A 54-year-old female seeks medical attention with a complaint of worsening exertional dyspnea of 3 to 4 weeks’ duration. She has a history of small-cell lung carcinoma, first diagnosed 3 months previously, and has had an excellent response to treatment, which included both chemotherapy and external-beam radiation. Consistent with her cancer diagnosis, she has a 30 pack-year history of cigarette smoking, and her pulmonary function tests indicate mild airflow obstruction, slight hyperinflation on lung volumes, and a mildly decreased diffusion capacity. In addition to her dyspnea with exertion, the patient describes symptoms of an intermittently productive cough, fatigue, and, recently, a poor appetite.
This could be a typical case encountered by an oncologist, pulmonary/critical-care physician, or primary-care physician. Variations on the theme of dyspnea and cough are two of the most common problems that the pulmonary specialist deals with on an outpatient basis, and it would not be unusual for the above patient to be referred to us or one of our colleagues at some point for further evaluation. In this issue of ONCOLOGY, Jay R. Thomas and Charles F. von Gunten provide a succinct template for the treatment of such patients.
A Complex, Integrated Process
As the authors state in their first paragraph, dyspnea is defined as a sensation of difficult or uncomfortable breathing and has been reported to occur in 21% to 90% of cancer patients. For some individuals, dyspnea is described as breathlessness, while others feel a sense of restriction in their breathing or even a vague feeling of chest discomfort. Drs. Thomas and von Gunten appropriately emphasize that this subjective sense of discomfort while breathing is the physiologic manifestation of a complex and integrated process involving input from several sourcesie, from the airway and lung parenchyma as well as the brain’s respiratory center, the cerebral cortex, peripheral musculature, and the central and peripheral chemoreceptors.
Although the subjective feeling of dyspnea is a common symptom among individuals with advanced primary lung cancer or those with metastatic spread to the lung, it is also found in individuals with no demonstrable pulmonary or pleural involvement. It is not surprising that the National Hospice Study found that 24% of oncology patients experienced dyspnea with no known cardiopulmonary process.
Etiology of Dyspnea
The authors state that it is important to initiate a reasonable evaluation of the cause of the patient’s dyspnea. As they point out, dyspnea in cancer patients is usually multifactorial, with more than one potential cause per patient. Their review suggests that, as potential causes of dyspnea, pulmonary or pleural involvement should be at the forefront of such an evaluation.