Lung damage is a side effect of some cancer treatments. This damage may include inflammation, which reduces the amount of oxygen you can absorb, and/or scarring, which reduces the amount of air you can breathe. Both of these result in uncomfortable symptoms, including shortness of breath and fatigue. Treatment for lung damage is primarily aimed at relieving symptoms.
What are lung toxicities?
Damage to the lungs is called pulmonary toxicity, or lung toxicity. Lung toxicity may be short-term or permanent. Damage to the lungs that resolves (returns to normal after time or after the cause has been removed) is called acute lung toxicity. Damage that is long-lasting or permanent is called chronic or late pulmonary toxicity.
Lung damage often presents as inflammation, also called pneumonitis. This inflammation generally affects the cells that line the alveoli, which are small sacs in the lungs that are responsible for exchanging oxygen from the air with carbon dioxide in the blood. Inflammation of these sensitive structures makes gas (oxygen and carbon dioxide) exchange less efficient, reducing the amount of oxygen that is absorbed from the air and delivered to the body.
Another kind of damage to the lungs is fibrosis. Pulmonary fibrosis is the development of fibrous, or stiff, scar tissue in the lungs. Lung tissue is normally very elastic and it expands as you breathe in order to provide a larger space for air. Scarring reduces the elasticity of the lungs, and reduces the amount of air you can breathe in. Fibrosis can occur several months after pneumonitis has healed or it can occur without any inflammation. Fibrosis may be progressive, meaning it gets worse with time, and may become a long-term complication.
What causes lung toxicity?
Chemotherapy and radiation therapy may both cause lung toxicity. One of the ways that radiation and chemotherapy drugs damage cells is by forming free radicals. Free radicals are unstable molecules which are formed during many normal cellular processes that involve oxygen, such as burning fuel for energy. They are also formed from exposure to elements in the environment, like tobacco smoke, radiation and chemotherapy drugs. The free radical damage from radiation and chemotherapy is worse in the lungs because of the high concentration of oxygen.
Any chemotherapy drug can damage the lungs. Radiation to the chest cavity commonly causes lung toxicity. Cancers that may be treated with radiation to the chest cavity include breast cancer, lung cancer, and Hodgkin’s lymphoma. Symptoms may not occur until 2-3 months after radiation treatment.
The chemotherapy drugs that have been reported to cause lung damage include:
Notify your doctor immediately if you have any of these symptoms.
Corticosteroids: Steroids work by decreasing inflammation and relieve the cough and some pain associated with lung toxicity.
Oxygen therapy: Your doctor may prescribe supplemental oxygen, depending on the severity of symptoms, as well as your activity level. Oxygen is usually generated by a machine and delivered through a tube that you wear around your neck or face. A small, portable canister may be used that you carry or wheel on a cart. Some patients may only require oxygen at night while they sleep. Patients who have received bleomycin (Blenoxane®) are at greater risk of developing lung damage when they are given high concentrations of oxygen, as with general anesthesia.
Narcotics: These powerful pain medications also calm the breathing center in your brain, relieving shortness of breath. An example of a narcotic is morphine.
Pulmonary (lung) rehabilitation: Some medical clinics or hospitals offer a multi-disciplinary approach to managing your lung damage. These programs may include medical prescriptions, education, emotional support, exercise, breathing retraining and nutritional counseling to help you gain control of your breathing and restore your highest possible function.
1Simpson AB, Paul J, Graham J, Fatal bleomycin pulmonary toxicity in the west of Scotland1991-95: a review of patients with germ cell tumours. Br J Cancer. 1998;78:1061-6.