Malignant Central Airway Obstruction

Malignant central airway obstruction (MCAO) is a narrowing or blockage of the trachea (windpipe) or the large bronchi leading into each lung, caused by cancer. The blockage can come from three sources: a tumor growing inside the airway, a tumor or enlarged lymph nodes pressing on the airway from outside, or a mix of both. Lung cancer is the most common cause. Cancers of the esophagus, thyroid, and head and neck, along with cancers that spread to the chest (such as kidney, breast, colon, and melanoma), can also block the airways.

Symptoms often come on gradually and can be mistaken for asthma, COPD, or a lingering infection. Common symptoms include:

• Shortness of breath: often gets worse over days or weeks, especially with activity or when lying down

• Wheezing or stridor: a whistling or harsh sound when breathing, sometimes heard on only one side of the chest

• Persistent cough: a cough that doesn’t improve with standard treatment

• Coughing up blood (hemoptysis): anything from streaks in the mucus to larger amounts

Some patients notice signs that aren’t as clearly linked to the airway, including:

• Repeated pneumonia in the same part of the lung, caused by mucus trapped behind the blockage

• Collapsed lung segments (atelectasis) that show up on a chest X-ray

• Trouble lying flat or a need to sleep in a certain position to breathe comfortably

• Hoarseness or trouble swallowing when nearby nerves or the esophagus are involved

Diagnosis starts with a review of your cancer history and symptoms, followed by a physical exam. A CT scan of the chest is usually the first imaging test, since it shows where the blockage is and whether it’s inside the airway, pressing on it from outside, or both. Bronchoscopy lets your pulmonologist see the airway directly, measure how narrow it has become, and take tissue samples if needed. Pulmonary function testing can also help show how much the obstruction is affecting your breathing.

Treatment depends on the type of blockage, where it is, and how severe your symptoms are. Options include:

• Tumor debulking: removing tumor tissue from inside the airway with a bronchoscope to reopen the passage

• Thermal ablation: using laser, electrocautery, or argon plasma coagulation to destroy tumor tissue and control bleeding

• Cryotherapy: freezing tumor tissue so it can be removed

• Balloon dilation: gently stretching a narrowed airway open

• Airway stenting: placing a silicone or metal stent to hold the airway open, especially when a tumor is pressing from outside

These procedures can relieve symptoms quickly, often right away. They’re usually combined with chemotherapy, immunotherapy, or radiation to treat the cancer itself.

Managing MCAO is a team effort between your pulmonologist, oncologist, and radiation oncologist. After the airway is opened, ongoing care may include:

• Follow-up bronchoscopies to check the airway and any stents

• Saline nebulizers and other airway-clearance techniques to keep mucus from building up

• Watching for any new or worsening shortness of breath, wheezing, or bleeding, and reporting it right away

• Coordinating airway care with your cancer treatment schedule

Anyone with cancer in or near the chest can develop airway obstruction, but some factors make it more likely, including:

• Lung cancer: up to about 30% of lung cancer patients develop central airway obstruction at some point

• Tumors located near the center of the chest, close to the trachea and main bronchi

• Enlarged lymph nodes in the chest from cancer spread

• Cancers of nearby organs, such as the esophagus or thyroid

• Advanced or metastatic disease, especially cancers known to spread to the airways

If you have severe shortness of breath, trouble breathing at rest, loud stridor, a bluish tint to your lips, or you’re coughing up more than a small amount of blood, call 911 or go to the nearest emergency room. MCAO can sometimes get worse quickly, and early treatment usually leads to better outcomes.