Cardiopulmonary Syndromes (PDQ®): Supportive care - Health Professional Information [NCI] - Dyspnea and Coughing in Patients With Advanced Cancer
Dyspnea is defined as an uncomfortable awareness of breathing. It is a subjective experience involving many factors that modulate the quality and intensity of its perception. Patients with comparable degrees of functional lung impairment and disease burden may describe varying intensities of dyspnea. Patients use a host of different words and phrases to describe the sensation of breathlessness. Terms such as tightness and suffocating are sometimes used.
Metastases at diagnosis are detected in approximately 25% of patients. The prognosis of patients with metastatic disease is poor. Current therapies for patients who present with metastatic disease achieve 6-year event-free survival (EFS) of approximately 28% and overall survival (OS) of approximately 30%.[2,3] For patients with lung/pleural metastases only, 6-year EFS is approximately 40% when utilizing bilateral lung irradiation.[2,4] In contrast, patients with bone/bone marrow metastases have...
Reports on the frequency of dyspnea also vary, depending on the setting and the extent of disease. In one study, 49% of a general cancer population reported breathlessness, and 20% rated their breathlessness as moderate to severe. Patients with advanced cancer experience this symptom more frequently and more intensely than do patients with limited disease. One study found that 75 of 135 patients with advanced cancer reporting to an outpatient palliative care clinic were experiencing moderate-to-severe dyspnea. Breathlessness was a complaint at presentation in 60% of 289 patients with lung cancer. Results of a large study showed that 70% of patients suffered from dyspnea in the last 6 weeks of life. About one third of patients who could report the intensity of their dyspnea rated it as moderate to severe. Another study revealed that half of patients with advanced cancer scored their dyspnea as moderate to severe.
The pathophysiological mechanisms of breathlessness are numerous and complex. Peripheral and central mechanisms as well as mechanical and chemical pathways are involved.
The direct causes of dyspnea in patients with advanced cancer are numerous; categorizing them can assist in the etiologic work-up. One approach is to divide direct causes into the following four groups:
Direct tumor effects such as intrinsic or extrinsic airway obstruction, pleural involvement, parenchymal involvement either by primary or metastatic disease, superior vena cava syndrome, lymphangitic carcinomatosis, and pericardial effusion.
Indirect tumor effects such as pneumonia, a pulmonary embolus, paralysis of a hemidiaphragm, or weakening of the respiratory muscles from sarcopenia.
One study found that in patients experiencing dyspnea from advanced cancer, a median of five different abnormalities could have contributed to their shortness of breath. Spirometry was abnormal in 93% of 100 patients examined, with 5% having obstructive patterns, 41% restrictive patterns, and 47% mixed patterns; 49% of patients had lung cancer, 91% had abnormal chest radiographs, and 65% had parenchymal or pleural involvement. These results indicate that a subset of patients will experience shortness of breath without any apparent lung involvement. The potentially correctable causes of dyspnea included hypoxia (40%), anemia (20%), and bronchospasm (52%). No significant association between the type of respiratory impairment and the degree of dyspnea was found. Most of these patients were current or former smokers. Most patients also had a significant lowering of their maximum inspiratory pressures, suggesting severe respiratory muscle dysfunction. This finding was duplicated in another study. Of patients admitted to hospice care, 34% had histories of cardiac disease and 24% had histories of respiratory disease. Only 39% of terminally ill patients who reported dyspnea had lung or pleural involvement. The etiology of dyspnea could not be clearly identified in approximately one quarter of patients. Another study found that 49% of lung cancer patients presented with airflow obstruction.[7,9]