Understanding lung cancer

What is lung cancer?

Lung cancer is a cancer of some of the cells in part of your lung, usually beginning in the lining of the bronchus (see “How you breathe”) or bronchioles. The medical term for a cancer that starts in the cells lining the organ is carcinoma.

Types of lung cancer

Non-small cell lung cancer (NSLC) is the most common and makes up about 80 percent of all lung cancers.

Small cell lung cancer (SCLC) makes up to about 20 percent of lung cancers.

The three main subtypes of NSCLC are adenocarcinoma, squamous cell carcinoma and large cell carcinoma. There are several other less common types of lung cancer as well. The different types of lung cancer are grouped according to the type of cell affected (see the table “Types of lung cancer”).

Mesothelioma is a rare cancer that occurs in the pleura but is not the same as lung cancer.

Many other cancers can spread to cause cancer in the lungs (for example breast, bowel and kidney), but these are secondary cancers, or lung metastases. Our lung cancer information is only about cancers beginning in the lungs (primary lung cancer).

Types of lung cancer

Non-small cell (NSCLC)

Adenocarcinoma Most common type of lung cancer with several subtypes.

Squamous cell carcinoma More often found in major airways.

Large cell carcinoma Least common type of NSCLC. Can be very large at time of diagnosis.

Small cell (SCLC) carcinoma This type grows quickly and can spread rapidly throughout the body.

Your specific type of lung cancer needs to be diagnosed to help decide on the best

What is mesothelioma?

Mesothelioma is a cancer of the mesothelium. The mesothelium lines the chest and abdomen, and covers the body organs in both the chest and abdomen. The abdomen contains the liver, stomach and bowel. In the abdomen contains the liver, stomach and bowel. In the chest, the mesothelium is called the pleura. In the abdomen it is called the peritoneum.

Sometimes mesothelioma can spread into the area around the heart (pericardium). It is the type of cancer most often linked with asbestos exposure.

For more information see the Cancer Society’s information sheet “Mesothelioma” on our website. 

You can also get a copy by phoning the Cancer Information Helpline 0800 CANCER (226 237) or from your local Cancer Society.

Causes of lung cancer

Changes or mutations to lung cells cause cancer. These changes may allow cells to grow, divide and spread around the body in an uncontrolled way.

Like many types of cancer, we don’t always know why people get lung cancer. However, there are some things that increase your risk of getting lung cancer.

Lung cancer is strongly linked to smoking (being an ‘active smoker’). However, a number of people with lung cancer have never smoked. Lung Cancer Canada states that as many as 15 percent of people with lung cancer have never smoked.

Source: http://www.ingcancercanada.ca

A non-smoker who has been exposed to smoke (a ‘passive smoker’) can have a 20 to 30 percent higher risk of developing lung cancer than non-smokers who haven’t been exposed

People exposed to asbestos may still be in some older buildings. Some people may breathe in asbestos at work or during home renovations (DIY).

Exposure to radiation and air pollution such as diesel fumes, also increases the risk of lung cancer. Contact with the processing of steel, nickel, chrome and coal gas may increase a person’s risk.

A number of people without any of the known risk factors get lung cancer.

Symptoms of lung cancer

The symptoms of lung cancer can be different from person to person. Most people have some symptoms; a few people may get some or all of the following:

  • A chest infection or cough or wheeze or worsening of an existing wheeze
  • Increased breathlessness or a shortness of breath with movement
  • Pain around the upper back, shoulders ribs or chest
  • Hoarseness or loss of voice
  • Weight loss (without dieting)
  • Low energy levels (feeling very tired for no reason)
  • You may notice you’ve begun coughing up fresh blood or the sputum (phlegm) is streaked with blood
  • A lump in the base of the neck above the collar bone
  • Neck and arm swelling and swollen veins.

You also may get symptoms such as problems swallowing, oe abdominal or joint or back pain, or increasing weakness. Having any one of these symptoms does not necessarily mean you have cancer. Some of these symptoms may be caused by other conditions. It is important to have any of these symptoms checked by your doctor.

Some people with cancer have no hints or warnings (symptoms). They learn they have lung cancer when it is seen on a chest X-ray done for some other reason. Again, talk to your doctor if you have any of these symptoms.

Key points: Understanding lung cancer

  • Lung cancers fall into two main categories: non-small cell lung cancer (NSCLC)—which includes adenocarcinoma, squamous cell carcinoma and large cell carcinoma—and small cell lung cancer (SCLC).
  • Active and passive smoking is the cause of most lung cancers.
  • Lung cancer can affect anyone. Smokers are most at risk. Lung cancer is found in people who have never smoked.
  • Other known risk factors include exposure to asbestos, radiation and air pollution; and contact with the processing of steel, nickel, chrome and coal gas.
  • Symptoms for lung cancer vary and include:
    • a cough or chest infection that doesn't go away
    • pain around the chest, upper back or shoulders
    • shortness of breath
    • wheeze
    • hoarseness
    • weight loss and/or fatigue (extreme tiredness)
    • coughing up blood.

Other people have no symptoms at all.