Induced sputum and cytological diagnosis of lung cancer

Diagnosis of lung cancer by examination of induced sputum specimens for malignant cells may be a valuable alternative to diagnosis by bronchoscopy. Patients suspected of having lung cancer were recruited and randomly distributed into two groups, one group (n = 34) having sputum induced by use of an ultrasonic nebuliser before bronchoscopy, and the other (n = 33) undergoing ordinary expectoration before bronchoscopy. 25 patients in the induced-sputum group were diagnosed as having primary lung cancer; induced sputum was positive for malignant cells in 21 of these patients (84%), whereas bronchoscopy was positive in 23 (92%) (not significantly different). In comparison, ordinary sputum was positive in 15 of 29 patients (52%) diagnosed as having primary lung cancer, whereas bronchoscopy was positive in 28 (97%) (p less than 0.001). Induction of sputum by an ultrasonic nebuliser was an effective procedure for diagnosis of primary lung cancer.