Vitamin C as Cancer Treatment The use of vitamin C in the treatment of cancer has been the source of many claims and controversies over the last 25 years. Initial reports from Drs. Pauling and Cameron were promising, and gained much notoriety. They reported 100 cases of terminal cancer, independently assessed and refractory to conventional treatment, who lived on average four times longer than 1000 age and disease-matched controls.59 The protocol included intravenous and oral administration, and is described in detail elsewhere.60 Prospective randomized trials held at the Mayo Clinic were unable to replicate these results, finding negligible difference between treated patients and controls in survival time.61,62 These results were criticized on a number of grounds, including the noticeable difference between the vitamin C and placebo, lack of intravenous administration, and termination of treatment with tumor progression.60 Later in vitro and in vivo research, and well documented case reports,63 suggest a vitamin C dose much higher than that used in the Pauling/Cameron studies can actually be cytotoxic to tumors without damaging normal cells. The required tissue concentrations are thought to only be reachable with intravenous doses over long periods of time. This research, as well as the proposed mechanism of action, is examined elsewhere.64 Vitamin C is generally well-tolerated by healthy people, even in doses as high as 200 g/day IV.64,65 Dr. Cameron has noted that a small percentage of cancer patients will respond to vitamin C with rapidly proliferating and disseminating tumors.66 Other investigators have not noted this effect. Vitamin C with Radiation Quite surprisingly, no published studies have looked at the effect of doses over five grams of oral or intravenous vitamin C on radiotherapy in humans. It has been shown, however, that cancer patients have a significant elevation in plasma and leukocyte ascorbate levels after radiotherapy compared with pretreatment levels without any change in dietary intake.67 In mice, vitamin C (1 g/kg), given intraperitoneally with vitamin K3 (10 mg/kg), increased the therapeutic effect of radiation on solid tumors without causing any signs of toxicity due to the vitamins.68 In another mouse study, a single intraperitoneal dose of 4.5 g/kg vitamin C was not cytotoxic to normal tissue and did not change the radiation effect on tumor tissue. The lethal dose of radiation increased and skin desquamation reaction was reduced by ascorbate treatment. It should be noted that these vitamin C doses are much greater than have been used historically in humans.69 The radioprotection of healthy tissue and radiosensitizing effect in tumors with use of ascorbate were confirmed in two other mouse tumor models.70,71 A randomized trial with 50 human subjects looked at the effect of concurrent vitamin C (five daily doses of 1 g each) and radiotherapy on different tumor types. More complete responses to radiation were noted in the vitamin C group at one month (87% to 55%) and four months (63% to 45%) post treatment. Side effects tended to be fewer in the ascorbate-treated subjects as well. Plasma levels of ascorbate in the treatment group were greater than control subjects, but less than the mean of 20 healthy subjects tested.72 It remains to be investigated whether continuing treatment beyond the end of radiotherapy or use of a higher dose would improve these results. A double-blind trial of topical vitamin C solution for the prevention of radiation dermatitis failed to find any beneficial effect. The trial did not examine the absorption of the aqueous preparation, although previous trials showed about 12 percent of the vitamin C penetrated into the epidermis.73 Vitamin C with Chemotherapy Vitamin C has been extensively tested in vitro and in vivo for its ability to prevent the adverse effects of, decrease resistance to, and increase the effects of chemotherapeutic agents. Co-treatment with doxorubicin and vitamin C (2 mg/kg) led to a reduction in the toxicity seen with doxorubicin alone in mice and guinea pigs. The prevention of cardiomyopathy was confirmed by electron microscopy. Treatment with ascorbic acid was not associated with decreased effect of doxorubicin, and was associated with an increased life span compared with doxorubicin treatment alone.11 In vitro experiments do suggest, however, that vitamin C does enhance doxorubicin resistance in human breast cancer cell lines already known to be resistant. It did not lead to resistance in cells which were doxorubicin-sensitive.74 Vitamin C at non-cytotoxic concentrations (1 mM) increased the activity of doxorubicin, cisplatin, and paclitaxel in human breast carcinoma cells in vitro. T his effect was particularly marked and synergistic with doxorubicin. The authors note that since vitamin C has already shown an ability to reduce the cardiotoxicity of doxorubicin, ascorbic acid and doxorubicin are an attractive future treatment for breast cancer.75 Vitamin C has been shown to increase the drug accumulation and decrease resistance to vincristine in human non-small-cell lung cancer cells in vitro. An ascorbic acid-sensitive uptake mechanism was theorized to explain these results.76 Combined intraperitoneal administration of vitamin C (1g/kg) and vitamin K (10 mg/kg) given prior to chemotherapy increased survival and the effect of several chemotherapeutic agents (cyclophosphamide, vinblastine, doxorubicin, 5-fluorouracil, procarbazine, and asparaginase) in a murine ascitic liver tumor model. The vitamin combination did not increase the toxicity of these agents to healthy tissue. Splenic and thymic weights of the vitamin-treated animals were higher than those receiving cytotoxic treatment alone, suggesting an immune-stimulating action of the vitamins.12 These results have yet to be confirmed in humans. Alternative Medicine Reviews, 1999;4(5):304-329. Remember we are NOT Doctors and have NO medical training. This site is like an Encylopedia - there are many pages, many links on many topics. Support our work with any size DONATION - see left side of any page - for how to donate. 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