Critical evaluation of histochemical and immunochemical methods for the demonstration of vascular supply in rectal and oesophageal cancer.

The vascularisation of rectal and oesophageal carcinomas and of normal mucosa was studied using histochemical and immunohistochemical methods. Endothelial cells were stained for alkaline phosphatase (AP) using an azo-dye procedure. Histochemical results were compared with the immunohistochemical identification of endothelial cells using the monoclonal antibody BW 200 recognising an epitope restricted to human endothelial cells. In the AP experiments the simultaneous reactivity of stromal tissue often precluded the exact evaluation of tumour blood vessels. Immunohistochemistry facilitated the identification of vessels in neoplastic tissues and allowed a quantitative analysis of vascular volume by means of point-counting. Vascular volumes of normal tissues exceeded those of tumours by a factor of 1.6. This immunohistochemical technique has potential application in studying the importance of tumour blood supply in man, especially in relation to radiotherapy.