The relationship between growth rate, labelling index and histological type of human solid tumours

Abstract

Data on the labelling index of human solid tumours have been collected from the literature and pooled with the authors' own results. Mean values for five histological groups have been calculated. For the embryonal tumours and the hematosarcomas, the mean value of the labelling index ( L.I. ) is of about 30 per cent and appears to correspond to a growth fraction (G.F.) close to 100% The L.I. for the 3 other groups (squamous cell carcinomas, mesenchymal sarcomas and adenocarcinomas) are significantly lower, the lowest being for adenocarcinomas for which the L.I. is of about 2%. The L.I. of these five groups have been compared with the previously evaluated growth rate. The L.I. and the doubling time (D.T.) of these five groups are negatively correlated and G.F. appears to be the main parameter of the kinetics of tumour cell proliferation to explain the differences in the growth rates of human cancers. Cell-loss factors were estimated for the five groups of tumours. Highest cell losses were found in groups with high rates of cell proliferation. In spite of some very high rates of cell loss, this parameter does not seem to explain by itself the differences in growth rates of the various groups.