Despite his diagnosis, Jobs resisted his doctors' recommendations for medical intervention for nine months,[117] instead relying on a pseudo-medicine diet to try natural healing to thwart the disease. According to Harvard researcher Ramzi Amri, his choice of alternative treatment "led to an unnecessarily early death".[114] Other doctors agree that Jobs's diet was insufficient to address his disease. Cancer researcher and alternative medicine critic David Gorski, for instance, said, "My best guess was that Jobs probably only modestly decreased his chances of survival, if that."[118] Barrie R. Cassileth, the chief of Memorial Sloan Kettering Cancer Center's integrative medicine department,[119] said, "Jobs's faith in alternative medicine likely cost him his life.... He had the only kind of pancreatic cancer that is treatable and curable.... He essentially committed suicide."[120] According to Jobs's biographer, Walter Isaacson, "for nine months he refused to undergo surgery for his pancreatic cancer – a decision he later regretted as his health declined".[121] "Instead, he tried a vegan diet, acupuncture, herbal remedies, and other treatments he found online, and even consulted a psychic. He was also influenced by a doctor who ran a clinic that advised juice fasts, bowel cleansings and other unproven approaches, before finally having surgery in July 2004."[122]