Despite these problems, coughing actually serves a very valuable and useful purpose. Coughing is a protective action, helping the lungs clear out potential germs or harmful objects.

Sometimes, however, that cough is not linked to a cold or infection and can linger for weeks to months at a time. This may lead people to wonder or worry that their cough is a sign of something more serious, such as lung cancer.

This article takes a look at the connection between coughing and lung cancer, including when someone should see a doctor.

Coughing and lung cancer

A cough associated with lung cancer may be either dry or wet.

Not every cough signifies the presence of lung cancer. However, many people do complain of a chronic cough or a “cough that just won’t go away” at the time of their diagnosis.

If a cough is associated with other symptoms, such as those in the list below, it warrants a trip to the doctor to get checked out:

• coughing up blood or rust-coloured phlegm
• shortness of breath
• chest pain

A cough that is associated with lung cancer can be either dry or wet. It can occur at any time, and even be so severe that it interferes with sleep at night.

Lung cancer symptoms

There are many symptoms other than persistent or worsening coughing that is associated with lung cancer. Some of these symptoms include:

• ongoing chest pain
• coughing up blood
• shortness of breath
• wheezing or hoarseness of the voice
• problems swallowing
• loss of appetite
• losing weight
• Fatigue and tiredness
• frequent lung infections, such as pneumonia or bronchitis

Causes of coughing

Allergies such as hay fever may cause short-term coughing. A long-term cough that does not clear up a few weeks, or that gets worse, may have a more serious cause.

There are many reasons why someone might be coughing. A short-term cough can be caused by:

• an infection, such as a cold, pneumonia, or bronchitis
• an allergy, such as hay fever
• inhaled dust, smoke, or debris
• a long-term respiratory condition, such as asthma or COPD

Sometimes, a short-term cough can develop into a chronic or a persistent cough. When this happens, it may be caused by one of the following factors:

• Long-term respiratory infection, such as chronic bronchitis or pneumonia.
• Asthma, which causes shortness of breath, tightening of the chest, and wheezing.
• Allergies, such as hay fever.
• Smoking. Chronic coughing in a smoker is also known as a “smoker’s cough” and is the result of smoke and other debris irritating the airways.
• Bronchiectasis, which is a widening of the airways in the lungs.
• Postnasal drip, which is mucus dripping down the throat and triggering a cough. This is usually associated with a cold or allergy.
• Gastroesophageal reflux disease (GERD), where stomach acid flows back into the food pipe. The throat gets irritated by the acid and triggers a cough.
• Medications, such as ACE inhibitors, which are used to treat high blood pressure and heart disease.

When to see a doctor

Most coughs clear up within a few days to a few weeks.

It is important to see the doctor if the cough is persistent or occurs along with other symptoms, such as coughing up blood or chest pain.

Seeing a doctor promptly can help to determine the cause of a cough and ensure that nothing more serious is going on.

Diagnosis

Firstly, the doctor will take a thorough medical history and perform a physical exam. In addition to asking about family and personal medical history, the doctor will ask about the history of coughing, shortness of breath, and other symptoms.

During the physical exam, the doctor will listen to the heart and lungs, and look for other potential causes of the coughing, such as signs of an infection or postnasal drip.

Depending on the findings from the history and physical, the doctor may order additional testing. This may include imaging tests, such as:

• a chest X-ray
• CAT scan
• PET scan
• MRI

If lung cancer is suspected based on these results, the doctor will likely want to take a biopsy of the suspicious cells. A doctor can do this by passing a needle into the lung tissue through the skin.

Another way is by bronchoscopy, where a small tube is inserted down the nose and into the lungs. A small sample is removed through the tube and analyzed.

A specialist called a pathologist will look at the cell samples under the microscope to determine if there is cancer. If cancer is present, they will also work out the type, and how far it has advanced.

If lung cancer is diagnosed, the doctor may want to order additional testing to see if it has spread beyond the lungs.

Researchers have also found some genetic markers that can impact how a cancer behaves. This includes whether it is aggressive or spreads quickly, or is responsive to certain hormones.

Some doctors will order genetic testing to look for these genetic markers. Positive results can sometimes help with making treatment decisions, as there are new medications that can be more effective than traditional therapies.

Treatment options

Chemotherapy is a common treatment option for lung cancer, although complete removal of the tumor is usually preferable.

The best treatment for lung cancer is complete removal of the tumor and unhealthy cells surrounding it.

Removal is usually only an option when the growth is small and contained, or has only spread to the nearby tissues.

Radiation or chemotherapy is sometimes also given to ensure that all of the cancerous cells have been removed or destroyed.

Once a tumour has spread significantly, it may no longer be removable or curable. The doctor may recommend radiation or palliative care to prevent further complications and treat symptoms.

New targeted therapies may be more successful in certain groups of people or with particular types of cancers. These include female non-smokers or carriers of certain genetic markers.

The doctor can help work out whether someone may benefit from these types of treatments.

Outlook

The outlook for someone diagnosed with lung cancer depends on the stage of cancer when it is diagnosed.

In general, someone with small cancer that has not spread to other parts of the body has a much better outlook than someone who has an aggressive form of cancer that has spread.

Early diagnosis and treatment are very important in increasing the odds of surviving lung cancer. There is no screening test, which can make early detection more difficult.

The best way to prevent lung cancer is to live a healthful lifestyle and avoid cigarette smoke whenever possible. In addition to not smoking, or quitting smoking, avoiding secondhand smoke is essential.

Someone with a high risk of developing lung cancer, based on either family history or history of smoking, should discuss any unusual symptoms with their doctor as soon as possible. These symptoms include a persistent cough that occurs with chest pain, shortness of breath, or blood.