Dyspnea (a feeling of breathlessness) is a condition experienced by 20% to 90% of people with advanced cancer . It also occurs in those with earlier stage cancers who have other conditions of the heart or lungs. For example, a person with a potentially life-threatening blood clot  or other emergency may experience dyspnea, so it is important to tell your doctor right away about sudden or worsening symptoms. Common symptoms of dyspnea include the following:
- Uncomfortable breathing?
- Shortness of breath?
- Inability to get enough air?
- A feeling of smothering, drowning, or suffocation
A person may experience dyspnea even though the actual levels of oxygen are within a normal range. It is important to understand that people do not suffocate or die from dyspnea.
To learn more about your symptoms, the doctor will review your medical history and ask you to describe your symptoms and any activities or other medical conditions that make the symptoms worse. The doctor may also ask you to rate your symptoms on a scale.
Relieving side effects, also called symptom management, palliative care , or supportive care, is an important part of cancer care and treatment. Talk with your health care team about any shortness of breath you experience, including any new symptoms or a change in symptoms.
Dyspnea may be caused by a tumor or by other conditions related to cancer, and many of these causes are treatable. Some common causes of dyspnea include the following:
- Airway obstruction (something, such as a tumor, blocking the airway)
- Anxiety ?
- Bronchospasm (a narrowing of the airway)?
- Hypoxemia (a shortage of oxygen in blood)?
- Pleural effusion  (fluid in the space between the edge of the lungs and the chest wall)?
- Radiation pneumonitis (inflammation of lungs after radiation treatment)?
- Anemia  (a low red blood cell count)?
- Stress 
Treatment of dyspnea involves treating the underlying cause, such as the tumor, or treating a condition, such as a blood clot. The doctor may also recommend the following to help to relieve the symptoms of dyspnea:
- Receiving extra oxygen; or, sitting in front of a fan, which may be just as effective as extra oxygen?
- Breathing cleaner, cooler air by lowering the temperature in a room, opening a window, using a humidifier, or getting rid of smoke and pet dander
- Getting a sense of open space by opening windows, seeing a view of the outside, or being in an empty room
- Keeping your head lifted. If you are in bed, use pillows to raise your head so that you are nearly sitting.
- Practicing distraction and relaxation techniques (such as meditation)
- Taking opioid medications (pain medications, such as morphine, that act on the central nervous system)?
- Taking anti-anxiety drugs to manage the pain and anxiety of dyspnea