Lung cancer is the growth of abnormal cells inside the lung. These cells divide and grow more quickly than normal cells and form a tumour, which is a cluster of cells. If cancer starts in the lungs, it is called primary lung cancer. It can also spread (metastasize) to other parts of the body.

Lung cancers are divided into non-small cell lung cancer and small cell lung cancer, based on where cancer started. Other types of lung cancers are mesothelioma and a carcinoid tumour.


Lung cancer is much easier to treat when it is detected and diagnosed early. However, many people do not experience symptoms until the disease has progressed to a later stage (see Screening, below).  Symptoms can be different for each person.  Some common symptoms include: 

  • a cough that does not go away or gets worse
  • coughing up blood or rust-colored sputum (spit or phlegm)
  • chest pain that is often worse with deep breathing, coughing, or laughing
  • hoarseness
  • loss of appetite
  • unexplained weight loss
  • shortness of breath
  • feeling tired or weak
  • infections such as bronchitis and pneumonia that don’t go away or keep coming back
  • new onset of wheezing
  • headaches
  • bone pain or fractures
  • blood clots

Speak to your healthcare provider if you experience any of these symptoms. Discuss your risk factors of developing lung cancer and determine with your healthcare provider if further lung cancer screening is best. Many lung cancer symptoms are like other conditions and diseases. However, ensuring you have the proper diagnosis is imperative and can be lifesaving. 


  • Smoking is the leading cause of lung cancer. However, not everyone that develops lung cancer smokes. Exposure to second-hand smoke also increases your risk. Quitting smoking is the best thing you can do for your overall health and to prevent lung disease, including lung cancer.
  • Radon is the second leading cause of lung cancer which is why it is so critical to test for radon in your home. Radon is a radioactive gas that comes from the natural breakdown of uranium. Those who smoke and are exposed to high levels of radon are at even greater risk of developing lung cancer. 
  • Personal history of cancer or other lung diseases, such as COPD, pneumonia, and tuberculosis can also increase your risk of developing lung cancer. Lung cancer is more common in people who have been previously diagnosed with other cancers such as the mouth or throat.   
  • Genetics could increase your risk of developing lung cancer. If others in your family have had lung cancer, make sure to tell your healthcare provider.
  • Hazardous chemicals exposure poses a lung cancer risk. Working with materials such as asbestos, uranium, arsenic, cadmium, chromium, nickel, and some petroleum products is especially dangerous.
  • Pollutants in the environment can increase the risk of lung cancer. Air pollution from motor vehicles, factories, and power plants contain microscopic particles, nitrogen oxides, diesel exhaust, benzene, and polycyclic aromatic hydrocarbons which are harmful to the lungs, increasing the risk of lung cancer. 


Some early cancers have symptoms that are noticeable, but that is not always the case. Screening is the use of tests or exams to find a disease in people that might not have noticeable symptoms.

In lung cancer, early detection is everything. The sooner lung cancer is diagnosed, the better the opportunity for curative treatment.

The Canadian Task Force on Preventive Health Care recommends screening for lung cancer with three consecutive annual low-dose computed tomography (CT) scans in high-risk individuals (i.e., adults aged 55-74 years who currently smoke or quit less than 15 years ago, with a smoking history of at least 30 pack-years.) A pack year is defined as the average number of packs smoked daily multiplied by the number of years of smoking.

Hospitals and clinics across the country have teams and the expertise to conduct lung cancer screening. Speak to your healthcare provider to get a referral.


Coming to a diagnosis of lung cancer usually starts a visit to your healthcare provider, who will take a medical history, do a physical exam, and arrange certain tests. They may then refer you to a specialist or order further tests to check for lung cancer or other health problems. 

Medical History and Physical Exam

During a medical history, your healthcare provider will ask you questions about yourself to learn about any unusual symptoms that might be related to lung cancer as well as any possible risk factors for lung cancer. 

During a physical exam your healthcare provider will look for signs of lung cancer or other health problems.

Initial tests

Imaging tests are usually used to rule out or diagnose lung cancer and many of these same tests are used to find out the stage of cancer (how far the cancer has spread). Your healthcare provider may also order other tests to check your general health and to help plan your treatment, such as:

  • Chest Radiography (x-ray): This is often one of the first tests done to look for any abnormal areas in the lungs. 
  • High Resolution Computed Tomography (HRCT) scan: Also known as a CT scan, this test uses x-rays to make detailed cross-sectional images of your body. Instead of taking 1 or 2 pictures, like a regular x-ray, a CT scanner takes many images, and a computer combines them to show a slice of the part of your body being studied. A CT scan is more likely to show lung tumors than routine chest x-rays and can also show the size, shape, and position of any lung tumors. 
  • Positron Emission Tomography (PET) Scan: During a PET scan, a slightly radioactive form of sugar (known as FDG) is injected into the blood and collects mainly in cancer cells.
  • Magnetic Resonance Imaging (MRI) Scan: Like CT scans, an MRI shows detailed images of soft tissues in the body. An MRI uses radio waves and strong magnets instead of x-rays. MRI scans are most often used to look for possible spread of lung cancer to the brain or spinal cord.
  • Bone Scan: During a bone scan, a small amount of low-level radioactive material is injected into the blood and collects mainly in abnormal areas of bone. A bone scan can help show if a cancer has spread to the bones. However, this test isn’t needed often because PET scans can usually show if cancer has spread to the bones.

Tests to Diagnose Lung Cancer

Symptoms and the results of certain tests may strongly suggest that a person has lung cancer, but the actual diagnosis is made by looking at lung cells in the lab. 

The cells can be taken in the following ways:

  • Sputum Cytology:  A sample of sputum (mucus you cough up from the lungs) is looked at in the lab to see if it has cancer cells. This test is more likely to help find cancers that start in the major airways of the lung, such as squamous cell lung cancers. It might not be as helpful for finding other types of lung cancer. If your healthcare provider suspects lung cancer, further testing will be done even if no cancer cells are found in the sputum. 
  • Thoracentesis: If fluid has collected around the lungs (called a pleural effusion), some of the fluid can be removed to find out if it is caused by cancer spreading to the lining of the lungs (pleura) or another condition such a heart failure or an infection. Other tests of the fluid are also sometimes useful in telling a malignant (cancerous) pleural effusion from one that is not. If a malignant pleural effusion has been diagnosed and is causing trouble breathing, a thoracentesis may be repeated to remove more fluid which may help a person breathe better.
  • Biopsy: Two types of biopsies may be taken:
    • During a needle biopsy, a hollow needle is used to get a small sample from a suspicious area (mass). An advantage is that they don’t require a surgical incision. The drawback is that they remove only a small amount of tissue which may not be enough to both make a diagnosis and perform more tests on the cancer cells that can help determine appropriate anticancer drugs.
    • During a surgical biopsy a surgeon takes a sample of the lung tissue by making small cuts in your chest. A pathologist then looks at the cells through a microscope to determine the abnormality. This procedure is done under general anesthetic, so you will be asleep and won’t feel anything.


Treatment for lung cancer will vary depending on the type of lung cancer and the stage. Treatment options may include chemotherapy, surgery, radiation therapy, immunotherapy, and targeted treatments. 

Some people may need supplemental oxygen as part of their lung cancer treatment if the oxygen levels in the blood are low. Home oxygen is not a cure, but it can help improve your quality of life. If your healthcare provider prescribes you home oxygen, it is very important to treat it like any other medication prescription (e.g. all day, at night, or during exertion).