Cesium is a rare, naturally occurring element of alkali metal, similar in chemical structure to lithium, sodium, and potassium. Cesium chloride is a salt form of this element. Cesium chloride is most commonly associated with High pH Therapy and cancer, due to the work of Keith Brewer, Otto Warburg, and H.E.Sartori, among others. They found that cancer cells thrive in an anaerobic (low oxygen) environment with low pH values, and that raising the cell pH makes it hard for cancer cells to survive. Cesium, being one of the most alkaline elements, has a high pH value and is also readily taken up by cancer cells, thus raising their pH to a level at which they can no longer survive.