He didn't use placebos?
The claim that vitamin C is useful in the treatment of cancer is largely attributable to Linus Pauling, Ph.D. During the mid-1970s, Pauling began claiming that high doses of vitamin C are effective in preventing and curing cancer. In 1976 and 1978, he and a Scottish surgeon, Ewan Cameron, reported that a group of 100 terminal cancer patients treated with 10,000 mg of vitamin C daily had survived three to four times longer than historically matched patients who did not receive vitamin C supplements [61-62]. However, Dr. William DeWys, chief of clinical investigations at the NCI, found that the patient groups were not comparable. The vitamin C patients were Cameron's, while the other patients were managed by other physicians. Cameron's patients were started on vitamin C when he labeled them "untreatable" by other methods, and their subsequent survival was compared to the survival of the "control" patients after they were labeled untreatable by their doctors. DeWys found that Cameron's patients were labeled untreatable much earlier in the course of their disease-which meant that they entered the hospital before they were as sick as the other doctors' patients and would naturally be expected to live longer [63]. Nevertheless, to test whether Pauling might be correct, the Mayo Clinic conducted three double-blind studies involving a total of 367 patients with advanced cancer. All three studies found that patients given 10 g of vitamin C daily did no better than those given a placebo [64-66]. Despite many years of taking huge daily amounts of vitamin C, both Pauling and his wife Ava died of cancer -- she in 1981 and he in 1994.
61. Cameron E, Pauling L. Supplemental ascorbate in the supportive treatment of cancer: prolongation of survival times in terminal human cancer. Proceeding of the National Academy of Sciences 73:3685-3689, 1976.
62. Cameron E, Pauling L. Supplemental ascorbate in the supportive treatment of cancer: reevaluation of prolongation of survival times in terminal human cancer. Proceeding of the National Academy of Sciences 75:4538-4542, 1978.
63. DeWys WD. How to evaluate a new treatment for cancer. Your Patient and Cancer 2(5):31-36, 1982.
64. Creagan ET and others. Failure of high-dose vitamin C (ascorbic acid) therapy to benefit patients with advanced cancer. A controlled trial. New England Journal of Medicine 301:687-690, 1979.
65. Moertel CG and others. High-dose vitamin C versus placebo in the treatment of patients with advanced cancer who have had no prior chemotherapy. A randomized double-blind comparison. New England Journal of Medicine 312:137-141, 1985.
66. Tschetter L and others. A community-based study of vitamin C (ascorbic acid) in patients with advanced cancer. Proceedings of the American Society of Clinical Oncology 2:92, 1983.