His studies revealed that the blood and lymphatic vasculature, fibroblasts, immune cells and the extracellular matrix associated with tumors are abnormal, collectively creating
a hostile tumor microenvironment characterized by hypoxia, low pH and high interstitial fluid pressure.
But following the removal of the primary
tumor, micrometastatic cells learn to communicate with cells in their new
microenvironment in the brain — cells which are, at first,
hostile to them.