Untersuchungen zum Wert der Sputumzytologie bei Lungentumoren
Objective: More than 1,3 million people are diagnosed as having lung cancer worldwide each year. Sputum cytology in the process of diagnosing lung cancer lost its importance with the introduction of the fibre bronchoscope in 1968. The aim of this study was the evaluation of sputum cytology as diagnostic procedure for the diagnosis of lung cancer. Methods: Overall 79 patients who were suspected of having lung cancer had bronchoscopy and histological investigation of their specimens. Histological
... imens. Histological findings revealed two groups, one (n = 21) having benigne lung sickness e.g. infections the other (n = 58) having lung cancer. The cancer group included 52 patients with primary lung cancer and 6 patients with a recurrency of primary lung cancer and lung metastasis. Sputum was collected 2 times within 2 days after inhalation of 3% saline nebula. At least two slides were prepared from each sputum sample with the pick and smear method and were stained with the Giemsa stain. A specimen was accepted as satisfactory for cytological assessment if alveolar macrophages were present. Results: Cytological sputum examination showed a diagnostic sensitivity of 57% and a negative predictive value of 44%. Sputum cytology achieved a high specificity and positive predictive value of 95% and 97%. Cytotyping accuracy was 92,8%. The sensitivity increased from 42% with one specimen to 61% with the second specimen. Only one patient with a squamous cell dysplasia following from a pulmonary infection had a false-positive result. Discussion and conclusion: The method should not be used as a stand alone diagnostic tool. Sputum cytology in combination with non invasive diagnostic procedures is acceptable save to diagnose lung cancer. Sputum cytology is a valuable diagnostic tool. It is less accurate as histology but has the advantage of being less invasive. It may be indicated in patients with severe morbidity.