Impairment of vascularization of the surface covering epithelium induces ischemia and promotes malignization: a new hypothesis of a possible mechanism of cancer pathogenesis

PURPOSE To study the peculiarities of vascularization at the stromal-epithelial interface in different types of epithelia and their alterations in precancerous lesions. MATERIALS AND METHODS Peritumoral tissues of 310 patients, tissues of 180 healthy persons and of 50 human embryos and fetuses were used. Traditional histological as well as immunohistochemical methods have been used. RESULTS The study reveals that the occurrence of blood capillaries in surface squamous epithelium is an ordinary event, both in healthy persons and in peritumoral regions of the patients with squamous cell carcinoma. Glandular epithelial coverings, as well as transitional epithelium, do not contain blood vessels. In squamous epithelium, only basal cells are in contact with the membrane and underlying stroma, the cells of the upper layer receiving nutrients through diffusion. Thus, the cells of squamous epithelium are more vulnerable to blood deficiency, since for instance in the pseudo-multilayered respiratory epithelium each cell is attached directly to the basal membrane and has more ample access to the blood supply. Metaplastic squamous epithelium has a markedly reduced vascularization and seems to be more sensitive to carcinogenic stimuli. High-grade dysplastic squamous epithelium and carcinoma in situ do not contain blood vessels. CONCLUSION The process of redistribution of vascular network occurring at the interface of epithelial-stromal frontier plays an important role in maintaining the adequate metabolism of cells including those of epithelial covering. Impairment of this mechanism most probably promotes precancerous alterations.