Lung cancer occurs when cells in the lungs divide uncontrollably, causing tumors to grow. Tumors can reduce a person’s ability to breathe, and they can spread to other parts of the body.

Lung cancer is the third most common cancer type and the main cause of cancer-related deaths in the United States. According to the American Cancer Society (ACS), it is most common in males, and in the U.S., Black males are around 12% more likely to develop it than white males.

Smoking is a major risk factor, although not everyone who develops lung cancer has a history of smoking.

Lung cancer can be fatal, but effective diagnoses and treatments are improving the outlook.

This article will explain what lung cancer is, how to recognize the symptoms, and what treatment options are available.

Cancer causes changes in cells that are otherwise healthy. The cells grow too quickly, without dying off.

Healthy cells in the body usually die at a certain stage in their life cycle, thereby preventing a buildup of too many cells. In cancer, however, cells continue to grow and multiply. As a result, tumors develop.

The two main types of lung carcinoma are small-cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC), depending on how they appear under a microscope. NSCLC is more common than SCLC.

Anyone can develop lung cancer, but cigarette smoking and having exposure to smoke, inhaled chemicals, or other toxins can increase the risk.

The main types of lung cancer are NSCLC and SCLC. They differ in the size of cell, as seen under a microscope.


Around 84% of lung cancer cases in the U.S. are NSCLC.

There are three subtypes:


Around 13% of lung cancer cases in the U.S. are SCLC. This type tends to grow more quickly than NSCLC.

People with lung cancer may not have any symptoms until a later stage. If lung cancer signs do appear, they can resemble those of a respiratory infection.

Some possible symptoms include:

In time, a person may also experience more severe symptoms, such as:

Learn more about the early signs of lung cancer here.

The staging of cancer describes how far it has spread through the body and how severe it is. Staging helps healthcare professionals and individuals decide on a suitable course of treatment.

The most basic form of staging is as follows:

  • localized, wherein the cancer is within a limited area
  • regional, wherein the cancer has spread to nearby tissues or lymph nodes
  • distant, wherein the cancer has spread to other parts of the body

Similar to this is the TNM staging system. Healthcare professionals assess the tumor for size and spread, whether or not it affects the lymph nodes, and whether or not it has spread elsewhere.

There are also specific ways of staging NSCLC and SCLC.

Learn more about the stages of lung cancer here.

Stages of NSCLC

Healthcare professionals typically use tumor size and spread to describe the stages of NSCLC, as follows:

  • Occult, or hidden: The cancer does not show up on imaging scans, but cancerous cells might appear in the phlegm or mucus.
  • Stage 0: There are abnormal cells only in the top layers of cells lining the airways.
  • Stage 1: A tumor is present in the lung, but it is 4 centimeters (cm) or under and has not spread to other parts of the body.
  • Stage 2: The tumor is 7 cm or under and might have spread to nearby tissues and lymph nodes.
  • Stage 3: The cancer has spread to lymph nodes and reached other parts of the lung and surrounding area.
  • Stage 4: The cancer has spread to distant body parts, such as the bones or brain.

Stages of SCLC

SCLC has its own categories. The stages are known as limited and extensive, and they refer to whether the cancer has spread within or outside the lungs.

In the limited stage, the cancer affects only one side of the chest, although it might already be present in some surrounding lymph nodes.

The ACS states that around one-third of people with this type of the condition find out they have cancer when it is in the limited stage. Healthcare professionals can treat it with radiation therapy as a single area.

In the extensive stage, the cancer has spread beyond the one side of the chest. It may affect the other lung or other parts of the body.

The ACS notes that around two-thirds of people with SCLC learn they have it when it is already in the extensive stage.

Below, we outline the chances of surviving for 5 years or longer after receiving a diagnosis of lung cancer, as estimated by the ACS.

The percentages reflect the chances of a person surviving with lung cancer compared with the chances of a person surviving without the condition.


StageSurvival rate


StageSurvival rate

As lung cancer progresses, it can cause several complications. This may be due to side effects associated with certain cancer treatments or the spread of cancer to other parts of the body.

Some possible complications of lung cancer include:

  • Superior vena cava syndrome: Tumors around the upper area of the right lung can obstruct blood flow through the superior vena cava, a large vein that carries blood from the upper body to the heart. This may lead to superior vena cava syndrome, a condition causing facial swelling, dizziness, and loss of consciousness.
  • Metastasis: Lung cancer may spread to other parts of the body, including the brain, bones, and adrenal glands. This is more common with advanced stages of lung cancer.
  • Lung infections: People with lung cancer have a higher risk of lung infections, such as pneumonia or bronchitis, due to decreased immune function, which may be a result of the cancer itself or certain cancer treatments, such as chemotherapy.
  • Heart blockage: Although rare, lung cancer can spread to the heart and may compress or obstruct the veins and arteries. This can cause issues such as fluid buildup, heart blockage, arrhythmias, or heart attack.
  • Hypercalcemia: Lung cancer can elevate calcium levels in the blood, which health experts call hypercalcemia. This may lead to nausea, vomiting, excessive thirst, and stomach pain. According to estimates, hypercalcemia affects up to 30% of individuals with all types of cancer.
  • Blood clots: People with lung cancer have an increased risk of deep vein thrombosis, which occurs when a blood clot forms in a deep vein. If this blood clot travels to the lungs, it can prevent blood flow and could cause a pulmonary embolism, which may be fatal.
  • Neuropathy: Pancoast tumors, which are a type of tumor located at the top of the lungs, can affect the nerves in the eyes, face, and shoulders. This can cause arm and shoulder pain and Horner’s syndrome, which is a condition that can result in droopy eyelids and changes in pupil size.
  • Spinal cord compression: Cancer can spread from the lungs to the spine, which can compress the vertebrae, causing back pain, weakness, and difficulty walking. According to one study, this condition may affect around 28% of individuals with lung cancer.

Undergoing regular screening may be a good idea for people with a high risk of developing lung cancer. Screening is with a low dose CT scan.

The American Lung Association(ALA) recommends screening if a person meets all of the following criteria:

  • They are aged 55–80 years.
  • They have a history of heavy smoking, meaning 30 pack years, which is one pack per day for 30 years or two packs per day for 15 years.
  • They currently smoke or have quit smoking within the past 15 years.

Insurance will often cover this screening if a person is aged 55–80 years and has private health insurance or is aged 55–77 years, has Medicare, and meets all the other criteria.

However, people should check with their insurance company before signing up for lung cancer screening.

Additionally, false positive results sometimes occur when screening for lung cancer. The ALA estimates that around 12–14% of initial screening scans for lung cancer will have a false positive.

However, advances in screening methods have helped reduce the rate of false positives over time. Also, if a person undergoes regular screening, it allows physicians to detect changes more easily between scans to prevent false positives.

A person should speak with a doctor about the likelihood of false positives and what to expect after screening.

If a person has any symptoms that could indicate lung cancer or if screening shows something unusual, a healthcare professional will likely recommend some diagnostic tests.

Imaging tests

An X-ray, a CT, an MRI, or a PET scan might reveal areas of lung tissue with cancer.

If the cancer has spread, imaging tests can also reveal changes to bones and other organs. Moreover, scans can help track the progress of treatment.

Tissue sampling

A healthcare professional may wish to take a biopsy to check for cancer cells. They will do this using a fine needle or a bronchoscope.

A bronchoscope is a thin, lighted scope with a camera on the end that enters the lungs through the mouth or nose. A healthcare professional can use it to look for lesions and take samples.

For less accessible lesions, they may use a more invasive surgical procedure, such as thoracoscopy or video-assisted thoracic surgery, to remove lung tissue.

Other samples

Laboratory tests can also reveal whether or not cancer is present in the:

This information can help confirm whether cancer is present and, if it is, determine its type and stage.

Treatment will depend on various factors, including:

  • the type of cancer
  • the location and stage
  • the person’s overall health
  • their individual preferences

All the treatment options can have adverse effects. A person should consult a healthcare professional about the most suitable choice for them, including the pros and cons of each option.

Some treatment options include:

  • surgery to remove part or all of a lung
  • chemotherapy, which refers to a drug treatment that can kill cancer cells and shrink tumors
  • radiation therapy, which uses high energy rays to kill cancerous cells
  • radiofrequency ablation, wherein a healthcare professional inserts a thin needle and uses an electric current to destroy cancer cells
  • targeted therapy, which targets a specific behavior to prevent tumor growth
  • immunotherapy, which helps the body fight cancer cells
  • palliative therapy, including pain relief, oxygen therapy, and other help that a person may need to manage their symptoms

A healthcare professional will work with the individual and adjust their treatment plan as their needs change.

Smoking tobacco is the most common cause of lung cancer. According to estimates, about 80% of lung cancer deaths stem from smoking.

However, not everyone who has lung cancer smokes, and lung cancer can occur due to several other factors, including:

Although it is not possible to prevent all lung cancers, there are several steps a person can take to reduce their risk of the condition. These include the following:

  • Quit smoking, if applicable: According to the ACS, quitting smoking can lower the risk of lung cancer, regardless of a person’s age or how long they have smoked.
  • Avoid secondhand smoke: Breathing in smoke can cause numerous health issues and may increase the risk of lung cancer.
  • Follow a balanced diet: Eating a variety of nutrient-dense fruits and vegetables may help protect against lung cancer.
  • Avoid exposure to radon: Radon is a colorless, odorless gas that can cause lung cancer. Testing kits are available to measure radon levels at home. Additionally, individuals who work in areas with a higher risk of radon exposure should follow all recommended safety procedures to minimize health hazards.

Lung cancer can be fatal, but emerging treatments mean that many people now survive and recover from lung cancer, especially if they receive an early diagnosis.

Some factors affecting the likelihood of a positive outcome include:

  • a person’s overall health
  • their age
  • the stage of cancer at diagnosis
  • the type of cancer they have

It is not possible to predict exactly how cancer will affect an individual, but a healthcare professional can help a person understand what they may be able to expect by looking at the results of tests and other factors.

Lung cancer is a potentially fatal type of cancer, but people who receive an early diagnosis often have a good chance of survival.

Individuals with a high risk of developing lung cancer may wish to consider undergoing regular screening. This can help detect the early signs and allow for treatment before the cancer spreads.

Anyone who has concerns about their risk of lung cancer should seek guidance from a healthcare professional.