The reason our medieval doctors will probably never find a cure for cancer is because cancer is the symptom, not the disease. Cancer, as with virtually all non-contagious diseases, can be classified as the diseases of the soul, but in reality are the results of chakra blockages within the body (Modern medicine has yet to learn about this fact and may never). These blockages are caused by many reasons, such as seeking power, unpure thoughts, greed, envy, gluttony, and so on... Cancer can ONLY be cured by the patient who seeks a lifestyle change, and is why so often is reoccurring. The fastest and most effective cure for any type of disease is long term fasting, in which spiritual enlightenment is achieved.
This is why some people, such as my grandfather, who smoked unfiltered tobacco in a pipe and drank whiskey like water, died at the age of 93 singing in his recliner without any disease or pain. He was a good man with some very bad habits. Take a close look at all that have cancer, diabetes, ect.. and you will find that they all share something in common, not living as God intended. These diseases are NOT punishment by our LOVING Creator GOD, but merely a warning for those not on the right path. You might be asking yourself, "what about the children who are struck with a terrible disease?" Unfortunately, they are suffering from previous incarnations and are here to learn their life lessons too.
This is also why all medicines have bad side effects, and if at all possible, should not be used as a treatment for anything. Chemicals are not the proper way to heal the body and mind, God-source energy is. If a person truly wants to be healthy, then the mind/body/spirit complex must be connected to God-source via the sixth chakra (third eye). There are many good books on how to activate the seven chakras of the body (though in actuality there are 15)
Try to find a person who has opened their chakras that is suffering from a disease. You will not find one.
Try to maintain an alkaline based diet. Edgar Cayce wrote very good book on the subject of Diet and Health.
Find love in everything, be in harmony with Mother Earth and meditate often.