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Lung Cancer

Last Updated: Mar 1, 2019


lungs highlighted

Lung cancer develops when cells in the lung multiply abnormally, forming a mass (tumor) that grows destructively and invades normal tissues. Cancer can start in various parts of the lung such as the large air passages (bronchi), smaller airway branches (bronchioles), or tiny air sacs (alveoli). Lung cancer is especially lethal when it spreads (metastasizes) to distant locations in the body, such as the brain, bone, and liver. Lung cancer is the most common cause of cancer death for men and women.

Common Types of Lung Cancer:

Causes and Risk Factors

Cigarette smoke contains cancer-causing agents that directly damage lung cells. Smoking is the primary cause of lung cancer; however, people who have never smoked can also develop the disease.

Risk factors for lung cancer include:


lungs made translucent to show the bronchi within

Patients with early lung cancer are usually asymptomatic. Symptoms of lung cancer typically start when the disease is already advanced. Symptoms include:

Sometimes lung cancers produce hormones that cause dysfunction in other organs in the body. These problems are called paraneoplastic syndromes.


Lung Cancer Screening

Asymptomatic, high-risk patients can be screened with a low-dose computed tomography scan (LDCT), an imaging test used to detect lung cancer at an early stage and reduce the chance of dying from the disease.

Diagnostic Testing

Most patients with lung cancer develop symptoms late in the course of the disease. When symptoms arise, several tests are performed to confirm the diagnosis.

Lung Cancer Staging

When lung cancer is diagnosed, the next step is to determine the extent (stage) of the disease. Staging is based on the location of the tumor, number of lesions, involvement of lymph nodes, and presence of metastases. The lung cancer stage is determined by imaging studies, including a computed tomography (CT) of the chest and abdomen; bone scan (to detect spread to the bones); and magnetic resonance imaging (MRI) or CT of the brain.

The stage is important because it determines the type of treatment required and prognosis. Small, early-stage tumors are more effectively treated than advanced cancers, which have spread to the lymph nodes or metastasized.



Smoking is, by far, the main cause of lung cancer. Therefore, not smoking and avoidance of secondhand smoke will markedly reduce the risk of lung cancer.

Radon is another common cause of lung cancer. High indoor radon levels are commonly found in basements of homes and workplaces. Radon mitigation systems are available to reduce radon to a safe level.

A diet high in vegetables and fruit is strongly recommended to help prevent lung cancer, but high-dose vitamin supplements are not recommended. In fact, research shows that smokers who take high doses of beta-carotene supplements actually increase their risk of lung cancer.


Additional Resources

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Tina Shahian, PhD

Tina is a writer for Innerbody Research, where she has written a large body of informative guides about health conditions.


A communication specialist in life science and biotech subjects, Tina’s successful career is rooted in her ability to convey complex scientific topics to diverse audiences. Tina earned her PhD in Biochemistry from the University of California, San Francisco and her BS degree in Cell Biology from U.C. Davis. Tina Shahian’s Linkedin profile.


In her spare time, Tina enjoys drawing science-related cartoons.