What Are the Warning Signs of Lung Cancer?

Common lung cancer symptoms are a new cough or one that will not clear, chest pain, coughing up blood or bloody mucus, and unexplained weight loss. Early lung cancer often causes none of these. This page is general information from public health sources, not a diagnosis.

These symptoms have many causes, and most are not cancer. Only a clinician can tell what is behind them, usually with an imaging test.

What are the symptoms of lung cancer?

Health Canada’s page on tobacco and lung cancer lists coughing, chest pain, unexplained weight loss, and spitting up blood or bloody mucus.

HealthLinkBC gives a longer list:

• a new cough, or a cough that does not go away
• chest, shoulder or back pain that does not go away
• new wheezing, shortness of breath or hoarseness
• swelling in the neck and face, or difficulty swallowing
• weight loss and loss of appetite
• increasing fatigue and weakness
• recurring respiratory infections such as pneumonia

Several of these overlap with COPD, chronic bronchitis and ordinary chest infections. Our guides to COPD symptoms and smoker’s cough cover the overlap, and the lung diseases overview puts the main conditions side by side.

Why does early lung cancer often have no symptoms?

Our sources do not explain the mechanism, but they point to the fact. Screening programs in British Columbia, Alberta and Nova Scotia are built for people without symptoms. Nova Scotia Health describes screening as looking for cancer before there are warning signs or symptoms. HealthLinkBC says lung cancer is usually first found on a chest X-ray or CT scan.

For a long-term smoker, a persistent cough is easy to dismiss as part of the habit. That is one reason a cough that changes, or lasts, deserves a conversation with a clinician.

How much lung cancer is linked to smoking?

Health Canada estimates that 72% of lung cancer cases in Canada are caused by smoking, and says smokers are about 25 times more likely to die from lung cancer than people who have never smoked. Its general page on smoking and your body gives a different figure, so see which cancers are linked to smoking for how the numbers differ.

Not everyone with lung cancer has smoked, and not everyone who smokes gets it. Smoking history is a risk factor, not a verdict.

When should I see a doctor or nurse practitioner?

HealthLinkBC advises calling your doctor to ask whether you should be seen if you:

• have a cough that lasts longer than 4 weeks
• lose weight for no clear reason
• have increasing fatigue for no apparent reason

Call your doctor promptly for swelling of the neck and face, or for rapid, shallow breathing or wheezing even at rest. Call 9-1-1 or your local emergency number for new or sudden difficulty breathing or coughing up a lot of blood.

Is there lung cancer screening in Canada?

Some provinces run programs for people at high risk who have no symptoms. Rules are set province by province, so what applies in one does not apply in another. This is what we confirmed on official pages on 4 November 2026:

Province	Age	Smoking history	Other
British Columbia (BC Cancer)	55 to 74	Significant history of regular tobacco use, current or former	Primary care provider required
Alberta (Screening for Life)	50 to 74	Current smoker, or quit after a long history	High risk
Nova Scotia (Central and Eastern Zones)	50 to 74	Smoked daily for at least 20 years	Not everyone who meets the criteria qualifies for a CT scan

Screening is not a way to investigate symptoms. If you already have a cough, chest pain or blood in your mucus, you need a medical assessment first. The lung screening eligibility checker has the full comparison, phone numbers and the national task force guideline, and the pack-year calculator helps you work out your history.

What does quitting change?

Health Canada says that ten to fifteen years after quitting, the risk of lung cancer is about half that of someone who keeps smoking, and that quitting sooner gives a greater long-term benefit. For people who already have early-stage lung cancer, it says quitting can slow the disease and substantially lower the risk of death.

If you want help stopping, the quit smoking hub and the list of free quit help by province are the places to start.

What we could not confirm

We did not find an official page we could open that states current screening rules for Ontario, Quebec, Manitoba, the remaining Atlantic provinces or the territories, or Saskatchewan’s smoking-history criteria. Their absence from the table does not mean they have no program. We also have no official source for why early disease is silent, so we have not offered an explanation.