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Dyspnea Supportive Care for Cancer Patients
Ernest H. Rosenbaum, MD

Dyspnea, or shortness of breath on exertion, can be a very uncomfortable sign of breathing difficulties and is not only a significant barrier to normal activities but also diminishes quality of life.

Dyspnea can come on gradually or very rapidly if a cancer progresses and blocks or compromises the respiratory system. It can be so extreme that even putting on one's shoes, dressing oneself, and walking slowly or up stairs can be highly compromised. Many patients are even short of breath while resting and require oxygen support. It has been estimated that at least 25% of terminal cancer patients have signs of dyspnea either at rest or on exertion.

This subject was reviewed by Dr. Dudgeon, in The Journal of Pain Symptom Management, 1998: 16:202-219. She notes that it is a problem with several dimensions, both physical and psychological. This is affected by the patient's previous experience, exercise tolerance, and physical being. This is seen most commonly in some 60-70% of lung cancer patients, and this figure rises to 90% in the terminal phase of lung cancer.

Breathing is under the control of the medulla and pons in the brain stem, and controls are regulated by the blood ph, CO2, oxygen level, brain control, as well as that of the respiratory muscles. Added to this are the effects it has on the chest wall with the breathing mechanism and the diaphragm for voluntary and involuntary motor control.

Thus, there are many factors that contribute to breathlessness, both neurological from the brain, the blood ph, and oxygen and CO2 levels, as well as the function of the chest wall and diaphragm. 

In breast cancer patients with metastases to the chest wall, there is often lack of function, where they cannot take a normal breath either because of pain or stiffness of the chest wall due to the metastatic cancer.

Physiology of Dyspnea
There are two major mechanisms involved. One is impaired mechanical response, where there is chest wall or muscle weakness or trouble with the diaphragm and problems with gas exchange and lung efficiencies in regulating oxygen and carbon dioxide exchange. 

Sometimes, this is caused by therapy, such as with radiation therapy, which can possibly give one radiation pneumonitis after four to eight weeks and is sometimes amenable to steroids. Also, prior lung damage from smoking can be a major factor with chronic obstructive airway problems. Often, either one or both of these mechanisms are involved with shortness of breath, dyspnea on exertion, or dyspnea at rest.

Often, primary or metastatic tumors can relate to dyspnea, such as obstruction of the main or tributary bronchi or lung compromise from progressive growth of tumor as seen in advanced lung cancer. This is often seen with a restrictive component, and this has been measured with maximum inspiratory pressure (MIP), which, in part, can be due to respiratory muscle compromise as seen in the study by Dr. Dudgeon. She found that 30% of MIPs were below normal. She also found there was no difference in patients with shortness of breath whether they had chemotherapy or radiation therapy. 

The first goal is to try to reverse the cancer process, which may help alleviate some of the dyspnea problems.  Chemotherapy and radiotherapy are used as treatments but also may cause fatigue, weakness, and dyspnea. If there are pleural effusions or pericardial effusions, they may be alleviated with thoracentesis or pericardial centesis (withdrawing fluid from the chest cavity or the pericardial sac around the heart). In addition, those who have chronic obstructive pulmonary disease (COPD) due to smoking or other causes of lung damage may have major problems with shortness of breath and dyspnea. Also, those who have lost muscle mass and have physical signs of advanced cancer, such as cachexia, may have problems with dyspnea. Oxygen can be used, and sometimes patients use fans to help direct air over their faces.

Opioid therapy may play a small role, and antianxiety drugs and Chlorpromazine may also be of benefit with or without Morphine. Nebulizers are often used and may be of some help, as well as anxiolytic agents to help relieve anxiety, which is often a side effect of shortness of breath. Steroids have played some role, especially with lymphangetic cancer, superior vena cava syndrome, pneumonitis from chemotherapy or radiotherapy, and COPD obstructive lung disease.

Abstracted by Ernest Rosenbaum, MD - Dyspnea in Cancer Patients Needs More Attention, Journal of Supportive Oncology, vol. 4, #2, February 2006, pg. 63/64.