A diabetes treatment drug called Metformin has been around for years. It is sold under the names of Glucophage and Fortamet. While it has long enjoyed a favorable safety profile, it got displaced in the marketplace by newer drugs that were under patent and therefore more promoted by the pharmaceutical companies. These newer drugs turned out to have problems, for examples see all the litigation surrounding Actos (causing bladder cancer), Avandia (causing heart attacks) and Rezulin (causing liver damage). Now, there are new studies showing that Metformin actually extended the survival rates in patients with ovarian cancer.
So in the interest of increased profits, patients were led away from a drug which benefits cancer patients to one that causes cancer. Irony aside, these new studies show real promise for the clinical use of Metformin in cancer patients. It is believed that Metformin inhibits tumor growth by starving the tumor cells of glucose. Further research is already underway at the Mayo Clinic.