Vitamin C may boost chemotherapy

Date: Feb-10-2014A new study suggests giving some cancer patients high doses of vitamin

C intravenously - as opposed to orally - alongside conventional chemotherapy, may help kill

cancer cells and also reduce some of its toxic side effects.

Reporting their findings in Science Translational Medicine, researchers from the

University of Kansas (KU) Medical Center describe how they tested the approach in

cells, animals and humans.

They found giving infused vitamin C together with carboplatin and paclitaxel - two

conventional chemotherapy drugs - stopped ovarian cancer in the lab and also reduced toxic side

effects of chemotherapy in ovarian cancer patients.

Since the 1970s, ascorbate - or vitamin C - has been used as an alternative therapy for cancer.

It has an "outstanding safety profile," write the researchers, who also note there were

anecdotal reports that it was effective if given intravenously.

However, although complementary and alternative therapy doctors continued to use it to

combat cancer, conventional oncologists abandoned its use after clinical trials of orally administered vitamin C found it was ineffective against cancer.

Now, more recent studies have resurrected the possibility that intravenous vitamin C may be

worth looking at again as a possible anti-cancer therapy, so the KU researchers decided to

investigate.

Given intravenously, vitamin C has anti-cancer effects

And indeed, what they found was that vitamin C can be effective against cancer when given

intravenously, as senior author Qi Chen, assistant professor in the Department of Pharmacology,

Toxicology and Therapeutics at the KU Medical Center, explains:

"What we've discovered is that, because of its pharmacokinetic differences, intravenous

vitamin C, as opposed to oral vitamin C, kills some cancer cells without harming normal

tissues."

For their clinical trial, the researchers recruited 27 patients who had just been diagnosed

with stage 3 or stage 4 ovarian cancer.

They all underwent conventional chemotherapy with paclitaxel or carboplatin, but some also

received high doses of vitamin C intravenously. They were then followed for 5 years.

The researchers found that, compared with the patients who did not receive vitamin C in addition to

conventional chemotherapy, the toxic effects of the therapy tended to be less in the patients

given vitamin C.

In another experiment, the researchers found vitamin C killed cancer cells in mice with

ovarian cancer, but only at concentrations that can be achieved if given intravenously. They noticed no toxic effects or changes due to chemotherapy in the animals' livers, kidneys and

spleens.

When they looked at what was happening at the molecular level, they found vitamin C in the

fluid surrounding tumor cells acts as a "pro-oxidant," spurring formation of hydrogen peroxide,

which kills cancer cells.

On further investigation of this path, the researchers found a number of mechanisms through

which, acting as a pro-oxidant, vitamin C induced cell death in ovarian cancer cells, including

promoting damage to their DNA, without affecting healthy tissue.

Researchers call for large clinical trials

Co-researcher Dr. Jeanne Drisko, who specializes in integrative medicine at KU,

says:

"We now have a better understanding of vitamin C's anti-cancer action, plus a clear safety

profile, and biological and clinical plausibility with a firm foundation to proceed. Taken

together, our data provide strong evidence to justify larger and robust clinical trials to

definitively examine the benefit of adding vitamin C to conventional chemotherapy."

However, it may not be easy to find funding for large clinical trials of intravenous vitamin

C. Pharmaceutical companies, for example, are unlikely to be interested because with vitamin C

being a natural substance, they would not be able to patent it.

Meanwhile, Medical News Today reported a study that suggests athletes should avoid supplementing

with vitamin C and vitamin E as it may hamper their endurance training.

Written by Catharine Paddock PhD




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