Dr. Otto Warburg’s Address to Nobel Laureates, June 30, 1966 at Lindau, Lake Constance, Germany “There are prime and secondary causes of diseases. For example, the prime cause of the plague is the plague bacillus, but secondary causes of the plague are filth, rats, and the fleas that transfer the plague bacillus from rats to man. By the prime cause of a disease, I mean one that is found in every case of the disease. Cancer, above all other diseases, has countless secondary causes. Almost anything can cause cancer. But, even for cancer, there is only one prime cause. The prime cause of cancer is the replacement of the respiration of oxygen … in normal body cells by fermentation of sugar.