Changes of Vascular Pattern of Tumors and Surrounding Tissue During Different Phases of Metastatic Growth

Abstract

The vascular systems of metastases exhibit changes with increasing growth. These changes in the vascular systems depend on certain factors in the surrounding tissue, i. e., in the parent tissue of the metastases, and on the specific characteristics of the malignant tumor. These various factors are as follows:

• 1. Histological type of metastasis

• 2. Histological degree of differentiation

• 3. Rate of growth

• 4. Induction of stroma

• 5. Incidence of necrosis

• 6. Location of the organ

• 7. Preexisting vascular structures or, as the case may be, relationship to the vascular system in the host organ

The growth of malignant tumors — and this applies to metastases as well, of course — is inconceivable without their own vascular system, i. e., without neoangiogenesis in the tumor. There is no doubt that in practice every growing tumor sooner or later produces angiogenetic stimuli which lead to neoangiogenesis [9]. The process of angiogenesis in metastases does not begin immediately after the invasion of the first tumor cells into the host organ [2]. This may constitute a difference from angiogenesis in primary tumors, which mostly develop out of preneoplasia and which, already in that form, exhibit characteristic changes in the vascular system [10].