CYTOKINETIC ANALYSIS OF LUNG-CANCER BY INVIVO BROMODEOXYURIDINE LABELING

Cytokinetic parameters of various types of lung cancer were determined in bronchoscopy specimens after in vivo labelling with the thymidine analogue bromodeoxyuridine (BrdU). The S-phase fraction and BrdU label ling index were measured flow cytometrically, allowing calculation of the S-phase transit time and potential tumour doubling time. The metho dology used was found to be feasible for obtaining cytokinetic data fr om 76% of the bronchial biopsy samples. Despite the difference in clin ical behaviour and growth pattern between small cell lung cancer (SCLC ) and non-small cell lung cancer (NSCLC), no significant differences w ere observed between the mean values of the cytokinetic parameters of SCLC and NSCLC. The estimated cell loss factor was higher in NSCLC tha n in SCLC. It appears that the growth of a tumour, as clinically obser ved, is to a considerable extent influenced by cell loss. In accord wi th this assumption is the fact that we have observed non-BrdU labelled S-phase cells, both in tumour biopsies and in apparently normal tissu e. The presence of these so-called unlabelled S-phase cells in relatio n to cell loss is discussed.