You won’t believe what interferes with chemotherapy


 A paper by Dr. Mark Heaney and colleagues published in the October issue of Cancer Research revealed a startling finding. When leukemia and lymphoma cells were exposed in the lab to dehydroascorbic acid, they were less likely to be killed by chemotherapy. Cells that had been exposed to dehydroascorbic acid were better able to survive treatment with doxorubicin, cisplatin, vincristine,methotrexate, or imatinib, five widely prescribed chemotherapy agents that act in a number of different ways.

Why should the average person care about this study? This study provides a valuable warning to cancer patients because dehydroascorbic acid is vitamin C.

In interviews, the authors were careful to point out that this is lab research taking place in petri dishes, not clinical research done in humans. However, the findings are disturbing in light of the fact that many cancer patients take vitamin C supplements. Rather than boosting the immune system, vitamin C supplements may actually boost the cancer cells.

As recently as August of this year, alternative health practitioners like Joseph Mercola, were touting high dose vitamin C supplements as highly effective against cancer. At this moment, many alternative health websites still recommend vitamin C supplements as “treatment” against cancer. The “theory” is that vitamin C, an antioxidant, interferes with the action of free radicals, chemicals known to damage cells. Supposedly, since damage to cells causes cancer, and since antioxidants prevent damage to cells, antioxidants “treat” cancer.

The irony is that vitamin C appears to act in precisely the opposite way. Yes, vitamin C is an antioxidant that reduces cellular damage from free radicals, but some chemotherapeutic agents are free radicals that kill cancer by damaging the individual cancer cells. Vitamin C supplements appear to inactivate chemotherapy, either by inactivating the drugs themselves or by interfering with the action of the drugs. Indeed, the authors found that vitamin C reduced the cancer killing ability of chemotherapy by 30-70%, depending on the chemotherapy drug.

What did the authors do in the study? The authors exposed leukemia and lymphoma cells to dehydroascorbic acid, the form of vitamin C that appears in the blood stream after taking supplements. Then they compared the effects of chemotherapy on those cells with sister cells that had not been exposed to vitamin C. They did this in two ways; first by exposing cells to chemotherapy drugs, and second by transplanting cells into mice, generating tumors, and then treating the mice with chemotherapy. In both cases, in the petri dishes and in the mice afflicted with cancer, exposure to vitamin C dramatically reduced the ability of the chemotherapy drugs to kill the cancer cells.

These findings are in keeping with a large number of studies that have shown that vitamin C can neither prevent nor treat cancer, most importantly a recently released, large scale study of vitamin C use among 14,600 male doctors participating in the Physicians Heart Study II. Participants received either vitamin C or vitamin E supplements or placebo for 10 years. The study was undertaken to look at the effects of vitamin supplements on heart disease, but the authors kept careful records of all other medical outcomes in these groups. The principle finding of the study was that vitamin C and vitamin E supplements had no effect on the risk of heart attack or stroke. A secondary finding was that vitamin C (and vitamin E) had no effect on cancer risk, either.

While cautious about the preliminary nature of the study, Dr. Heaney, the scientist who tested vitamin C on leukemia and lymphoma cells, expressed his concerns in an interview with Medscape Oncology:

“Our study is a preclinical model that addresses only the situation when vitamin C is given in the setting of chemotherapy treatment,” Dr. Heaney emphasized. There have been no clinical studies of this topic so far, he said.

However, the finding could be of potential concern because “many people, cancer patients included, take supplemental vitamin C,” Dr. Heaney pointed out. Clinical studies of vitamin C supplementation in patients with advanced cancers have had mixed results. There are conflicting hypotheses, he explained. One theory is that vitamin C supplementation protects the cancer and is therefore detrimental to the patient…

Medscape Oncology interviewed another doctor with no connection to the study:

Asked to comment on this study, Len Lichtenfeld, MACP, deputy chief medical officer at the American Cancer Society said: “Vitamin C has a long history in cancer prevention and treatment. Although there is no evidence to demonstrate that vitamin C improves the outlook for patients with cancer, there are still reported observations that cancer patients continue to believe in the potential benefits of vitamin C. Although oncologists do not routinely recommend that patients with cancer take excessive doses of vitamin C, there are reports that cancer patients are being treated with vitamin C by alternative practitioners…”

… [T]he current report suggests that in laboratory experiments, adding vitamin C to cancer cells may reduce the effectiveness of cancer chemotherapy drugs.

“Clearly, there remains an open question as to whether or not vitamin C supplementation is helpful or harmful in the treatment of patients with cancer. Until those questions are resolved with further clinical studies, it would be inappropriate to recommend that patients take large quantities of vitamin C if they have cancer,”

Many cancer patients explore alternative treatments like vitamin supplementation, reasoning that while they may not be help, they are not likely to be harmful. This study demonstrates that such assumptions may be totally false. Supplements like vitamins and herbs have chemical actions of their own, and those chemical actions may interfere with the effectiveness of conventional treatment, or inadvertently improve the survival ability of the cancer, not the patient.

The most important message to take away from this study is that no one should take alternative treatments of any kind without discussing them with their doctor, to be sure that there are no harmful interactions. It would be tragically ironic if cancer patients were actually supplementing their cancer, instead of fortifying themselves for the fight against the disease.