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Know the facts about lung cancer1

Lung cancer is a type of cancer that starts in the lungs. Cancer starts when cells in the body begin to grow out of control.

The Lungs

Your lungs are 2 sponge-like organs in your chest. Your right lung has 3 sections, called lobes. Your left lung has 2 lobes. The left lung is smaller because the heart takes up more room on that side of the body.

When you breathe in, air enters through your mouth or nose and goes into your lungs through the trachea (windpipe). The trachea divides into tubes called bronchi, which enter the lungs and divide into smaller bronchi. These divide to form smaller branches called bronchioles. At the end of the bronchioles are tiny air sacs known as alveoli. The alveoli absorb oxygen into your blood from the inhaled air and remove carbon dioxide from the blood when you exhale.

Taking in oxygen and getting rid of carbon dioxide are your lungs’ main functions. Lung cancers typically start in the cells lining the bronchi and parts of the lung such as the bronchioles or alveoli.

Signs and Symptoms of lung cancer2

The most common symptoms of lung cancer are:2

  • A cough that does not go away or gets worse

  • Coughing up blood or rust-colored sputum (spit or phlegm)

  • Chest pain that is often worse with deep breathing or coughing or laughing

  • Hoarseness

  • Loss of appetite

  • Unexplained weight loss

  • Shortness of breath

  • Feeling tired or weak

  • Infections (bronchitis / pneumonia) that don’t go away or keep coming back

  • New onset of wheezing

If lung cancer spreads to other parts of the body, it may cause:2

  • Bone pain (like pain in the back or hips)

  • Nervous system changes (such as headache, weakness or numbness of an arm or leg, dizziness,
    balance problems, or seizures), from cancer spreading to the brain

  • Yellowing of the skin and eyes (jaundice), from cancer spread to the liver

  • Swelling of lymph nodes (collection of immune system cells) such as those in the neck or above the collarbone

Types of lung cancer4

Non-small cell lung cancer (NSCLC)1

The main subtypes of NSCLC are adenocarcinoma, squamous cell carcinoma and large cell carcinoma. These subtypes, which start from different types of lung cells, are grouped together as NSCLC because their treatment and prognoses are often similar.


Adenocarcinomas start in the cells that would normally secrete substances such as mucus. This type of lung cancer occurs mainly in people who smoke or used to smoke, but it is also the most common type of lung cancer seen in people who don’t smoke. It is more common in women than in men, and it is more likely to occur in younger people than other types of lung cancer. Adenocarcinoma is usually found in the outer parts of the lung and is more likely to be found before it has spread. People with a type of adenocarcinoma called adenocarcinoma in situ (previously called bronchioloalveolar carcinoma) tend to have a better outlook than those with other types of lung cancer.

Squamous cell carcinoma

Squamous cell carcinomas start in squamous cells, which are flat cells that line the inside of the airways in the lungs. They are often linked to a history of smoking and tend to be found in the central part of the lungs, near a main airway (bronchus).


Large cell carcinoma

Large cell carcinoma can appear in any part of the lung. It tends to grow and spread quickly, which can make it harder to treat. A subtype of large cell carcinoma, known as large cellneuroendocrine carcinoma (LCNEC), is a fast-growing cancer that is very similar to small cell lung cancer.

A few other subtypes of NSCLC, such as adenosquamous carcinoma and sarcomatoid carcinoma, are much less common.

Small cell lung cancer (SCLC)1, 2

About 10% to 15% of all lung cancers are SCLC. It is sometimes called oat cell cancer. This type of lung cancer tends to grow and spread faster than NSCLC. In most people with SCLC, the cancer has already spread beyond the lungs at the time it is diagnosed.1 After someone is diagnosed with small cell lung cancer (SCLC), doctors will try to figure out if it has spread, and if so, how far. This process is called staging. The stage of a cancer describes how much cancer is in the body. It helps determine how serious the cancer is and how best to treat it.2

Limited stage2

This means that the cancer is only on one side of the chest and can be treated with a single radiation field. This generally includes cancers that are only in one lung, and that might also have reached the lymph nodes on the same side of the chest. Cancer in lymph nodes above the collarbone might still be considered limited stage.

Extensive stage2

This describes cancers that have spread widely throughout the lung, to the other lung, to lymph nodes on the other side of the chest, or to other parts of the body, including the bone marrow.

Other types of lung tumors

Along with the main types of lung cancer, other tumors can occur in the lungs.1

Lung carcinoid tumors

Carcinoid tumors of the lung account for fewer than 5% of lung tumors. Most of these grow slowly.1

Other lung tumors

Other types of lung cancer such as adenoid cystic carcinomas, lymphomas, and sarcomas, as well as benign lung tumors such as hamartomas are rare.1

Cancers that spread to the lungs

Cancers that start in other organs (such as the breast, pancreas, kidney, or skin) can sometimes spread (metastasize) to the lungs, but these are not lung cancers.1

Prevention of lung cancer1



Prevention offers the greatest opportunity to fight lung cancer. Smoking is still responsible for most lung cancer deaths.


Environmental causes

Researchers continue to look into the other causes of lung cancer, such as exposure to radon and diesel exhaust. Finding new ways to limit these exposures could possibly save many more lives.


Diet, nutrition and medicines

Some studies have suggested that a diet high in fruits and vegetables may offer some protection. While any protective effect of fruits and vegetables on lung cancer risk is likely to be much smaller than the increased risk from smoking, following dietary recommendations such as staying at a healthy weight and eating a diet high in fruits, vegetables, and whole grains may still be helpful.

Early detection of lung cancer1

Screening with spiral CT scans in people at high risk of lung cancer (due to smoking history) lowers the risk of death from lung cancer, when compared to chest x-rays. In recent years, a test known as a low-dose CT (LDCT) scan has been studied in people at higher risk of getting lung cancer. LDCT scans can help find abnormal areas in the lungs that may be cancer.2

A lung nodule is a small abnormal area that is sometimes found during a CT scan of the chest. These scans are done for many reasons, such as part of lung cancer screening, or to check the lungs if you have symptoms. Most lung nodules seen on CT scans are not cancer. They are more often the result of old infections, scar tissue, etc. Tests are often needed to be sure a nodule is not cancer.2

Diagnosis of lung cancer1

Fluorescence bronchoscopy

Also known as autofluorescence bronchoscopy, this might help find some lung cancers earlier, when they are likely to be easier to treat. The doctor inserts a bronchoscope through the mouth or nose and into the lungs. The end of the bronchoscope has a special fluorescent light on it, instead of a normal (white) light. The fluorescent light causes abnormal areas in the airways to show up in a different color than healthy parts of the airway.

Electromagnetic navigation bronchoscopy

Lung tumors near the center of the chest can be biopsied during bronchoscopy, but bronchoscopes have trouble reaching the outer parts of the lungs, so tumors in these areas often need to be biopsied by passing a needle through the skin. This newer approach can help a doctor use a bronchoscope to biopsy a tumor in the outer part of the lung.

Risk Factors of lung cancer you can change7

Tobacco smoke

Smoking is by far the leading risk factor for lung cancer. The risk of lung cancer for people who smoke is many times higher than for people who don’t smoke. The longer you smoke and the more packs a day you smoke, the greater your risk.

Secondhand smoke

If you don’t smoke, breathing in the smoke of others (called secondhand smoke or environmental tobacco smoke) can increase your risk of developing lung cancer.

Exposure to asbestos

People who work with asbestos (such as in mines, mills, textile plants, places where insulation is used, and shipyards) are several times more likely to die of lung cancer. Lung cancer risk is much greater in workers exposed to asbestos who also smoke. It’s not clear how much low-level or short-term exposure to asbestos might raise lung cancer risk.

Risk Factors of lung cancer you cannot change7

Previous radiation therapy to the lungs

People who have had radiation therapy to the chest for other cancers are at higher risk for lung cancer, particularly if they smoke. Women who have radiation therapy to the breast after a lumpectomy do not appear to have a higher than expected risk of lung cancer.

Air pollution

In cities, air pollution (especially near heavily trafficked roads) appears to raise the risk of lung cancer slightly.

Personal or family history of lung cancer

If you have had lung cancer, you have a higher risk of developing another lung cancer. Brothers, sisters, and children of people who have had lung cancer may have a slightly higher risk of lung cancer themselves, especially if the relative was diagnosed at a younger age. It’s not clear how much of this risk might be due to shared genes among family members and how much might be from shared household exposures.

Factors with uncertain or unproven effects on lung cancer risk

Smoking marijuana

There are reasons to think smoking marijuana might increase lung cancer risk. Marijuana smoke contains tar and many of same cancer-causing substances that are in tobacco smoke.


E-cigarettes are a type of electronic nicotine delivery system. Most e-cigarettes contain nicotine. E-cigarettes are fairly new, and more research is needed to know what the long-term effects might be, including any possible increased risk of developing lung cancer.

Treatment of lung cancer1


Doctors use video-assisted thoracic surgery (VATS) to treat small lung tumors. This procedure lets doctors remove parts of the lung through smaller incisions, which means shorter hospital stays and less pain for patients. Doctors are now studying if VATS can be used for larger lung tumors.

Targeted therapy drugs

Researchers are learning more about the inner workings of lung cancer cells that control their growth and spread. This work had led to the development of new targeted therapy drugs, many of which are already being used to treat NSCLC. Targeted drugs that are approved for use in other cancer types are now being studied in NSCLC that have a change in the RET gene.

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  1. About Lung Cancer. American Cancer Society. [Internet]. Available from: Accessed: 20/08/2023.
  2. Lung Cancer Early Detection, Diagnosis, and Staging. American Cancer Society. [Internet]. Available from: html. Accessed: 19/10/2023.
  3. Adenocarcinoma Cancers. [Internet]. Available from: Accessed: 20/08/2023.
  4. Lung cancer, small cell. [Internet]. Available from: Accessed: 20/08/2023.
  5. Small Cell Lung Cancer. [Internet]. Available from: Accessed: 20/08/2023.
  6. McWilliams A, Lam B, Sutedja T. Early proximal lung cancer diagnosis and treatment. Eur Respir J. 2009;33:656-665.
  7. Lung Cancer Causes, Risk Factors, and Prevention. American Cancer Society. [Internet]. Available from: Accessed: 20/08/2023.
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