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by C.H. Weaver M.D. 2/2022

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.

CancerConnect Community490 General

What are lung toxicities and side effects from treatment?

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, immunotherapy, and radiation therapy may all 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.

Cancer medications more commonly associated with lung damage include:

  • Arsenic trioxide (Trisenox®)
  • Bleomycin (Blenoxane®)
  • Idarubicin (Idamycin®)
  • Enhertu
  • Carmustine 

Interstitial Lung Disease

Interstitial lung disease (ILD) related to Carmustine, Bleomycin, Enhertu and other medications can be fatal. In a recent study with Enhertu ILD occurred in 16% of participants, including 2.7% whose deaths were attributed to ILD.2


Lung inflammation or Pneumonitis Findings from a study of 205 patients with NSCLC treated with checkpoint inhibitors at Johns Hopkins Hospital in Baltimore, Maryland, between 2007 and 2017 have been reported and suggest that checkpoint inhibitor pneumonitis is much more common than previously thought. Overall it impacted 19% of patients, compared with 5% or fewer of patients in clinical trial settings.

Cough and shortness of breath and the main symptoms of pneumonitis and patients can also experience low blood levels of oxygen and visible infiltrates on chest x-ray. Almost all of the patients with serious toxicity experienced symptoms within 200 days of beginning treatment.

The pneumonitis can respond to treatment with steroids, however some patients develop difficulty breathing and require oxygen therapy and discontinuation of checkpoint inhibitor therapy.

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What are the symptoms of lung side effects?

Symptoms that you may experience if you have damage to your lungs are:

  • Breathlessness during exercise
  • Fatigue
  • Dry cough
  • Shortness of breath
  • Discomfort or worsening symptoms when lying on your back

Notify your doctor immediately if you have any of these symptoms.

General PMF Newsletter 490

How are lung side effects managed?

While there is no specific treatment to reverse lung damage, your doctor may prescribe medications or therapies to help manage the symptoms of lung toxicity.

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.

What else can I do?

There are things you can do everyday to help manage the symptoms of lung toxicity:

  • Try relaxation techniques to control your breathing, such as meditation, yoga, or deep breathing exercises.
  • Promote oxygenation (air circulation) throughout your lungs, especially the bottom, to prevent infection and pneumonia. This can be done with breathing exercises or physical activity.
  • Use an incentive spirometer, a device that makes you breathe slowly and deeply, to maintain oxygenation.
  • Find a kind of exercise that you can tolerate and do it daily.
  • Avoid smoking and smoke-filled environments. Smoking or second-hand smoke can further damage your lungs.
  • Reduce anxiety and manage stress.


  1. Simpson 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.
  2. Saura, C., Modi, S., Krop, I., Park, B. W., Kim, S. B., Tamura, K., Andre, F., Iwata, H., Ito, Y., Tsurutani, J., Sohn, J., Lee, C., Liu, Y., Cathcart, J., Singh, J., & Yamashita, T. (2021, Septembe 16-21, 2021). Trastuzumab Deruxtecan (T-DXd) in Patients with HER2-Positive Metastatic Breast Cancer: Updated Survival Results from a Phase 2 Trial (DESTINY-Breast01). European Society for Medical Oncology Annual Meeting, Lugano, Switzerland.