Lung cancer is one of the most serious forms of cancer affecting people around the world. It develops when abnormal cells in the lungs begin to grow uncontrollably and can eventually invade nearby tissues or spread to other parts of the body.

Although smoking is the leading risk factor, lung cancer can also affect people who have never smoked. Exposure to secondhand smoke, radon, air pollution, workplace chemicals and certain other factors can increase the risk.

Understanding lung cancer symptoms, causes, risk factors, diagnosis, stages and treatment options can help people recognize concerning changes earlier and seek appropriate medical care.

What Is Lung Cancer?

Lung cancer occurs when abnormal cells in the lung begin multiplying without the normal controls that regulate healthy cells.

Over time, these abnormal cells can form a tumor. Some lung cancers remain relatively localized, while others can grow into surrounding tissues or spread through the bloodstream or lymphatic system to distant organs.

The two major categories are non small cell lung cancer and small cell lung cancer. Non small cell lung cancer accounts for most cases, while small cell lung cancer is less common and generally grows and spreads more quickly. World Health Organization+1

How Common Is Lung Cancer?

Lung cancer represents a major global health problem. According to the World Health Organization, approximately 2.5 million people developed lung cancer in 2022, while around 1.8 million people died from the disease. Lung cancer was the leading cause of cancer death worldwide that year. World Health Organization

More recent international cancer estimates continue to show that lung cancer is among the world’s most frequently diagnosed cancers and remains the leading cause of cancer related death globally. IARC

The exact risk and statistics vary between countries because smoking patterns, air pollution, occupational exposure, access to screening and access to medical treatment differ.

Main Types of Lung Cancer

Non Small Cell Lung Cancer

Non small cell lung cancer, often abbreviated as NSCLC, is the most common type.

It includes several important subtypes.

Adenocarcinoma

Lung adenocarcinoma is a common form of NSCLC. It can occur in smokers and people who have never smoked.

It often develops in the outer areas of the lungs and may be associated with specific genetic changes that can influence treatment.

Squamous Cell Carcinoma

Squamous cell lung cancer often develops in the larger airways and has a strong association with tobacco smoking.

Large Cell Carcinoma

Large cell carcinoma is a less common type of NSCLC. It can develop in different areas of the lung and may grow relatively quickly.

Small Cell Lung Cancer

Small cell lung cancer, or SCLC, is less common than NSCLC but can be particularly aggressive.

It frequently spreads early, which is why doctors usually approach diagnosis and treatment differently from non small cell lung cancer. Cancer.gov+1

What Causes Lung Cancer?

There is usually not one single cause of lung cancer. Instead, cancer develops after genetic and environmental changes cause lung cells to grow abnormally.

Smoking

Tobacco smoking is the most important preventable risk factor for lung cancer.

Cigarettes contain thousands of chemicals, including many substances known to cause cancer. The risk generally increases with the amount and duration of smoking.

Importantly, even people who smoke relatively small amounts can have an increased risk. Quitting smoking lowers the risk over time. CDC

Secondhand Smoke

People who do not smoke can still be exposed to carcinogenic substances by breathing secondhand tobacco smoke.

Long term exposure can increase the risk of lung cancer. Creating smoke free homes, vehicles and workplaces can reduce unnecessary exposure.

Radon

Radon is a naturally occurring radioactive gas that can accumulate inside buildings.

It cannot be seen, smelled or tasted. Long term exposure to elevated radon levels can increase the risk of lung cancer, including among people who have never smoked. CDC

Air Pollution

Long term exposure to outdoor and indoor air pollution has also been associated with an increased risk of lung cancer.

Reducing exposure to polluted air is therefore an important part of broader lung health and cancer prevention strategies. World Health Organization

Workplace Exposure

Certain occupational substances can increase lung cancer risk.

Examples include:

Asbestos

Silica

Arsenic

Diesel exhaust

Chromium compounds

People working in industries where these substances may be present should follow appropriate workplace safety measures. CDC

Family History and Genetics

Having a close family member with lung cancer may increase a person’s risk.

Genetic susceptibility may contribute to risk in some families. However, family history does not mean that a person will definitely develop lung cancer.

Can Lung Cancer Occur in Someone Who Never Smoked?

Yes.

Never smokers can develop lung cancer.

Smoking is responsible for a large proportion of lung cancers, but other factors can also contribute, including secondhand smoke, radon, air pollution, occupational exposures and genetic factors. World Health Organization+1

This is an important reason why persistent or unusual respiratory symptoms should not automatically be dismissed simply because someone has never smoked.

Symptoms of Lung Cancer

One of the challenges with lung cancer is that early disease may cause few or no obvious symptoms.

When symptoms develop, they may include:

Persistent cough
A cough that becomes worse over time
Coughing up blood
Chest pain
Shortness of breath
Wheezing
Persistent tiredness
Unexplained weight loss
Repeated lung infections
Swollen lymph nodes in the chest or neck

Some symptoms can also appear when lung cancer spreads outside the lungs. The symptoms then depend on which organs are affected. CDC+1

It is important to remember that these symptoms do not automatically mean cancer. Many respiratory infections and other medical conditions can cause similar problems.

However, symptoms that persist, worsen or occur together should be evaluated by a healthcare professional.

When Should You See a Doctor?

Consider seeking medical evaluation if you have a persistent cough, unexplained weight loss, coughing up blood, continuing chest discomfort, worsening breathlessness or repeated respiratory infections.

You should not wait for severe pain before seeking medical attention. Cancer can sometimes develop without causing significant pain in its early stages. Cancer.gov

Coughing up blood should always be taken seriously and medically assessed.

How Is Lung Cancer Diagnosed?

Diagnosing lung cancer usually involves several steps.

Medical History and Physical Examination

A doctor may ask about:

Smoking history

Occupational exposure

Family history

Respiratory symptoms

Previous medical conditions

A physical examination may also provide clues about the person’s health.

Chest Imaging

Doctors may use imaging tests to look for abnormalities in the lungs.

These may include:

Chest X ray

Computed tomography scan

Magnetic resonance imaging in selected situations

A CT scan can provide much more detailed information about lung abnormalities than a standard chest X ray.

Bronchoscopy

During a bronchoscopy, a doctor uses a thin flexible instrument to examine the airways.

If an abnormal area is found, tissue or fluid samples may sometimes be collected.

Biopsy

A biopsy involves obtaining a sample of tissue so that it can be examined under a microscope.

A biopsy is often essential for confirming the diagnosis and determining the specific type of lung cancer.

Molecular Testing

Modern lung cancer care increasingly uses molecular testing.

Tumor tissue may be tested for particular genetic changes and biomarkers that can help doctors select targeted treatments or other therapies.

This is particularly important for many patients with advanced non small cell lung cancer. World Health Organization

What Does Lung Cancer Staging Mean?

After lung cancer has been diagnosed, doctors determine its stage.

Staging describes how extensive the cancer is and whether it has spread.

For non small cell lung cancer, stages are generally described from stage 1 through stage 4.

Stage 1

The cancer is relatively localized and has not spread extensively.

Stage 2

The cancer is larger or has involved certain nearby structures or lymph nodes.

Stage 3

The cancer has spread more extensively within the chest or to specific nearby lymph nodes.

Stage 4

The cancer has spread to distant parts of the body. This is called metastatic lung cancer.

Small cell lung cancer is commonly categorized differently, using terms such as limited stage and extensive stage.

The exact staging system is more complicated than these simple descriptions, and doctors use imaging, biopsy results and other findings to determine the stage.

What Does Metastatic Lung Cancer Mean?

Metastasis means that cancer cells have spread from the original tumor to another part of the body.

Lung cancer may spread to organs such as the:

Brain
Bones
Liver
Adrenal glands
Other areas of the lungs

Symptoms of metastatic disease depend on where the cancer has spread.

For example, cancer involving the brain may cause neurological symptoms, while cancer involving the bones may cause persistent bone pain.

Treatment of Lung Cancer

Treatment depends on several factors, including:

Cancer type

Cancer stage

Molecular characteristics

Overall health

Location of the tumor

Previous treatments

Patient preferences

Modern lung cancer treatment may involve one treatment or a combination of several approaches.

Surgery

Surgery can be an important treatment for selected patients, particularly when lung cancer is detected at an earlier stage.

Depending on the situation, a surgeon may remove part of the lung or an entire lung.

Procedures can include:

Wedge resection

Segmentectomy

Lobectomy

Pneumonectomy

The appropriate operation depends on the location and extent of the cancer and the person’s overall health. World Health Organization

Radiation Therapy

Radiation therapy uses high energy radiation to destroy or control cancer cells.

It may be used:

To treat certain early lung cancers
After or around surgery in selected situations
Together with other treatments
To control symptoms caused by advanced cancer

Radiation can also be useful for treating certain areas where cancer has spread.

Chemotherapy

Chemotherapy uses medicines that kill cancer cells or prevent them from multiplying.

It may be used for small cell lung cancer and for selected patients with non small cell lung cancer.

Chemotherapy may also be combined with surgery, radiation therapy, immunotherapy or targeted treatment depending on the cancer.

Targeted Therapy

One of the major advances in lung cancer treatment has been the development of targeted therapies.

These medicines are designed to interfere with specific molecular abnormalities that help cancer cells grow.

Because targeted therapy works against particular changes, molecular testing of the tumor can be extremely important.

Not every patient has a genetic change that can be treated with an available targeted medicine.

Immunotherapy

Immunotherapy helps the immune system recognize and attack cancer cells.

It has become an important treatment option for several forms and stages of lung cancer.

The choice of immunotherapy depends on factors such as the cancer type, stage and biomarker results.

Palliative and Supportive Care

Palliative care is not limited to the final stage of life.

It focuses on improving comfort and quality of life by helping manage symptoms such as:

Pain

Breathing difficulties

Fatigue

Loss of appetite

Nausea

Emotional distress

Supportive care can be provided alongside cancer treatment. WHO emphasizes the importance of supportive and palliative care for people with lung cancer and their families. World Health Organization

Lung Cancer Screening

Screening aims to find cancer before symptoms develop.

For people at sufficiently high risk, low dose computed tomography, commonly called LDCT, may be recommended.

Screening is not appropriate for everyone because it can also produce false positive results, unnecessary follow up procedures and other potential harms.

In the United States, the CDC describes annual LDCT screening for adults aged 50 to 80 years who have at least a 20 pack year smoking history and who currently smoke or quit within the previous 15 years, consistent with recommendations from the US Preventive Services Task Force. CDC

Screening criteria can differ between countries and health systems. Anyone considering screening should discuss their personal risk with a qualified healthcare professional.

What Is a Pack Year?

A pack year is a way of estimating a person’s lifetime cigarette exposure.

For example:

Smoking one pack of cigarettes per day for 20 years equals 20 pack years.

Smoking two packs per day for 10 years also equals 20 pack years.

This measurement helps doctors determine eligibility for certain lung cancer screening programs. CDC

Can Lung Cancer Be Prevented?

Not every case of lung cancer can be prevented, but many cases are potentially avoidable.

Do Not Smoke

The most effective prevention strategy is to avoid tobacco smoking.

For people who already smoke, quitting is beneficial at any age. Lung cancer risk decreases after quitting, although the risk does not immediately return to the level of someone who never smoked. CDC+1

Avoid Secondhand Smoke

Keep homes and vehicles smoke free.

Avoiding secondhand tobacco smoke can reduce exposure to cancer causing chemicals.

Test for Radon

If radon is a concern in your area, testing indoor air for radon can identify elevated exposure.

If levels are high, appropriate measures can reduce radon inside the building. CDC

Reduce Workplace Exposure

Workers should follow appropriate safety procedures when exposed to substances associated with lung cancer.

Proper protective equipment, ventilation and workplace controls can help reduce exposure.

Pay Attention to Air Quality

Reducing exposure to heavily polluted air when possible can contribute to healthier lungs.

Broader public health measures that reduce air pollution are also important for reducing lung cancer risk. World Health Organization

Lung Cancer and Lifestyle

A healthy lifestyle cannot guarantee protection against lung cancer, but it can support general health and may help people tolerate cancer treatment better.

Useful habits include:

Avoiding tobacco

Maintaining regular physical activity

Eating a balanced diet

Maintaining a healthy weight

Limiting exposure to environmental and occupational hazards

People receiving cancer treatment should discuss significant diet or exercise changes with their healthcare team.

Can Lung Cancer Be Cured?

Sometimes.

The possibility of cure depends heavily on the type and stage of cancer, biological characteristics of the tumor and the person’s overall health.

Some early lung cancers can be treated with the goal of eliminating the disease completely.

Advanced lung cancer may not always be curable, but modern treatments can sometimes control the disease for substantial periods and improve quality of life.

Treatment outcomes continue to change as new targeted medicines, immunotherapies and other approaches become available.

Living With Lung Cancer

A lung cancer diagnosis can affect much more than physical health.

People may experience:

Fear

Anxiety

Depression

Financial stress

Changes in family relationships

Treatment related fatigue

Changes in daily activities

Emotional and practical support is therefore an important part of cancer care.

Patients may benefit from talking with their oncology team, family members, counselors, support groups or other cancer care professionals.

Questions to Ask Your Doctor

If you or someone close to you has been diagnosed with lung cancer, useful questions include:

What type of lung cancer do I have?

What stage is it?

Has the cancer spread?

Do I need molecular or biomarker testing?

What treatment options are available?

What are the goals of treatment?

What side effects should I expect?

Would a clinical trial be appropriate?

Should I receive palliative or supportive care?

What should I do to protect my overall health during treatment?

Writing questions down before appointments can make medical discussions easier.

Important Warning Signs You Should Not Ignore

Some symptoms deserve prompt medical attention, particularly when they persist or worsen.

These include:

Coughing up blood

Persistent or worsening cough

Unexplained weight loss

Persistent chest pain

Increasing shortness of breath

Repeated chest infections

Having one of these symptoms does not mean that you have lung cancer. However, a healthcare professional should investigate persistent or concerning symptoms rather than assuming they are harmless. CDC

Frequently Asked Questions About Lung Cancer

Is lung cancer always caused by smoking?

No. Smoking is the leading risk factor, but people who have never smoked can also develop lung cancer. Radon, secondhand smoke, air pollution, occupational exposure and genetic factors can contribute to risk. World Health Organization+1

Can a nonsmoker get lung cancer?

Yes. Lung cancer can occur in people who have never smoked.

Is lung cancer contagious?

No. Cancer is not contagious. You cannot catch lung cancer from another person.

Can lung cancer be detected early?

Yes, in some high risk people through low dose CT screening. Screening is intended for people at sufficiently high risk rather than the general population. CDC

Does lung cancer always cause symptoms?

No. Early lung cancer may cause no noticeable symptoms, which is one reason it can sometimes be diagnosed at a later stage. CDC

Is coughing always a sign of lung cancer?

No. Coughing is extremely common and can result from infections, asthma, allergies, reflux and many other conditions.

However, a cough that persists or becomes worse should be evaluated.

Can quitting smoking help after a lung cancer diagnosis?

Stopping smoking is beneficial even after a cancer diagnosis. It can support overall health and may help with treatment and recovery. People who smoke should ask their healthcare team about evidence based smoking cessation support.

Lung cancer is a serious disease, but it is not a hopeless diagnosis.

Prevention, early detection in appropriate high risk individuals, accurate diagnosis, molecular testing and increasingly personalized treatments have changed the way lung cancer is managed.

The most important steps are to avoid tobacco smoke, reduce exposure to known hazards, understand personal risk, follow appropriate screening recommendations and seek medical advice when concerning symptoms appear.

If lung cancer is suspected or diagnosed, treatment decisions should always be made with a qualified healthcare team. Every person’s cancer is different, and treatment that is appropriate for one patient may not be appropriate for another.

Early medical evaluation can make a meaningful difference.

Sources and Further Reading

World Health Organization: Current global information about lung cancer, its causes, symptoms, prevention, diagnosis and treatment. World Health Organization

National Cancer Institute: Evidence based information about lung cancer types, treatment, prevention, screening and clinical research. Cancer.gov+1

Centers for Disease Control and Prevention: Information about lung cancer symptoms, risk factors, prevention, screening and statistics. CDC+2

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