What Is Lung Cancer?

These cells can later spread to the smaller branches of the bronchi (bronchioles) or the alveoli at the end of these branches. As the disease progresses, lung cancer can invade the surrounding body tissue, lymph nodes, and bloodstream.1

Early symptoms of lung cancer can be hard to notice. You may have difficulty breathing, a persistent cough, or coughing up blood as the disease progresses. Treatments depend on the type, what stage of cancer you are in, and the size and location of the tumor.1

Lung cancer is the third most common cancer in the United States. More than 230,000 people are diagnosed annually.2 The disease claims more than 130,000 lives every year, accounting for nearly 25% of all cancer deaths.3

Smoking is the leading risk factor for lung cancer. Healthcare providers recommend quitting smoking to lower your risk. Continuing to smoke after you develop lung cancer can quickly worsen your condition. Smoking can be a hard habit to break. Other lifestyle changes may help as you work on using less tobacco.1

Types of Lung Cancer

Healthcare providers classify lung cancer into non-small cell lung cancer (NSCLC) or small cell lung cancer (SCLC). NSCLC usually spreads slower than SCLC.4

Non-Small Cell Lung Cancer (NSCLC)

NSCLC is the most common form of lung cancer, making up about 80% to 85% of all cases.3 There are three primary types of NSCLC: adenocarcinoma, squamous cell carcinoma, and large cell carcinoma.

Adenocarcinoma is the most common type of lung cancer. Smoking causes almost 90% of all NSCLC cases. Adenocarcinoma is also the most common type of lung cancer among non-smokers.5

Small Cell Lung Cancer (SCLC)

SCLC accounts for about 15% of lung cancer diagnoses.6 Tobacco use almost always causes SCLC.

SCLC can spread to your brain, liver, and bones very quickly. There are two types of SCLC: small-cell carcinoma (oat cell cancer) and combined small-cell lung carcinoma, which is rare.6

Lung Cancer Symptoms

Lung cancer can occur without any early warning signs. A healthcare provider may detect cancer accidentally—say, if you have a chest X-ray for another reason—before you develop symptoms.

Symptoms mostly develop after lung cancer progresses into an advanced stage. Most people have chest-related symptoms, such as:7

• Chest pain
• Coughing up blood
• Hoarse voice
• Persistent infections (e.g., bronchitis and pneumonia)
• Persistent or worsening cough
• Trouble breathing
• Wheezing

Lung cancer can affect other body parts if the cancerous cells spread. Symptoms may include:8

• Bone pain
• Fatigue and weakness
• Headache
• Swollen lymph nodes
• Unexplained weight loss
• Yellowing of the skin and eyes (if the cancer spreads to the liver)