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Lung cancer


In Quebec, lung cancer is the leading cause of death from cancer in both women and men. The Canadian Cancer Society estimates that 8,900 new cases of lung cancer were diagnosed in Quebec in 2019 (29,400 in Canada as a whole) and that 6,600 deaths from this disease were recorded (21,000 in Canada). Quebec is among the Canadian provinces with the highest age-standardized incidence and mortality rates for this type of cancer.

There are two main types of lung cancer. They progress differently and are treated in different ways:

  • Small cell lung cancer (SCLC) accounts for 15-20 % of all lung cancers. This type of cancer usually grows rapidly, with a strong tendency to metastasize.
  • Non-small cell lung cancer (NSCLC) accounts for 80-85 % of all lung cancers. Adenocarcinomas or squamous cell carcinomas make up the majority of cancers in this category.

Causes of lung cancer

Exposure to tobacco

Tobacco is the primary source of this disease. It is estimated that tobacco is the main cause of over 85 % of lung cancer cases. The length of exposure and the quantity of cigarettes smoked increase the risk of developing lung cancer. For people who quit smoking, the risk of lung cancer decreases significantly over the years, but is still higher than for people who never smoked.

Air quality

Various toxic substances can contaminate the air we breathe. Exposure to some of these pollutants plays an important role in developing lung cancer. These pollutants are as follows:

  • asbestos;
  • radon (a radioactive gas naturally present in the ground);
  • carcinogenic substances such as silica, cadmium, arsenic, chromium, etc. Workers in rubber manufacturing plants; iron and steel foundries; chimney sweepers, asphalt paving and roofing companies are more at risk;
  • second-hand smoke.

Personal/family history and genetic background

  • People who have had lung cancer in the past are more likely to develop lung cancer again.
  • Some lung diseases can scar the lungs and increase the risk of developing lung cancer:
    • Chronic obstructive pulmonary disease (COPD), which is characterised by long-term damage to the lungs, is often caused by smoking
    • Emphysema and chronic bronchitis, which are types of COPD;
    • Tuberculosis, which is a lung infection caused by the tuberculosis bacillus;
    • Lung infection caused by Chlamydophila pneumoniae.
  • The risk of lung cancer is slightly higher if a member of your immediate family (father, mother, brother, sister or children) has been diagnosed with lung cancer.

Radiation exposure

People who have received chest radiotherapy for cancers such as Hodgkin’s lymphoma or breast cancer, have an increased risk of developing other types of cancer, including lung cancer. These people are at even greater risk if they smoke.

People at risk

Some people are more likely than others to get lung cancer. In general, people at higher risk of lung cancer smoke or have smoked cigarettes daily for at least 20 years continuously or on and off.

If you are between 55 and 74 years old and smoke or smoked for at least 20 years, you may be at higher risk of developing lung cancer. See the Lung cancer screening demonstration project page.


Lung cancer usually develops without any noticeable symptoms, especially early in the disease. If symptoms do occur, they may include :

  • a cough that gets worse and lasts longer;
  • the onset or worsening of shortness of breath;
  • wheezing;
  • constant chest pain that increases with breathing or coughing;
  • blood in the sputum that is coughed up;
  • bronchial infections (bronchitis, pneumonia) that persist or recur despite antibiotics
  • hoarseness or a change in voice;
  • unexplained weight loss and loss of appetite;
  • extreme fatigue.
General notice

Seek medical advice

If you have been experiencing any of the above symptoms for some time, you should see a doctor. However, these symptoms are not necessarily caused by cancer.

Protection and prevention

Healthy lifestyle habits

The best way to reduce your risk of lung cancer is to adopt healthy lifestyle habits, including:


Lung cancer screening aims to detect cancer at an early stage, before signs and symptoms of the disease appear. This improves the chances of successful treatment. Screening is aimed at people who have a high risk of developing lung cancer.

Lung Cancer Screening Demonstration Project

The Lung Cancer Screening Demonstration Project is aimed at people aged 55-74 who are at high risk of developing lung cancer, but who have no symptoms of lung cancer or any serious illness. The demonstration project started on June 1, 2021.


When someone is diagnosed with lung cancer, a special oncology team will work out a personalized treatment plan with them. This treatment plan may vary depending on different factors, such as the type and stage of the cancer, and the person’s health status. The treatment plan will also take into account the wishes and concerns of the person with cancer, as well as their family. The treatment plan may include one or a combination of treatments.

For a smoker, stopping is the first treatment and an essential part of quality cancer care. The decision to quit smoking when diagnosed with cancer is one of the best things a person can do to improve the treatment and their quality of life.

Last update: May 31, 2021


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