Several advances have recently expanded models of
tumor growth and promoted the concept of
tumor homeostasis, the hypothesis that primary
tumors exert an anti-proliferative effect on both themselves and subclinical secondary
metastases. Recent trials indicate that the characterization of
tumor growth as uncontrolled is inconsistent with animal models, clinical models, and epidemiological models. There is a growing body of evidence which lends support to an updated concept of
tumor growth:
tumor homeostasis. In the case of
breast cancer, if not all metastasizing
tumors, these advances suggest an inconvenient truth. That is, if
breast tumor cells metastasize to distant sites early in the
tumorigenesis process, then removal of a
breast tumor may hasten the development of its
metastases. We explore the heretofore unappreciated notion that
nucleotides generated by
tumor cells following the secretion of an
ADP-kinase can promote
metastasis and support angiogenesis. Evidence is presented that blockade of the actions of
nucleotides in the setting of newly diagnosed
breast cancer may provide a useful adjunct to current anti-angiogenesis treatment.