As reported in the Fall/Winter 2005 LPI Research Report ("Vitamin C and Cancer—Renewed Interest"), vitamin C has re-emerged as a promising substance in the adjunctive treatment of cancer, 35 years after the beginning of the productive collaboration between Drs. Ewan Cameron and Linus Pauling. Cameron gave high-dose vitamin C intravenously and orally to terminal cancer patients, many of whom reported an increased sense of well-being and lived longer than expected. Cameron and Pauling documented their observations in a series of technical papers and a book for the public, Cancer and Vitamin C. Recent work by Dr. Mark Levine and colleagues at the National Institutes of Health continued to demonstrate the efficacy of high concentrations of vitamin C in killing cancer cells in vitro and emphasized the potential value of attaining these high concentrations in the body by intravenous, rather than oral, administration.
A new study by Dr. Levine and colleagues was published in the Canadian Medical Association Journal in March 2006. In this study, the investigators carefully reviewed the clinical cases of three patients who responded especially favorably to high-dose intravenous vitamin C in an attempt to assess the clinical plausibility of this modality in cancer therapy. To accomplish this, the investigators followed the National Cancer Institute Best Case Series guidelines in their analysis. One case involved renal cancer with lung metastases that regressed following the intravenous administration of 65 grams of vitamin C twice per week for ten months. The second patient had invasive bladder cancer. He received 30 grams of vitamin C intravenously twice per week for three months, followed by somewhat irregular infusions for about four years. The third patient had B-cell lymphoma and received 15 grams of intravenous vitamin C twice per week for two months, followed by similar doses given less frequently. All three patients experienced complete remissions. Additionally, Dr. Drisko and colleagues at the University of Kansas reported in the Journal of the American College of Nutrition in 2003 two cases of women with late-stage ovarian cancer who experienced complete remissions after receiving 60 grams of intravenous vitamin C twice per week. While not providing definitive proof that only vitamin C was responsible for these responses, the cases nonetheless suggest that the use of high-dose intravenous vitamin C should be evaluated in controlled clinical trials.
Presently, it is impossible to reliably predict which cancers and at what stage may be most sensitive to vitamin C or the magnitude of its benefit. Cameron and Pauling estimated that about 10% of patients with advanced cancer who take high-dose vitamin C would experience tumor regression or tumor death. Controlled clinical trials will help expand our knowledge in this area.
Clinical trials to test new drugs or therapies proceed in stages. A Phase I trial enrolls a small group of patients (typically 20-80) to evaluate safety, side effects, and dosage, and to gain insights into mechanism of action and efficacy. Results from these trials permit the appropriate design of Phase II trials, which involve more subjects (a few hundred) to further assess side effects and get preliminary information on effectiveness. If the results of this phase are promising, the final trial, Phase III, may be initiated. This trial enrolls more subjects (hundreds or thousands) to address efficacy and evaluate overall risks and benefits.
A Phase I clinical trial of intravenous vitamin C alone or in combination with chemotherapy is under way at McGill University in Montreal. Additionally, a small-scale Phase I trial was published by Dr. Hugh Riordan and colleagues in December 2005. In that trial, 24 late-stage cancer patients were given high-dose intravenous vitamin C for up to eight weeks to ascertain safety and side effects. Only minor adverse effects were observed, except for one patient with a prior history of kidney stones who developed one after 13 days of therapy, suggesting that high-dose intravenous vitamin C is generally safe unless there is a predisposition to kidney stone formation.
Last updated June, 2006