The pattern of respiratory infection in patients with lung cancer.

We examined retrospectively the pattern of respiratory infection in 579 patients with lung cancer admitted to Nagasaki University Hospital during the past 15 years. A total of 139 patients (24.0%) developed respiratory infection. The rates of pulmonary infection associated with large (36.2%) and small cell carcinomas (33.6%) were significantly higher than those with squamous cell carcinoma (26.0%) and adenocarcinoma (17.3%). Advanced stages of lung cancer were associated with higher complication rates (stage I: 6.3%, stage II: 15.9%, stage III: 27.9%, and stage IV: 33.8%). Deceased patients showed a significantly higher rate of pulmonary infection than alive patients during the period of investigation. Isolated organisms in excess of 10(7) cfu/ml in sputum or 10(4) cfu/ml in bronchial aspirate were mainly gram-negative bacteria (68.8%), such as Haemophilus influenzae, Klebsiella pneumoniae, Enterobacter cloacae, Acinetobacter sp. and Pseudomonas aeruginosa. The number of patients infected with gram-positive bacteria increased markedly after 1982. Our results suggest that a successful control of pulmonary infection associated with lung cancer is important in improving the prognosis of lung malignancy.