What is lung cancer?
Lung cancer is a growth of abnormal cells inside the lungs. Cancer cells divide and grow faster than healthy cells, forming into clusters called tumours. The cancer cells destroy and replace the healthy tissue around them. Lung cancer can also spread (metastasize) to other parts of the body.
Lung cancer occurs when cells in the lungs become damaged and begin to grow uncontrollably. In most cases, this damage is caused by exposure to nicotine, primarily through smoking. Other environmental factors—such as air pollution, radon gas found in some homes, and other toxic substances—can also contribute. While the risk increases with age, genetics may also play a role in the development of lung cancer. Although it’s less common, lung cancer can still occur in people who have never smoked or been exposed to known toxins.
Lung Cancer:
Quick Facts
- Lung cancer can occur anywhere in the lungs, from the bronchus – which brings air in – to the pleura – the thin tissue that covers the lungs and lines the chest cavity – and anywhere in between.
- There are two main types of lung cancer: non-small cell lung cancer (NSCLC), which accounts for 80-85% of cases, and small cell lung cancer (SCLC), which accounts for the rest.
- Lung cancer is slightly more common in men than in women.
- About half of lung cancer cases are diagnosed at a late stage. At later stages, lung cancer is harder to treat.
- Screening can help find lung cancer early when it is more likely to be treated successfully.
Get Help Now
If you (or a loved one) have been diagnosed with lung cancer and need support, the Lung Health Foundation is here to help. Reach out to our Lung Health Line for free one-on-one guidance from a Certified Respiratory Educator.
Types of Lung Cancer
Depending on where cancer cells are found and how they’re growing and spreading, lung cancer is put in one of two main categories: non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC).
Importantly, the terms “small” and “non-small” have nothing to do with the size of the tumors or the extent of the cancer. They are referring to the kinds of cells found in the cancer and how they look under the microscope.
| Non-small cell lung cancer (NSCLC) | Small cell lung cancer (SCLC) | |
|---|---|---|
How common is it? | This is the most common type of lung cancer, accounting for around 80-85% of cases. | This type of lung cancer is less common, accounting for around 10-15% of cases. |
How quickly does it spread? | NSCLC usually spreads more slowly than other lung cancers. | SCLC is usually more aggressive and can result in larger tumours. |
Major subtypes |
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How it’s staged | Stage 0, I, II, III, or IV. | Limited Stage, Extensive stage |
Treatment options | Chemotherapy, surgery, and radiation therapy are all common treatments for non-small cell lung cancer.
Targeted treatments are an option for some patients. These drugs affect cancer’s ability to grow by targeting specific genes or other factors. To find out if you qualify for any of these treatments, you will need to undergo molecular testing.
Immunotherapy, a kind of treatment that boosts the immune system’s ability to defend against cancer, is an option for some patients. Like targeted treatments, immunotherapies require further testing. | Systemic (whole body) treatments like chemotherapy are more effective in fighting small cell lung cancer than localized treatments like surgery.
Surgery is rare, but may be an option if the cancer has not reached the lymph nodes.
Depending on the stage of the cancer, radiation therapy may be used in combination with chemotherapy (chemoradiation), or could be used to prevent the spread of cancer to the brain.
There are currently no immunotherapy or targeted treatments for SCLC, though current research is investigating the potential for targeted therapies. |
Risk Factors
Smoking, radon, workplace and environmental exposures and genetics are all factors in a person’s risk of developing lung cancer.
Smoking or Second-Hand Smoke
The best action you can take to lower your risk of lung cancer is to live a smoke-free lifestyle. For those who do not smoke, it is as simple as avoiding second-hand smoke and choosing not to start smoking or vaping.
For those who currently smoke, quitting can be a more complex journey – but we’re here to help. It’s never “too late” to quit smoking, even after a lung cancer diagnosis.
With or without a history of smoking, we will be here for you.
Radon
Radon is the second leading cause of lung cancer, and the first leading cause of lung cancer in non-smokers. Radon is a natural radioactive gas that comes from the breakdown of uranium in soil and rock. In enclosed spaces like homes or workplaces, radon can build to unsafe levels. Learn more about radon and how to test for it in your home.
Workplace and Environmental Exposures
Some workers have a higher risk of developing lung cancer. This most often impacts people who work with or around:
- Asbestos
- Diesel engine exhaust
- Crystalline silica
- Welding fumes
- Nickel
- Chromium
- Radon
- Second-hand tobacco smoke
People who work in the following industries have an increased risk for lung cancer:
- Rubber manufacturing
- Iron and steel founding
- Coal gasification
- Coke production
- Chimney sweeping
- Commercial painting
- Roofing and paving
- Industries that use the Acheson process to create silicon carbide
- Firefighting
- Forestry
Genetics
A family history of lung cancer may increase your risk of lung cancer, especially if any of your first-degree relatives that include your parents, siblings, or children, have been diagnosed.
Symptoms of Lung Cancer
In the early stages, lung cancer may have no signs or symptoms at all. That’s why screening is very important for people who are at the highest risk of developing lung cancer.
The most common symptoms of lung cancer include:
- A stubborn cough that won’t go away (which could make it difficult to sleep)
- Coughing up blood or rust-coloured sputum (phlegm)
- Laboured breathing, shortness of breath, or wheezing
- Chest pain (deep in the lungs when lifting, coughing, or laughing)
- Chest infections like pneumonia that are frequent and hard to get rid of
- Fatigue
- Unexplained weight loss and appetite loss
These symptoms are not unique to lung cancer, but it’s important to get checked out if you experience them. Some could be signs of chronic obstructive pulmonary disease (COPD), asthma or other medical conditions.
Screening
Screening for lung cancer is checking for lung cancer in people who do not have symptoms. Most of the time, routine screening for lung cancer is not recommended, except for people who have risk factors such as smoking, workplace or lifestyle exposures, or a family history of cancer.
For example, in Ontario, lung cancer screening can be provided to people at high risk of getting lung cancer. People aged 55-74 with a history of smoking may be referred for screening.
Screening involves a test called a low-dose CT(computed tomography) scan which looks at the lungs to find lung cancer early. The test involves lying on a table that slides in and out of the machine. The machine takes many pictures of the lungs. A computer combines these images to create a more detailed picture of your lungs.
Finding lung cancer early means treatment has a better chance of working. If lung cancer is caught at an early stage, the likelihood of surviving 5 years or more is improved.
Organized lung cancer screening programs are available in Alberta, Quebec, British Columbia, Nova Scotia and Ontario. Projects are also underway in Saskatchewan, Manitoba, New Brunswick and Newfoundland and Labrador to explore starting lung cancer screening programs.
Even though a formal screening program may not be offered in your province or territory, low-dose CT scans can still be ordered by healthcare providers.
Being diagnosed with lung cancer is often life-changing, and emotional distress is common. Understanding the steps and procedures can help you feel more in control, prepare you to advocate for yourself during your treatment.
Your treatment team will consider a number of factors when choosing treatments that will fight your cancer most effectively. They will consider your overall health, age, and personal situation.
The cancer care system can seem overwhelming at first, but we’re here to help you navigate it in a way that makes you feel empowered and supported.
The questions we list here are the top coping questions reported by people with lung cancer. Our answers provide some basic information, but we encourage you to discuss any concerns or questions with your oncologist and other members of your cancer care team.
