A number of studies have shown that the extracellular pH in cancers is typically lower than that in normal tissue and that an acidic pH promotes invasive tumor growth in primary and metastatic cancers. The external pH of solid tumors is acidic as a consequence of increased metabolism of glucose and poor perfusion. Acid pH has been shown to stimulate tumor cell invasion and metastasis in vitro and in cells before tail vein injection in vivo.
Dr. Robert J. Gillies from Wayne State University School of Medicine paper, “Acidity generated by the tumor microenvironment drives local invasion. The pH of solid tumors is acidic due to increased fermentative metabolism and poor perfusion. In every case, the peritumoral pH was acidic and heterogeneous and the regions of highest tumor invasion corresponded to areas of lowest pH. Tumor invasion did not occur into regions with normal or near-normal pH. In support of the functional importance of our findings, oral administration of sodium bicarbonate was sufficient to increase peritumoral pH and inhibit tumor growth and local invasion in a preclinical model, supporting the acid-mediated invasion hypothesis.”