Atelectasis and Lung Cancer: What's the Connection?

Atelectasis (also called a collapsed lung) is a potentially serious condition where the lungs do not fully expand due to a blockage or another cause, like chronic airway disease or an infection. However, it can also indicate a more serious underlying condition.

"It can be a presenting sign of lung cancer involving a central airway in the lung that is causing airway obstruction," said George Chaux, MD, board-certified interventional pulmonologist and medical director of Interventional Pulmonary at Providence Saint John’s Health Center in Santa Monica, California.

Atelectasis occurs when the tiny air sacs in the lungs, known as alveoli, collapse or are unable to inflate.

The windpipe or trachea branches into smaller tubes called bronchi, which then further divide into even smaller tubes known as bronchioles. At the end of these branching airways are alveoli, which are crucial for gas exchange in the lungs.

When anything disrupts this process and prevents the alveoli from filling with air, atelectasis can occur. The condition can affect a small portion of the lung, known as segmental atelectasis, or it can involve an entire lobe of the lung, called lobar atelectasis. In some cases, the entire lung may collapse.

There are different types of atelectasis based on the cause of the collapse.

Obstructive

Obstructive atelectasis occurs when something blocks the airways and prevents air from entering the alveoli. Some common causes of obstructive atelectasis include:

• Mucus of blood clots in the airways

• Foreign objects blocking the airways

• Tumors or growths in the lungs or nearby structures

Children are at higher risk for this type of atelectasis due to their smaller and less developed airways.

Nonobstructive

Nonobstructive atelectasis occurs when there is no airway blockage, but something prevents the alveoli from filling with air. Any of the following can cause this:

• Lung injury or trauma

• Pleural effusion (fluid in the space between the lungs and the chest wall)

• Lung fibrosis (scarring)

• Surgery on the chest or abdomen

• Respiratory conditions like chronic obstructive pulmonary disease (COPD) or asthma

• Lung cancer

"The primary difference between obstructive and non-obstructive atelectasis is the underlying cause of lung collapse," said Amina Pervaiz, MD, a board-certified pulmonologist at Karmanos Cancer Institute at Wayne State University. "The inability to expand the lung due to external pressure outside the lung or loss of lung volume leads to atelectasis without airway blockage."

Rounded

Rounded atelectasis, also known as folded lung or Blesovsky syndrome, is a rare type of atelectasis where a portion of the lung collapses and takes on a rounded shape. This can happen as a result of scarring from previous lung infections or exposure to certain substances like asbestos.

In some cases, it may be associated with underlying lung cancer. It can also mimic lung nodules or masses on imaging, making it difficult to differentiate between rounded atelectasis and a tumor.

Atelectasis as the result of restricted airflow is common in those with non-small cell lung cancer (NSCLC), according to research published in Medical Physics. As the tumor grows, it can compress or block airways, leading to lung collapse. This can also cause symptoms such as shortness of breath or a cough.

Atelectasis may happen as a complication during or after radiation therapy for lung cancer. This is known as radiation-induced lung injury and can cause scarring and inflammation in the lungs, leading to atelectasis. Research suggests that radiation treatment damages the lung cells and impairs their ability to expand.

Furthermore, other factors that increase the risk of lung cancer, such as smoking and exposure to environmental toxins, can also contribute to atelectasis by causing inflammation and lung damage.

Some people don't experience symptoms, especially if only a small segment of the lung collapses. However, a more extensive collapse can cause:

• Shortness of breath or difficulty breathing

• Rapid, shallow breathing

• Cough, which may be dry or productive

• Chest pain, particularly when taking deep breaths

• Increased heart rate

• A bluish tint to the skin and lips due to low oxygen levels

• Feeling unusually tired

Lung cancer isn't the only cause of atelectasis. Some other conditions that may also contribute to lung collapse include:

• Respiratory infections like pneumonia or bronchiolitis

• Severe asthma attack

• Inhaled foreign objects, such as food or small toys, in children

• Structural abnormalities in the lungs, such as bronchopulmonary dysplasia or cystic fibrosis

• Chronic respiratory diseases like COPD or bronchiectasis

• Lung injury, including rib fractures or lung contusions

• Smoking or exposure to secondhand smoke

Atelectasis can lead to further complications:

• Pneumonia or respiratory infection due to the collapse of the airways and ineffective clearance of mucus

• Increased risk of developing blood clots in the collapsed area

• Respiratory failure if a large portion of the lung is affected or if there are underlying respiratory conditions

• Prolonged hospital stays and delayed recovery from surgery or other procedures due to decreased lung function

"Atelectasis is usually diagnosed through imaging studies such as a chest X-ray or CT scan, which show areas of lung collapse or reduced lung volume," said Wael Harb, MD, a board-certified hematologist and medical oncologist at MemorialCare Cancer Institute at Orange Coast and Saddleback Medical Centers in Orange County, California.

Your doctor may order one or more of the following tests to help diagnose your condition:

• Arterial blood gas test to measure oxygen and carbon dioxide levels in your blood

• Pulmonary function tests to measure lung function and capacity

• Imaging, such as a chest X-ray, CT scan, or MRI

• Electrocardiogram (ECG) to check your heart function

"Clinical symptoms and physical examination findings, such as decreased breath sounds, also play a role in diagnosis," said Dr. Harb. Imaging tests may show a "volume loss in segments or entire lobes of the lung due to emptying of air from the affected lobe or lung segment," Dr. Chaux added.

Depending on the cause and severity of atelectasis, treatment options may include:

• Watch and wait: If the collapse is small and does not cause symptoms, your doctor may monitor it with repeat imaging to see if it will go away on its own.

• Breathing exercises: Deep breathing exercises, coughing, or using a spirometer can help expand the lungs and clear mucus in obstructive atelectasis.

• Chest physiotherapy: This technique involves manually manipulating the chest to help loosen and remove mucus from the airways. Your doctor may refer you to a respiratory therapist who can teach you how to do it properly.

• Medications: Bronchodilators or inhaled steroids may be prescribed to help open up airways and improve lung function.

• Oxygen therapy: If you have low oxygen levels, your doctor may prescribe supplemental oxygen to help you breathe easier and improve symptoms.

• Drainage: A chest tube may sometimes be placed to remove excess air or fluid from the lungs. This helps the lungs re-expand.

• Thoracentesis: This procedure involves inserting a needle into the chest to remove any excess fluid or air contributing to lung collapse.

• Surgery: In rare cases, surgery may be necessary to remove a tumor or repair structural abnormalities in the lungs that are causing atelectasis. This is typically only done for severe or recurrent cases.

If atelectasis occurs as a result of a tumor, your doctor may recommend surgery to remove the tumor, chemotherapy, radiation therapy, or another treatment to shrink the tumor and relieve airway obstructions, said Dr. Harb. Treatment depends on the type and stage of your cancer and tumor size.

While not all cases of atelectasis can be prevented, the following steps may help reduce your risk:

• Quit smoking and avoid exposure to secondhand smoke

• Practice deep breathing exercises after surgery or during prolonged bed rest to help keep the lungs expanded

• Move and change positions frequently, especially during long periods of sitting or lying down, to prevent mucus buildup and lung collapse

• Maintain a healthy diet and stay hydrated

Atelectasis may result from the lung cancer itself or its treatments. It can also occur as a complication of non-cancer-related respiratory conditions or environmental factors. If you experience symptoms of atelectasis, such as shortness of breath, coughing, or chest pain, it's important to tell your healthcare provider right away.

The condition can have serious complications if left untreated. Depending on the cause, your doctor may recommend observing your lung collapse, breathing exercises, medication, oxygen therapy, or surgery as treatment options.