Your Guide to Lung Cancer: Everything to Know

Medically Reviewed By Adithya Cattamanchi, M.D.
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Lung cancer, or bronchogenic carcinoma, is a form of cancer that originates in the lungs. There are different types of lung cancer, namely non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC). Lung cancer is the presence of malignant cells that begin in the lungs. Malignant lung cells grow much faster than normal lung cells. Because of this growth, lung cancer can spread throughout one or both lungs. Eventually, these cells can spread to the rest of the body.

Read on to find out more about the types of lung cancer. This guide also includes information about symptoms of lung cancer, treatments, when to contact a doctor, and more.

What are the types of lung cancer?

There is a conceptual picture of lungs.
Beatrix Boros/Stocksy United

Each year, there are around 225,000 new cases of lung cancer in the United States. NSCLC accounts for around 80–85% of lung cancer cases. SCLC is less common, accounting for around 10–15% of lung cancer cases. Other tumors may also occur in the lungs.

Subtypes of NSCLC include:

  • adenocarcinoma
  • squamous cell carcinoma
  • large cell (undifferentiated) carcinoma
  • adenosquamous carcinoma
  • sarcomatoid carcinoma

SCLC is also known as oat cell cancer and typically grows faster than NSCLC. SCLC may respond better to chemotherapy or radiation therapy.

Learn more about the differences between NSCLC and SCLC.

What are the symptoms of lung cancer?

Lung cancer may not have any symptoms in its earliest stages. It is important to contact your doctor when you first notice symptoms to increase the chance of early diagnosis.

Symptoms of lung cancer include:

What causes lung cancer?

Smoking causes around 90% of lung cancer cases. However, people who do not smoke may also develop lung cancer.

Other causes of lung cancer include:

  • exposure to secondhand smoke
  • exposure to airborne carcinogens, such as radon and asbestos
  • inherited gene mutations, which increase the risk of developing lung cancer

Metastasis of cancer from other areas in the body, such as the breastbone, can also cause cancer in the lungs.

Smoking and secondhand smoke

Cigarette smoking and exposure to secondhand smoke are responsible for most cases of lung cancer. Exposure to smoke damages the cells that line the lungs. Over time, these damaged cells multiply and form malignant tumors, crowding and destroying healthy cells.

If you currently smoke and are looking for ways to stop, view our article for tips to quit smoking.

Exposure to cancer-causing agents

Lung cancer can develop in people who do not have a history of smoking or exposure to secondhand smoke. Exposure to the following cancer-causing agents, or carcinogens, can increase your risk of lung cancer:

  • radon, a radioactive gas that can become concentrated inside poorly ventilated buildings and water from deep wells
  • hazardous chemicals, including:
    • asbestos
    • uranium
    • some petroleum products
  • elements that contribute to metal production, such as:
    • arsenic
    • cadmium
    • chromium
    • nickel
  • air pollution, including exhaust smoke and other particle pollution

Inherited gene mutations

People can inherit gene mutations that increase the risk of developing cancer. However, experts do not believe heredity plays a significant role in lung cancer.

Metastasis of another cancer

Cancer of the lung can also occur due to cancer metastasis from areas in the body.

Wherever cancer begins in the body is the primary cancer. Anywhere the cancer spreads beyond that is secondary cancer because it occurs in a secondary location. Cancer in the lung occurring after another cancer metastasizes is a secondary cancer.

What are the stages of lung cancer?

The type and stage of lung cancer help doctors determine what treatment to use. 

NSCLC stages

Lung cancer staging is very complex. A simplified view of NSCLC stages is:

  • Stage 0: Cancer in this stage is only in the top-most layer of cells lining the airways.
  • Stage 1: Cancer in this stage remains in the lung and has not spread to any lymph nodes.
  • Stage 2: Cancer in this stage may extend into the chest wall and lymph nodes near the lung. There may be two or more separate tumor masses in the same lung. This cancer has not spread to distant sites in the body.
  • Stage 3: Cancer in this stage may have spread to nearby lymph nodes or other organs in the chest. There may be two or more tumors in the same lung or partial blocking of a bronchus (airway). This cancer has not spread to distant sites in the body.
  • Stage 4: Cancer in this stage grows extensively beyond the lung. It can spread to the other lung or organs in the chest, such as the esophagus. It may have reached distant lymph nodes and body sites, such as the brain. Another term for stage 4 lung cancer is metastatic lung cancer.

Small cell lung cancer has 2 stages:
Limited stage: In this stage, the cancer is in one side of the chest.
Extensive stage: This stage is metastatic small cell lung cancer.

Find out more about the types and stages of lung cancer.

What are the treatments for lung cancer?

Lung cancer treatment can depend on the type and stage of cancer. You can find out detailed information about treatments for lung cancer here.

Examples of treatments for NSCLC include:

  • surgery
  • chemotherapy
  • radiation therapy
  • targeted drug therapy
  • immunotherapy
  • radiofrequency ablation

Learn more about treatments for NSCLC.

Examples of treatments for SCLC include:

  • chemotherapy
  • radiation therapy
  • immunotherapy
  • surgery

Learn more about specific types of treatments for cancer:

When should I contact a doctor?

Contact your doctor as soon as you notice symptoms. Lung cancer may not cause any symptoms in the early stages. However, seeking medical advice as soon as you experience symptoms will help you receive the earliest possible diagnosis.

How do doctors diagnose lung cancer?

Your doctor may take your full medical history and conduct a physical examination. If you have symptoms of lung cancer, they will arrange for tests to assist with an accurate diagnosis.

Tests your doctor may order if you have signs or symptoms of lung cancer include:

  • imaging tests such as:
  • sputum cytology, which is an analysis of mucus you may cough from your lungs
  • thoracentesis, which is an analysis of fluid from your lungs
  • bronchoscopy, or needle biopsy, to remove a small sample of tissue for analysis
  • lung function tests after diagnosis of lung cancer

For more detailed information, view our guide on how doctors test for lung cancer. You can also learn what to expect with an early lung cancer diagnosis.

What are the complications of lung cancer?

Over time, lung cancer can lead to complications, either as the condition progresses or as a side effect of treatment.

Possible complications can include:

Contact your doctor if you experience any complications or side effects. They will be able to advise on steps you can take to reduce the severity.

Learn more about the possible complications of lung cancer.

Can I prevent lung cancer?

It is not possible to prevent all types of lung cancer. However, there are steps that you can take to reduce your risk of getting lung cancer.

These include:

  • quitting smoking if you currently smoke
  • staying away from tobacco and secondhand smoke
  • avoiding exposure to radon or cancer-causing agents
  • eating a healthy, balanced diet

Contact your doctor for more advice about steps to reduce your risk of lung cancer.

Learn more about lung cancer prevention.

What is the prognosis for lung cancer?

The prognosis of lung cancer depends on various factors, such as the type and stage of lung cancer. Your medical history, available treatments, and any coexisting conditions can also affect your prognosis.

A common cancer statistic is the 5-year relative survival rate. This statistic means the percentage of people alive 5 years from diagnosis time, relative to people who do not have lung cancer.

The overall 5-year relative survival rate for lung cancer is 18.6%. However, an individual’s survival may be longer or shorter than 5 years. The 5-year survival rate for lung cancer that doctors detect before it spreads beyond the lungs is 56%.

Doctors diagnose around 16% of lung cancer cases at an early stage. Contact your doctor as soon as you experience symptoms of lung cancer.

Learn more about lung cancer survival rates and prognosis.

Other frequently asked questions

Here are some more frequently asked questions about lung cancer.

What are the early signs of lung cancer?

You may not experience any symptoms of lung cancer in the early stage of the condition. Common symptoms you may experience include coughing, weakness, and new onset of wheezing. Find out more about the early symptoms of lung cancer.

Where is lung pain felt?

You may feel pain in your chest with lung cancer. This pain may worsen when you cough, laugh, or breathe deeply.

How does lung cancer usually start?

Malignant cells begin in the lungs and grow, spreading in either one or both lungs. Smoking is the main cause of lung cancer.

How can I check myself for lung cancer?

The best way to check yourself for lung cancer is to have a routine screening. In particular, you should have a yearly lung cancer screening if all of the following apply:

  • You smoke or have smoked 20 packs of cigarettes or more per year.
  • You currently smoke or quit smoking within the past 15 years.
  • You are 50–80 years old.

Learn more

Summary

There are two main types of lung cancer: non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC). The most common type is NSCLC.

Smoking is the most common cause of lung cancer. Other causes include exposure to secondhand smoke and airborne carcinogens.

You may not experience any symptoms of lung cancer in the early stages. It is important to contact your doctor as soon as you notice symptoms or have concerns about lung cancer.

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Medical Reviewer: Adithya Cattamanchi, M.D.
Last Review Date: 2022 Aug 4
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THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.
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