COULD injecting vitamin C into the blood help to treat cancer?
That鈥檚 what a study in mice suggests 鈥� and trials are already under way to test such injections in people. But the preliminary result could prompt desperate patients to take large doses of the vitamin, which some cancer specialists fear may interfere with standard cancer drugs and radiation therapy, reducing their effectiveness.
Excitement over vitamin C as a cancer treatment grew in the 1970s after the Nobel prizewinning chemist Linus Pauling suggested that it extended the lives of terminally ill patients. In 1985, however, two trials found that taking vitamin C pills orally had no effect.
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Now a team led by of the National Institute of Diabetes and Digestive and Kidney Diseases in Bethesda, Maryland, is investigating the effects of injecting vitamin C into the bloodstream.
First they injected mice with cells from three aggressive human cancers 鈥� ovarian and pancreatic tumours, plus a form of brain cancer called glioblastoma. When they then injected some of the mice with vitamin C, they found that tumour growth slowed by up to 53 per cent compared withthe controls (Proceedings of the National Academy of Sciences, ).
鈥淲hen the team injected some of the mice with vitamin C, tumour growth slowed by up to 53 per cent compared with controls鈥�
Levine explains that larger amounts of vitamin reach the tumour when it is injected compared with when it is taken orally. And while vitamin C usually acts as an antioxidant, in these large amounts it causes the formation of hydrogen peroxide 鈥� a powerful oxidising agent that kills cancer cells. He suggests that intravenous vitamin C could be a useful addition to conventional cancer therapy.
Women with cancer have already received intravenous vitamin C in a led by Jeanne Drisko of the University of Kansas in Kansas City. The trial was run to test the safety of injected vitamin C, plus other antioxidants taken orally, on top of standard therapies for cancers of the ovaries, cervix and uterus. Drisko is still analysing the results, although her clinic already offers intravenous vitamin C to paying patients. Meanwhile, the Cancer Treatment Centers of America in Zion, Illinois, is in late-stage cancer patients who have no other treatment options.
Definitive answers will only come from subsequent larger trials. However, given recent reactions to a drug called DCA, which some patients began taking without medical supervision after reading about promising results on cancer cells, patients may take matters into their own hands. This could be dangerous. 鈥淚 would not recommend that people inject themselves with vitamin C,鈥� says Len Lichtenfeld of the American Cancer Society in Atlanta, Georgia.
Nor should they take large doses of vitamin C in pill form, says David Agus, an oncologist at the Cedars-Sinai Medical Center in Los Angeles, California. Drisko and other supporters of complementary approaches suggest that antioxidant vitamins can aid cancer therapy and reduce side effects. Indeed, many cancer patients take antioxidant vitamins without telling their doctors. But conventional chemotherapy and radiotherapy are thought to work in part by generating free radicals which kill cancer cells. Because antioxidant vitamins can mop up these radicals, they may interfere with cancer therapy. 鈥淵ou want to make sure you鈥檙e not taking supplemental vitamins,鈥� says Agus.
Cancer 鈥� Learn more about one of the world鈥檚 biggest killers in our comprehensive special report.
