Lung Cancer Symptoms and Causes

Lung cancer may not cause noticeable symptoms in its early stages. Some lung cancer cases are found only when imaging tests are performed for another reason. Early-stage lung cancer may also be found through screening in eligible people. When lung cancer symptoms develop, they often affect breathing or cause changes in general health. Common symptoms include a persistent cough, coughing up blood, breathlessness, chest pain and unexplained weight loss.

These signs and symptoms do not necessarily mean you have lung cancer. Infections and other lung conditions can cause similar problems. However, persistent, worsening or unexplained symptoms should receive medical assessment.

What Are the Symptoms of Lung Cancer?

Lung cancer symptoms vary among individuals. They may depend on where the tumour starts, whether it affects nearby structures and whether the cancer has spread to other parts of the body.

The signs and symptoms of lung cancer alone cannot confirm the disease or determine its stage. Some small tumours cause symptoms, while some larger tumours remain unnoticed until imaging tests identify them.
 

Early Symptoms of Lung Cancer

There is no single first symptom of lung cancer. Some people have no symptoms during the early stages. When early lung cancer causes symptoms, they may include:

• A new cough that lasts three weeks or longer
• A persistent cough that becomes worse
• A change in a long-standing cough
• Coughing up blood or blood-stained mucus
• Breathlessness or wheezing
• Chest pain, shoulder pain or back pain
• Repeated chest infections, such as pneumonia
• A hoarse voice
• Ongoing tiredness or weakness
• Loss of appetite
• Unexplained weight loss
• Changes in the fingertips, known as finger clubbing

A persistent cough is common and usually has a cause other than cancer. However, a chronic cough that persists, changes without explanation or occurs with other symptoms should be assessed. Because early lung cancer may resemble infection or another lung condition, persistent changes should not be ignored.

Chest pain, shoulder pain or back pain also has many possible causes. Pain related to lung cancer may be persistent or worsen with coughing, breathing or movement. The location of the pain alone cannot show whether cancer is present. What lung cancer feels like varies, and symptoms cannot diagnose the cause.

Symptoms as Lung Cancer Grows or Spreads

When lung cancer affects nearby tissues or lymph nodes, it may cause increasing breathlessness, persistent hoarseness, difficulty swallowing, facial or neck swelling, or fluid around the lung, called a pleural effusion. Enlarged lymph nodes in the neck may also occur. These symptoms can occur in locally advanced disease, but they are not specific to one stage. Learn more about Stage 3 lung cancer.

When lung cancer spreads to other parts of the body, it may cause bone pain, persistent headaches, weakness, seizures, confusion or yellowing of the skin and eyes. As cancer spreads, symptoms depend on the organs involved. Bone pain may affect the back, ribs or hips. More detailed information belongs in the guide to Stage 4 lung cancer.

When to Seek Medical Care

Arrange a medical assessment if you have:

• A cough lasting three weeks or longer
• A cough that changes or becomes worse
• Blood in your mucus
• Repeated chest infections
• Unexplained breathlessness
• Persistent chest, shoulder or back pain
• Unexplained weight loss or loss of appetite
• Ongoing hoarseness or difficulty swallowing

This is particularly important if you smoke, previously smoked or have other risk factors for lung cancer.

Seek urgent medical care if you:

• Cough up more than a few spots or streaks of blood
• Cough up blood with breathlessness, chest pain, dizziness or a rapid heartbeat
• Develop sudden or severe trouble breathing
• Have facial or neck swelling with breathlessness
• Develop a seizure, confusion or new weakness

Persistent or concerning signs and symptoms require diagnostic assessment rather than screening. Assessment may begin with a medical history, physical examination and chest imaging. Further tests depend on the findings. Read about lung cancer diagnosis and treatment.

What Causes Lung Cancer?

Lung cancer begins when cells in the lungs develop changes in their DNA. DNA contains the instructions that control how cells grow, function and die.

These changes can cause abnormal cells to multiply too quickly and survive when healthy cells would die. These abnormal cells can become cancer cells. The cancer cells may accumulate and form an abnormal growth called a tumour. When cancer spreads, cancer cells can invade nearby lung tissue, damage lung tissue or reach lymph nodes, other organs and other parts of the body.

DNA changes may result from tobacco smoke, environmental or workplace exposure, ageing or random errors during cell division. In some people, no clear cause can be identified.
 

How Smoking Causes Lung Cancer

Cigarette smoking causes most lung cancers and is a major risk factor for developing lung cancer. Tobacco smoke contains carcinogens, which are substances that can cause cancer.

When tobacco smoke enters the lungs, carcinogens can damage the DNA of lung cells lining the airways. The body may repair some early damage. Repeated exposure can cause further changes until cells begin growing without normal control.

The risk of developing lung cancer increases with the number of cigarettes smoked each day and the number of years a person has smoked. Cigars, pipes and other smoked tobacco products also expose the lungs to carcinogens. Quitting smoking reduces the risk, although the risk does not disappear immediately.
 

Lung Cancer in People Who Have Never Smoked

People who have never smoked can develop lung cancer. Possible contributing factors include secondhand smoke, air pollution, radon, workplace carcinogens, previous chest radiation therapy and family history. Often, no single cause is found.

Being a non-smoker does not rule out lung cancer when symptoms persist, or imaging shows an abnormality. Read more about lung cancer in non-smokers.

Risk Factors for Lung Cancer

A risk factor is something that increases the risk of developing lung cancer. Having one or more risk factors does not mean lung cancer will develop. Some people diagnosed with lung cancer have no known risk factors.

Factors that can increase the risk of lung cancer include:

• Smoking. Cigarette smoking is the strongest established risk factor. Risk rises with the amount smoked and the duration of smoking.
• Secondhand smoke. Passive smoking can increase risk.
• Increasing age. Lung cancer becomes more common with age, although younger adults can develop it.
• Workplace carcinogens. Exposure to asbestos, arsenic, diesel exhaust, silica, chromium or nickel may increase risk.
• Radon gas. This natural radioactive gas can cause lung cancer after long-term exposure to high concentrations.
• Air pollution. Long-term exposure to outdoor air pollution is associated with increased risk.
• Previous chest radiotherapy. Radiotherapy for another cancer may increase lung cancer risk later in life.
• Personal history of lung cancer. A person previously treated for lung cancer can develop another primary lung cancer.
• Family history. Risk may be higher when a parent, sibling or child has had lung cancer.
• Long-term lung disease. Chronic obstructive pulmonary disease and pulmonary fibrosis are associated with increased risk.

Asbestos exposure can also cause mesothelioma, a different cancer that develops in the lining around the lungs.

Reducing Lung Cancer Risk

No method can prevent lung cancer completely. Reducing exposure to tobacco smoke and other carcinogens can lower the risk of lung cancer.

Steps that may help include:

• Do not start smoking.
• If you smoke, seek support for quitting smoking. Counselling, nicotine replacement or prescribed medicines may help.
• Avoid second-hand smoke where possible.
• Follow workplace safety procedures and use protective equipment correctly.
• Reduce exposure to known cancer-causing substances.
• Address radon exposure where local testing or building assessments indicate a concern.
• Avoid high-dose beta-carotene supplements for lung cancer prevention, particularly if you smoke or previously smoked.

A balanced diet and regular physical activity support general health, but they cannot guarantee that lung cancer will be prevented.

Lung Cancer Screening Is for People Without Symptoms

Lung cancer screening uses a low-dose CT scan to look for cancer in selected higher-risk people who do not have symptoms. Current lung cancer screening guidelines base eligibility on factors such as age, smoking history and whether a person can undergo further assessment and treatment if needed.

Screening has possible benefits and limitations, including false-positive findings and follow-up tests for nodules that are not cancer. Learn more about eligibility and shared decision-making for lung cancer screening in Singapore.

Do not wait for a screening appointment if you have persistent respiratory symptoms, coughing up blood or another warning sign. These symptoms require diagnostic assessment.

Thoracic Surgical Assessment at Neumark

Neumark Lung & Chest Surgery Centre specialises in minimally invasive thoracic surgery with a multidisciplinary approach led by Dr Harish Mithiran, senior consultant thoracic surgeon at Gleneagles and Mount Alvernia hospitals.

A thoracic surgical assessment may be appropriate when imaging shows a suspicious lung lesion, a biopsy confirms potentially operable lung cancer, or the treating team recommends reviewing surgical options. Patients can contact Neumark to discuss an appropriate assessment.