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Lung cancer

In the 19th century, lung cancer was relatively rare. In the 20th century, it became a common disease, and is nowadays the leading cause of cancer-related mortality and morbidity.

Lung cancer is a disease caused by the chaotic development of abnormal cells in the lungs. These abnormal cells no longer fulfill the functions of normal cells; in fact, as they multiply, the cancerous cells destroy healthy lung tissues:

  • Abnormal cells.
  • Spread of the cancerous cells.


Tobacco is the number one cause of this disease. Tobacco smoke, and especially cigarette smoke, is recognized as the leading cause of lung cancer. Inhaling secondhand smoke also increases the risk of developing lung cancer, as carcinogens are present in the sidestream smoke inhaled by non-smokers or people in close proximity to smokers.

When cigarette smoke is combined with exposure to certain toxic products in the work environment, such as asbestos, radioactive dust, arsenic, or certain plastics, the risk of developing lung cancer takes on alarming proportions. Air pollution, motor vehicle emissions and industrial polycyclic aromatic hydrocarbon waste are known carcinogen sources. Lung cancer sometimes occurs in people who have never smoked or never worked with substances recognized as carcinogenic. In some cases, heredity may play a significant role.

Signs and symptoms

Lung cancer is an insidious disease. Detecting it early, when it can be most easily treated, is a difficult task. At first, the symptoms are hardly apparent, depending on the area affected, the size of the tumor, the extent of the obstruction. Sometimes there are no symptoms at all, and the cancer is only discovered following a mucus (sputum) analysis or lung X-ray.

The signs include:

  • a worsening cough;
  • a cough characterized by mucus containing traces of blood;
  • shortness of breath and chest pains.

Any combination of these symptoms in people with a long history of smoking should be viewed as a warning and calls for a medical examination. Some people will also notice symptoms said to be general : change in voice, loss of weight and appetite, not to mention considerable weakness.


A chest X-ray may reveal a growth (tumor) in the lungs. Other clinical methods used to investigate for lung cancer include fresh sputum cytology, bronchoscopy using a flexible fiberscope, lung scintigraphy, CAT scans, proton magnetic resonance, biopsies and even investigative lung surgery.

GIVING UP SMOKING REMAINS BY FAR THE MOST EFFECTIVE PREVENTION METHOD. Cancer prevention is becoming one of the surest ways of guaranteeing a good quality of life. To help prevent lung cancer, people should improve their prevention methods and personal hygiene practices. Avoid secondhand smoke,adopt a balanced diet that is rich in fruit and preferably green vegetables, lead a balanced life and sleep well.


Lung cancer can be treated in a variety of ways : surgery, radiation therapy, chemotherapy, administered individually or combined. Treatment depends on the cell type, the clinical stage (progression of the disease) and the physiological condition of the patient, not to mention his/her psychological state. Surgery offers the best chances for recovery but unfortunately for some people, the lung cancer is detected too late and the tumor is inoperable; hence the importance of prevention.

Tips and prevention

The best protection anyone can adopt is to avoid smoking. Do not hesitate to use the means or methods at your disposal to quit smoking. If you notice any unusual symptoms, like a worsening cough, traces of blood in the sputum or repeated respiratory infections, make arrangements for a medical examination as soon as possible.

Did you know that

The Quebec Lung Association offers direct services to the population. For more information, visit our Patient Resources section.