Hepatocellular carcinomas with a high proliferation index and a low degree of apoptosis and necrosis are associated with a shortened survival

Abstract

In this study we investigated tumour growth in relation to the immunohistochemical expression of p53 and bcl-2 and to patient survival data in 33 operated hepatocellular carcinomas (HCCs). In order to estimate the growth, a growth index, based on the degree of cell proliferation, apoptosis and necrosis, was calculated for each tumour. Cell proliferation was determined immunohistochemically by the number of proliferating cell nuclear antigen (PCNA)-positive cells in tumours, the extent of apoptosis was determined by counting the number of cells labelled by the in situ 3'-end labelling technique and tumour necrosis was estimated as the percentage of necrotic areas in haematoxylin--eosin-stained tissue sections. In our analysis we found that the survival of patients with HCCs showing a high growth index (i.e. tumours showing a high proliferation and simultaneously a low degree of apoptosis and necrosis) was significantly shorter than with other patients (P = 0.004, log-rank test). When analysed separately, cell proliferation, apoptosis or necrosis did not show any significant association with survival. p53 positivity was found in 8/33 (24%) of tumours. There were significantly more p53-positive cases in tumours with a high growth index (P = 0.01, Fisher's exact test) suggesting that dysfunction of the p53 gene may affect tumour growth. p53-positive cases did not, however, have a significantly shorter survival time than p53-negative cases (P = 0.3, log-rank test). bcl-2 positivity was found in only 1/33 (3%) of the HCCs. Thus bcl-2 overexpression does not seem to play an important role in hepatocellular carcinogenesis. In summary, our results suggest that in HCCs a compound score based on the evaluation of the degree of cell proliferation, apoptosis and necrosis is a biologically more relevant prognostic indicator than any of its composite parameters alone.