additional diagnostic tests to confirm the results.

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:

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.

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.

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.  

Lung cancer is typically diagnosed by using a variety of tests. The most accurate way to tell if you have lung cancer is through a biopsy.

Lung cancer usually doesn't cause any symptoms until it has spread throughout the body. However, some people experience signs early on, such as a cough that doesn't go away, coughing up blood, chest pain, unexplained weight loss, fatigue, wheezing, or hoarseness.

The USPSTF recommends yearly screening with low-dose CT for people who are at high risk for lung cancer. These include those who are between ages 50–80, have a 20-pack year history of smoking, and are currently smoking or have quit smoking in the past 15 years.

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American Cancer Society. Can lung cancer be found early?.

American Cancer Society. Signs and symptoms of lung cancer.

American Cancer Society. Lung cancer risk factors.

Centers for Disease Control and Prevention. Who should be screened for lung cancer?.

American Cancer Society. Tests for lung cancer.

American Society of Clinical Oncology. Lung cancer - non-small cell: diagnosis.

Roswell Park Cancer Center. Can a cancer biopsy result be wrong.

Huang MD, Weng HH, Hsu SL, et al. Accuracy and complications of CT-guided pulmonary core biopsy in small nodules: a single-center experience. Cancer Imaging. 2019;19(1):51. doi:10.1186/s40644-019-0240-6

Moffitt Cancer Center. 12 diseases that lung cancer is commonly misdiagnosed as.

Zhu J, Zhang Y, Gao XH, Xi EP. Coronavirus disease 2019 or lung cancer: a differential diagnostic experience and management model from wuhan. Journal of Thoracic Oncology. 2020;15(8):e141-e142. doi:10.1016/j.jtho.2020.04.030

U.S. Preventive Services Task Force. Lung cancer: screening.

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