Atelectasis (pronounced at-uh-LEK-tuh-sis) is a term for the partial or complete collapse of the small airways in the lungs. Atelectasis can be due to tumors growing in lung tissue or an airway.

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Cancer develops when cells in a person’s body begin to divide uncontrollably. These abnormal cells can form tumors and cause damage to surrounding tissue, such as the lungs.

Atelectasis may occur due to tumors growing inside a person’s lungs.

Read on to learn about atelectasis and lung cancer, including its types, symptoms, causes, risk factors, complications, diagnosis, treatments, preventions, and outlook. We also answer some common questions.

A person’s windpipe splits into two bronchi, one for each lung. The bronchi then divide into smaller bronchi, which split into bronchioles. These lead to tiny air sacs known as alveoli.

Alveoli absorb oxygen from the air a person inhales and pass it into the bloodstream. They also remove carbon dioxide from the blood, which a person exhales when they breathe out.

When a person has atelectasis, their alveoli have partially or completely collapsed. This may affect a small or large area of the lung.

Research from 2018 notes that atelectasis may be the first sign of lung cancer. Researchers also state that atelectasis is present in 30–⁠35% of people with undiagnosed lung cancer.


There are several types of atelectasis:


Obstructive atelectasis occurs due to a blockage in a person’s airways. This may be a result of the following:

  • foreign bodies, such as a toy or piece of food
  • tumors
  • mucus plugs


There are various subtypes of nonobstructive atelectasis:

  • Compression: This occurs when there is increased pressure on the lungs
  • Adhesive: This results from an issue with a pulmonary surfactant, a substance that helps the alveoli stay open.
  • Cicatrization: This is due to scarring, which leads to the lung shrinking.
  • Relaxation: This results from a loss of contact between the membranes connecting to the chest wall and those covering the lungs.
  • Replacement: This occurs when tumors replace all the alveoli in a lobe.


Rounded atelectasis occurs when atelectatic lung tissue folds into the membranes covering the lungs.


Postoperative atelectasis generally occurs within 3 days of a person having a general anesthetic.

Atelectasis generally does not cause any symptoms. However, when it does cause symptoms, they can include:

  • decreased or no breath sounds
  • crackles when breathing
  • cough
  • sputum production
  • shortness of breath
  • rapid breathing
  • reduced chest expansion

Research notes that the following may cause a person to develop atelectasis:

  • lung diseases
  • being on a breathing machine
  • surgery on the chest or abdomen
  • blockages in the airway

Tumors that form in a person’s lungs may block or compress their airways, causing atelectasis.

A form of lung cancer — adenocarcinoma — develops in the alveoli. This cancer causes replacement atelectasis, one of the most severe forms. It can cause a person’s entire lung to collapse.

Certain risk factors can increase a person’s chances of developing atelectasis, including:

A study from 2022 found that atelectasis is one of the most common complications that occur at the beginning of a surgical procedure.

It can also increase the risk of death, as well as the development of conditions such as pneumonia and acute respiratory failure if a person does not receive treatment.

Doctors generally look for atelectasis in people who have risk factors. A doctor can use imaging tests to confirm the diagnosis, such as:

Additionally, a doctor can use a fiberoptic bronchoscopy to check a person’s airways. This procedure involves a doctor inserting a thin, bendable tube with a camera and a light on it into a person’s mouth to inspect their airways.

Another test a doctor can use to diagnose atelectasis is an arterial . This test measures the amount of oxygen and carbon dioxide in a person’s blood.

If a person has atelectasis due to lung cancer, a doctor may treat it in the following ways:

  • surgery to remove tumors or damaged lung tissue
  • chemotherapy
  • radiation therapy

Other treatments can include inhaled medications and assistive breathing machines.

A person may help to prevent atelectasis and lung cancer in the following ways:

  • stopping smoking if applicable
  • maintaining a moderate body weight
  • avoiding exposure to cancer-causing elements, such as radon
  • eating a balanced diet
  • managing pain adequately

The outlook for a person with atelectasis can vary depending on the condition’s cause. Atelectasis resulting from general anesthetic generally resolves itself within a day after surgery.

The American Cancer Society notes that the 5-year survival rate for a person with localized lung cancer is 64%.

Below are some common questions relating to this topic.

What are the early warning signs of lung cancer?

Lung cancer generally does not cause symptoms until it spreads. However, if it does cause symptoms, the most common include:

Can doctors mistake cancer for atelectasis?

There is no information to suggest that doctors can mistake lung cancer for atelectasis. However, there are cases of doctors mistaking rounded atelectasis for malignant growth.

What lung disease causes atelectasis?

Atelectasis can result from diseases such as:

  • pneumonia
  • tuberculosis
  • fibrosis
  • chronic destructive lung processes

Is atelectasis the same as pneumothorax?

No, atelectasis and pneumothorax are separate conditions. Pneumothorax is when the lung collapses due to air escaping into the cavity between the lung and the chest wall.

Atelectasis is a condition that causes the alveoli to partially or fully collapse. It can occur due to tumor growth resulting from lung cancer.

If a person has any signs of atelectasis or lung cancer, they should speak with their doctor.