Apoptosis and cellular proliferation in oesophageal squamous cell carcinomas: differences between keratinizing and...

To assess cell death and cellular proliferation activity, the apoptosis index, the Ki67 proliferative index and overexpression of p53 protein were evaluated in 69 oesophageal squamous cell carcinomas (ESCC), all surgically resected from Japanese patients. Apoptosis was examined by Gavrieli's method in histological sections, and proved to be significantly related to keratinization and ESCC progression. Overall labelling indices were 15.68 +/- 4.04 (positive/1,000 nuclei) and 6.79 +/- 0.64 respectively, in keratinizing and nonkeratinizing types. The apoptosis labelling index increased, especially in keratinizing lesions, from 4.50 +/- 0.59 with cancer invasion to mucosa through 11.46 +/- 2.70 with involvement of the submucosa up to 21.18 +/- 3.72 in cases of penetration to the muscularis propria or adventitia. The relationship between apoptosis, Ki67 scores and p53 expression was determined in identical cancer nests on serial sections. An inverse correlation was shown between the apoptosis score and the Ki67 score in both keratinizing and nonkeratinizing types. There was no significant correlation between apoptosis score and p53 expression, either overall or separately in keratinizing or nonkeratinizing types of ESCC. Our results suggest that a mechanism of induction of apoptosis similar to that operating in normal epidermis acts in keratinizing ESCC, and that as tumour volume increases, single cell death becomes more frequent.