Lung Damage Following Blood Cancer Treatment

What Cancer Treatments Can Harm the Lungs and How is it Treated?

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What is meant by lung damage (pulmonary toxicity) from cancer treatment, how would I know if I had it, and how is it treated?

Cancer Treatment Induced Pulmonary Toxicity (Lung Damage)

One of the lesser-known side effects of treatment for blood and marrow cancers is lung damage. This type of lung damage may also be called pulmonary toxicity or lung toxicity. Pulmonary toxicity can range from inflammation of the lining of the lungs to permanent scarring of the lung tissues.

It has been estimated that as many as 10% of patients who receive chemotherapy - at least the types of chemotherapy used for blood cancers - will have pulmonary side effects.

What Causes Pulmonary Toxicity?

Pulmonary toxicity is a potential side effect of both chemotherapy and radiotherapy. What causes pulmonary toxicity is not clearly understood. However, scientists have discovered a number of factors that they feel play a role in how pulmonary toxicity develops.

  • Interaction between chemotherapy and radiotherapy with oxygen molecules
  • A direct toxic effect on the DNA of lung cells
  • Inflammatory response of the lung tissues following exposure to chemotherapy or radiation

Symptoms of Pulmonary Toxicity

Symptoms of treatment related pulmonary toxicity are fairly non-specific and can easily be confused with other lung conditions. Common signs of treatment related lung damage include:

  • Dry cough
  • Shortness of breath
  • Chest pain
  • Rapid breathing
  • Difficulty catching your breath
  • Fever

In some cases, signs of pulmonary toxicity may become evident during treatment, or it may take several months for symptoms to begin.  On average, symptoms related to lung damage begin 6 to 8 weeks after the onset of treatment.

Because these symptoms are similar to other conditions that can be experienced by cancer patients such as pneumonia or the spread of malignant cells into the lungs, specialists must rule these out before assuming a diagnosis of treatment related pulmonary toxicity.

  In other words, lung toxicity is a "diagnosis of exclusion."

What Treatments are Most Likely to Cause Pulmonary Toxicity?

Many types of chemotherapy drugs have been linked to pulmonary toxicity. Some of the most common that are used in the treatment of blood and marrow cancers are:

  • Bleomycin
  • Idarubicin
  • Methotrexate
  • Cyclophosphamide
  • Busulfan
  • Arsenic trioxide

Radiation therapy to the chest area may also cause pulmonary toxicity. This effect may be more pronounced if you have received radiotherapy in combination with chemo.

Risk factors For Developing Pulmonary Toxicity

The factors that place certain patients at higher risk of developing pulmonary toxicity are unclear and often debated. However, the following have been proposed as risk factors:

  • Use of oxygen therapy during chemotherapy cycles

Diagnosing Treatment Related Pulmonary Toxicity

Identifying patients with pulmonary toxicity can be very difficult on account of the non-specific signs and symptoms and the lack of definitive testing options. For the most part, specialists arrive at a diagnosis of treatment related pulmonary toxicity after all other causes, such as pneumonia, have been excluded.

Clinicians will typically use blood tests such as a complete blood count with differential, chest X-rays or CT scans, pulmonary function testing (PFT) and sometimes bronchoscopy to rule out infection or spread of cancer cells in the lungs as a cause of symptoms. If no other reason can be identified, and you have had a high risk therapy recently, your specialist may determine that your lung problems have been caused by your cancer treatment.

Treatment of Pulmonary Toxicity

If your doctor strongly suspects that your lung damage is related to one of the treatments or medications you are receiving, they will most likely stop that agent. In some cases, they may replace the medication with another less toxic one or just eliminate the drug altogether. While it can be distressing to have a change in your therapy, your doctor would not take this decision lightly.

There is no specific treatment for lung damage caused by cancer therapies, there are a few things that might help with the symptoms you might experience:

  • Steroids to decrease the inflammation in your lungs
  • Cautious use of oxygen therapy
  • Narcotics to help relieve discomfort and help relieve the shortness of breath
  • Relaxation exercises
  • Respiratory physiotherapy (pulmonary rehabilitation)
  • Quitting smoking
  • Physical activity and exercise

Life After Pulmonary Toxicity

Serious cases of pulmonary toxicity can be fatal. In some cases, the lung damage caused by cancer treatment may be permanent. However, in many circumstances, when patients survive these adverse lung reactions, they recover completely with no residual effects remaining.

Summing it Up

Lung damage can result from either chemotherapy or radiotherapy in the treatment of cancer. As our therapies for blood and marrow cancers have become more effective, people are living much longer than ever before after treatment. Therefore, care plans need to take into account the long term impact of respiratory toxicity in addition to the potential to cure these conditions.

Sources

Maldonado, F., Limper, A., and J. Jett. Pulmonary toxicity associated with antineoplastic therapy: Cytotoxic agents. UpToDate. Updated 09/28/15. http://www.uptodate.com/contents/pulmonary-toxicity-associated-with-antineoplastic-therapy-cytotoxic-agents

Pal, S. Bleomycin Induced Lung Injury. UpToDate. Updated 09/14/15. http://www.uptodate.com/contents/bleomycin-induced-lung-injury

Shippee, B., Bates, J., and K. Richards. The role of screening and monitoring for bleomycin pulmonary toxicity. Journal of Oncology Pharmacy Practice. 2015 Mar 2. (Epub ahead of print).

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