Introduction

Dyspnea or breathlessness is a normal sensation we all experience from time to time, but which becomes a serious and sinister symptom in patients with advancing malignancy. It has been described simply as “an uncomfortable awareness of breathing,” but that does not convey the full impact on the patient. A more comprehensive definition is “the subjective sensation of difficulty or undue effort in breathing, which is not necessarily related to exercise, and which compels the individual to either increase ventilation or to reduce activity.”

The actual words that patients use to describe the sensation may vary depending on the severity, psychological effects, and to some extent, the causes. Thus people with long-term chronic airflow limitation often speak of “tightness;” those with sudden onset of pulmonary embolism of “gasping;” a patient who has cardiac failure may feel he is “drowning.” The words used, however, are not sufficiently consistent to be useful in diagnosis.

Prevalence and impact

Dyspnea is a very common symptom in patients with cancer, and in lung cancer it may be the reason for initial presentation. A recent large screening study of a mixed cancer population found the prevalence to range from 33% in sarcoma to 83% in lung cancer patients. In general, the symptom becomes more common with advancing disease – this reflects both a real increase in the pathophysiological factors which predispose to dyspnea, and also the lack of efficacy of many current treatments.