Induced sputum in the diagnosis of peripheral lung cancer not visible endoscopically

The diagnosis of small peripheral lung cancer is difficult to achieve by no n-invasive methods. We hypothesized that in these patients induced sputum m ight increase the diagnostic yield over spontaneous sputum, representing a good diagnostic alternative in selected patients. We prospectively evaluate d 60 patients with peripheral lung lesions and normal bronchoscopic evaluat ion. Six samples of sputum (three spontaneous and three induced with nebuli zation of hypertonic saline) before bronchoscopy and six samples of sputum after bronchoscopy (three spontaneous and three induced) were obtained in e ach subject. Forty-two out of the 60 patients included were finally diagnos ed with lung cancer. Eighteen patients were diagnosed with different benign conditions of the lung. Overall, malignant cells in sputum were observed i n 21 patients and in all but one, the final diagnosis of lung cancer was ac hieved, Only one patient with a pseudoinflammatory tumour of the lung had a false-positive result in one spontaneous sputum sample. The diagnosis of l ung cancer was obtained in 18 patients with the induced sputum (43%) and in 14 patients with spontaneous sputum (31%) (P=NS). Samples of induced sputu m were more adequate for cytological analysis than samples of spontaneous s putum (P < 0.0001). Of 13 patients with peripheral lung neoplasms of 2 cm o r less in diameter, five were diagnosed using induced sputum (38%) and only one using spontaneous sputum (8%) (P < 0.05). In conclusion, induced sputu m is a valuable technique for the diagnosis of peripheral lung cancer. Indu ced sputum gives better quality specimens and better diagnostic yield in sm all lesions than the spontaneous sputum and may be indicated in selected pa tients with disseminated disease, inoperability or severe co-morbilities. ( C) 2001 Harcourt Publishers Ltd.