DISEASE CHARACTERISTICS: Histologically confirmed mild, moderate, or severe bronchial dysplasia More than one suspicious area of abnormal fluorescence on bronchoscopy If only one abnormal area, lesion must be greater than 1.5 mm Current or ex-smokers who have smoked at least 30 pack years (e.g., 1 pack per day for at least 30 years) Sputum cells with morphometric index at least 7 by computer-assisted image analysis No invasive cancer on bronchoscopy or abnormal chest x-ray suspicious of lung cancer