Delivering high levels of Vitamin C to a cancer patient’s bloodstream may promote anti-cancer activity in the body, according to new research from the Cancer Treatment Centres of America (CTCA).

The research, which is published in the May 2013 edition of journal Cancer Chemotherapy and Pharmacology, showed that, when administered intravenously (by IV) at high doses, Vitamin C appeared to inhibit the rate of tumour growth in mice.

The use of Vitamin C to treat cancer patients first became popular in the 1970s as a result of the work of Nobel Laureate Linus Pauling. Studies conducted with orally dosed patients, however, did not demonstrate any clinical benefit in cancer patients, most likely because the levels of orally-administered vitamin C delivered to a patient’s blood stream were considerably lower than the levels needed to kill cancer cells in either test tube or animal models.

One previous study stopped Vitamin C dose escalation at approximately 56 g/m2, when peak blood levels approached 26 mM, a level that inhibited tumour growth in mice. However, 30-40 mM ascorbic acid in mouse blood only partially inhibited the rate of tumour growth and did not result in tumour regression.

The newest research, which was led by Robert Levin MD and Christopher M. Stephenson, DO, aimed to obtain even higher blood concentrations. Their 70-80 g/m2 dose delivered blood concentrations of 49 mM. These levels appeared to have greater potential for producing anti-cancer activity in future studies.

“While this may be the baseline for treatment potential, it suggests we are on the right track for future studies and eventual use in fighting cancer,” said Dr Stephenson.

Other anti-cancer Vitamin C studies

The use of IV-administered Vitamin C in combination with cytotoxic chemotherapy is further encouraged by other recent studies.

One recent report showed that Vitamin C made anti-tumour activity of anti-cancer treatment gemcitabine more potent against seven human and one murine pancreatic cancer cell lines.

Another recently published phase one clinical trial evaluated IV-administered Vitamin C combined with gemcitabine and erlotinib in nine patients with stage four metastatic pancreatic cancer. Pharmacologic levels of Vitamin C were potentially achieved in all participants in this study, and tumour volumes decreased in eight out of nine patients.

The CTCA said its study, coupled with the emerging evidence from the available literature, suggested that the combination of IV-administered Vitamin C with gemcitabine to treat pancreatic cancer is “a therapeutic approach that warrants further evaluation”. In order to better understand the possible outcome of this increased dosage, the CTCA research team is planning to conduct a phase two study using the higher dose of 70-80 g/m2 to achieve more adequate and longer lasting blood concentrations of Vitamin C.