Max Gerson immigrated to the United States from Germany. In 1938, after passing the New York state medical board examinations, he started a practice in New York City. While in Germany, Gerson had suffered from severe migraine headaches and developed a vegetarian diet as a way to cure his migraines. The diet was based on his study of the history of medicine and his respect for the writings of Paracelsus (1490-1541), who said that diet must be the basis of medical therapy; however, Gerson noted that diet is only one part of a treatment regimen.  The special diet cured his migraines, and after seeing its success in one of his patients suffering from lupus vulgaris, he prescribed the diet for others suffering from the same disease. He conducted a successful clinical trial in Germany using the vegetarian diet. His most noted patient was the wife of Albert Schweitzer, M.D., whom he reported curing. The accolades he received from Dr. Schweitzer may have persuaded the medical community to seriously consider the Gerson therapy and perhaps led to Gerson's 1946 appearance with five of his patients before a congressional committee considering a bill to increase funding for cancer research.
When Gerson began prescribing his regimen for patients, he did not consider his therapy a cure for cancer. At that time he wrote that there was no conclusive evidence from his work that cancer was influenced by diet; however, he did think that diet was a useful supportive measure. In 1958, after treating patients with his regimen for more than 15 years, Gerson published his complete theory, including the results of 50 cases. He started referring to his regimen as an "effective treatment for cancer, even in advanced cases."[1,4]
Cancer prevention is action taken to lower the chance of getting cancer. By preventing cancer, the number of new cases of cancer in a group or population is lowered. Hopefully, this will lower the number of deaths caused by cancer.
To prevent new cancers from starting, scientists look at risk factors and protective factors. Anything that increases your chance of developing cancer is called a cancer risk factor; anything that decreases your chance of developing cancer is called a cancer protective...
The practice of changing diet or fasting to cure or ameliorate the effects of disease has a long history, as does the practice of giving enemas to flush the body, thus keeping the body clear of toxins.  There are no reported results of clinical trials examining the efficacy of either of these practices in the treatment of cancer or how these practices would affect a treatment. Evolving evidence supports the idea that a plant-based diet plays a role in cancer prevention.