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Lung cancer

Lung cancer is the most common cancer in Quebec and Canada and is also the most deadly. The number of Canadians diagnosed with lung cancer in 2018 is 28,600. Among them, there are almost 9,000 Quebecers.

Unfortunately, the risk of lung cancer is inversely related to social and economic status and is notorious for its low survival rate since 17% of Canadians diagnosed with lung cancer survive more than 5 years. In almost 50% of cases, the diagnosis is made when the disease has reached an advanced stage, usually stage IV. It is therefore essential to raise awareness about screening for this cancer.

Lung cancer develops due to abnormal dysregulation and the proliferation of normal cells that make up the lungs. These cells, in addition to destroying healthy tissue, can also disperse from a distance and form extra-pulmonary metastases.

There are 2 main types of lung cancer

Non-small cell lung cancer

It is the most widespread and constitutes 85% of cases of lung cancer. It can progress quickly, and includes 2 main subtypes:

  • Adenocarcinoma: It is the most common form of lung cancer in Quebec and Canada and represents more than 60% of all lung cancers. It is also the most common in women and non-smokers. This cancer subtype is sometimes caused by a genetic defect for which targeted treatments may be available.
  • Squamous cell carcinoma or squamous cell carcinoma: this subtype of cancer accounts for 15 to 20% of cases of lung cancer and is strongly associated with smoking and frequently originates from the proximal respiratory tract (stem and lobar bronchi). In addition, it affects men more than women.

Small cell lung cancer

It is a very aggressive form representing 15 to 20% of lung cancers. Due to its tendency to spread quickly outside the lung, it is difficult to treat and rapidly progressing disease. There are also other types of cancer, including malignant mesothelioma that develops from the lining of the lung (the pleura).

It is aggressive cancer that is mainly found in workers who have worked in close contact with asbestos: Asbestos mine workers, automobile industry, cement industry, construction workers such as electricians, plumbers, carpenter and painter. Given its very long latency period, the disease can appear 20 or even 40 years after exposure.

The lung is also the frequent site of lung metastases, which is to say malignant tumours originating in another part of the body (for example the intestine, the breast, the thyroid), but which spread in the lungs. In these cases, it is an advanced disease that is difficult to treat.


Tobacco exposure: Tobacco is the main cause of this disease. It is estimated that more than 85% of the cases of lung cancer for which tobacco is the main cause. The length of exposure and the number of cigarettes smoked are factors related to smoking that can increase the risk of developing lung cancer. In people who quit smoking, the risk of lung cancer decreases significantly, but still remains; compared to people who have never smoked.

Air quality: Other factors may be associated with the risk of developing lung cancer, such as second-hand smoke, exposure to radon, asbestos, occupational exposure to carcinogens (benzo [a] pyrenes, cadmium, arsenic, etc.), outdoor air pollution, etc. As a result, workers in the rubber manufacturing, iron and steel foundries, chimney sweeping, paving and roofing are at greater risk.

Genetic background and family history: The genetic background and susceptibility of the individual also play an important role in the development of cancer. The risks of lung cancer are therefore increased if a member of your 1st-degree family (father, mother, brother, sister or children) has been diagnosed with lung cancer.

Signs and symptoms

Lung cancer sets in insidiously: it is common that in the early stages of the disease there are few or no symptoms. Its early detection, when it can be most easily cured, is therefore sometimes difficult and even impossible. At first, symptoms are not very noticeable and depend on factors such as the type of cancer, the affected area and the size of the tumour.

The most common and often the first symptom to appear in the presence of an unexplained cough that tends to worsen over time or that simply does not go away. However, other symptoms can be associated with lung cancer:

  • Constant chest pain, worsening with deep breathing
  • Blood in the sputum
  • Shortness of breath
  • Wheezing
  • Change in voice (hoarseness)
  • Weight loss and appetite
  • Great weakness, fatigue
  • Recurrent lung infections

These manifestations are non-specific and can occur in other diseases. Also, when metastases affect other organs, a wide variety of symptoms can appear. For example; during metastases to the brain the patient may present behavioural problems, confusion or even convulsions. Thus, a medical examination is therefore essential.


Lung cancer is the most commonly diagnosed form of cancer. The earlier the diagnosis in the course of the disease, the better the prognosis since the tumor can be completely removed by surgery. Given that it can remain for a long time without the slightest symptom manifesting itself, lung cancer diagnosed early is generally so by chance, that is to say during an examination which aimed to screening for another disease. Chest x-ray is often the first test used in the diagnostic process.

Subsequently, the doctor may suggest, as appropriate, a chest CT scan, a PET scan (positron emission tomography), magnetic resonance imaging (MRI), bronchoscopy, endobronchial ultrasound (EBUS), biopsy and even exploratory lung surgery to investigate and confirm lung cancer.

In addition, certain analyzes carried out on the samples of the tumor (pulmonary biopsy) could make it possible to identify the presence or not of genetic alterations and proteins. This type of analysis can have a significant impact on the proposed treatment plan (targeted therapy and immunotherapy).

Finally, in some cases, additional examinations not mentioned above may also be requested by your doctor or examinations may be repeated during or at the end of treatment in order to monitor the progress of your disease.

The diagnostic process will allow the team of doctors to confirm the presence of lung cancer, its subtype and its stage. For non-small cell lung cancer, the extent of the cancer is determined on a scale of 1 (smaller and smaller tumor) to 4 (larger and larger tumour).


Non-small cell lung cancer

There are different stages of non-small cell lung cancer. These depend on the size of the tumour and its extent. They will also largely determine the choice of treatment.

Stage Description
0 Cancer cells found only in the lining of the airways or in the alveoli
1 A Tumor size <3cm located in the lung 1A1 <1cm; 1A2 <2cm; 1A3 <3cm
B Tumour size> 3cm, but <4cm can also have invaded the pleura, caused the collapse of a lung by obstruction of the bronchus, have invaded the main respiratory tract, but not the region where the trachea divides into the left stem bronchus and right
2 A Tumour size> 4cm, but <5cm or has invaded the pleura, caused a collapsed lung by obstruction of the bronchus, having invaded the main airway, but not the region where the trachea divides into the left main bronchus and right
B Tumour size <or = 5cm that has spread to the lymph nodes near the bronchi
Tumor size> 7cm, but <5cm
A tumour that has invaded the pleura, pericardium, or chest wall
2 or more tumours in the same lung
3 A Tumour size <or = 5cm that has spread to the lymph nodes near the trachea on the same side as the tumour body or in the lymph nodes near the carina
Tumor size> 5cm and:
At least one other tumour in the same lung
The tumour has spread to the lymph nodes near the bronchi
The tumour has invaded the diaphragm, mediastinum, heart, large vessel, esophagus, larynx, trachea, keel or vertebrae.
B Tumour size <or = 5cm and whose cancer has spread to the lymph nodes on the opposite side of the trachea or lung or to the lymph nodes found in the lower part of the neck
C Tumour> 5cm in size and whose cancer has spread to the lymph nodes on the opposite side of the trachea or lung or to the lymph nodes found in the lower part of the neck
There is more than one tumour in different lobes of the same lung and cancer has spread to the lymph nodes on the opposite side of the trachea or lung or to the lymph nodes found in the lower neck
4 A Cancer has spread to the other lung, pleura, pericardium, or a new tumour outside the chest
B Presence of at least 2 tumours developing outside the chest

Small cell lung cancer

The doctor will specify if it is a small or limited stage small cell lung cancer. In such a case, limited will mean that the tumor is present in only one lung and it is also possible that it is present in the lymph nodes present in the chest and near the collarbones. In contrast, the extended stage will mean that the cancer is present in both lungs or lymph nodes, or that it has spread to distant organs (for example, the pancreas).


The choice of treatment will depend on several factors: the subtype of cancer, the clinical stage (extension of the disease) and the physiological state of the patient (age, pulmonary function, general health, etc.), without forgetting his psychological state. The main treatments offered in the case of lung cancer are surgery, radiotherapy, chemotherapy and, more recently, immunotherapy and targeted therapy.

During your meetings with your team of doctors, nurses and pharmacists, they will establish your treatment plan with you. Each of the treatments, whether surgical, medicated or otherwise, constitutes what is called a line of treatment. Your doctor will also specify the order in which they will be performed and whether certain treatments will take place at the same time (for example a patient who would receive radiotherapy while taking chemotherapy).

Surgery: This is an intervention where the surgeon will literally go to remove the tumour, the lobe of the lung or the affected lung. Obviously, it is on the evaluation of several factors that your doctor will be able to suggest surgery as a treatment for your lung cancer. These factors include the extent of cancer and your ability to live with a part or a whole lung afterwards.

Chemotherapy: Treatment using anti-cancer drugs, that is to say, toxic for cancer cells, but which can also be for your body. The goal of chemotherapy is to prevent the division of cancer cells. However, it also prevents the division of healthy cells that multiply quickly like those of the hair and the digestive tract. It is for this reason, among other things, that chemotherapy generally causes several side effects such as hair loss, nausea and vomiting, loss of appetite, etc. Treatments can be given in the hospital or at home and can be done in a variety of ways: swallowing tablets, injections under the skin, injection by vein or other. In most cases, chemotherapy is given in conjunction with another cancer treatment. Side effects vary widely from person to person, and your healthcare team will advise you on the signs to recognize in order to avoid complications.

Radiotherapy: A treatment using radiation, that is to say very powerful x-rays aimed at destroying cancer cells and preventing them from multiplying and developing. Although these rays pass through and damage tissue in your body to reach the tumour, healthy tissue has the ability to regenerate. Since it requires very specialized equipment, this treatment only takes place in certain hospitals. In general, a treatment lasts approximately 20 minutes and 20 to 30 sessions are usually necessary.

Stereotaxic radiotherapy or external radiotherapy: Treatment based on radiotherapy, but where a large quantity of small, strong rays is directed at a specific area of ​​the body. Since this treatment is more targeted, the duration of a session is approximately 60 minutes and 3 to 5 sessions are generally required. This type of treatment can sometimes be used as an alternative to surgery.

Targeted therapy: It is a promising new generation of cancer drugs. This, as its name suggests, targets cancer cells by targeting proteins abnormally expressed by tumour cells only. However, to be effective, these treatments are offered to patients whose tumours have genetic abnormalities detected from the material obtained during the diagnosis of cancer, by a biopsy or bronchoscopy. In certain cases, your healthcare team will have to take new samples in order to be able to repeat these analyzes again.

Immunotherapy: This is a treatment that aims to change the way our immune cells behave. There are several types: some increase the immune capacity to fight cancer while others control and even destroy cancer cells. Since this treatment does not attack healthy tissue, it helps to better control the symptoms and reduce side effects.

Other avenues of treatment are sometimes used via research protocols or clinical trials. Your doctor will advise you if some could apply to you. It is important to realize that the optimal treatment proposed is individualized for each patient according to several factors and often according to a consensus obtained after discussion with a committee of pulmonary tumours bringing together the different specialists involved such as pulmonologists, thoracic surgeons, oncologists, radio-oncologists and pathologists. In more advanced illnesses, supportive or palliative care is offered to the patient.

To learn more about your diagnosis and your treatment plan, we invite you to print the lung cancer fact sheet and have it filled out by your doctor.

Follow up

Since the risk of recurrent lung cancer is higher in the two years after treatment, close monitoring will be done by the medical team who took charge of your treatment plan and by your family doctor. During these follow-ups, the doctor will make an assessment of your state of health based on listening to your lungs and your general condition and may recommend an X-ray of your lungs, blood tests or even a computed tomography if necessary. Never forget to listen to your body.

Advice and prevention

The best chances of recovery are found in patients screened early, eligible for surgery and treated in the early stages of cancer progression (stages 1 and 2). It is therefore essential to listen to the abnormal changes and symptoms experienced. Talk to your doctor about the benefits and risks of screening for lung cancer and ask if it applies to you. Smoking cessation remains the most important aspect in preventing lung cancer. Also, measure the radon content of the air in your home and take measures for the attenuator as well as avoid exposure to products of recognized toxicity, such as asbestos, without adequate protection.

Did you know that

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