The Role of Antioxidants in Cancer Treatment

I have great respect for Dr Ralph Moss, author of' The Moss Reports, regular updates on cancer treatment.

Here's some of what he has to say:

"There are few issues in cancer therapy so surrounded by confusion as the question of whether or not cancer patients should continue to take antioxidant supplements during radiation treatment.

Prompted by the many questions I receive from clients on this topic, I am now offering two investigative reports on the subject. The first of these - Do Antioxidants Interfere With Radiation Treatment for Cancer? - is designed to help patients make sense of the conflicting information they are likely to encounter on this issue. This 26 page report contains up-to-the-minute information concerning the controversial question of whether antioxidants can safely be taken during radiation treatment, and includes new research data that more clearly identifies which patients are most likely to be affected by potential interactions.

Because the question of antioxidant use is an area of such vital importance to cancer patients, we are also offering this new report packaged with our earlier report on the use of antioxidants during cancer therapy. This combined report, 83 pages in length, offers an exhaustive discussion of the topic, covering the use of supplemental antioxidants during both chemotherapy and radiation.

For further details and information on purchasing either the single or the combined report please scroll down to the end of the newsletter.

An important paper on the interaction of antioxidants and radiation therapy was recently published in the International Journal of Cancer. Interestingly, despite the significance of its findings, this study has received virtually zero attention from the scientific community or the media.

As background, in April 2005, Isabelle Bairati, MD, PhD, and her colleagues at the Hôtel-Dieu de Quebec Research Centre and the Universite Laval completed a ten-year study on the interaction of antioxidants and radiation therapy. This was hailed as the first placebo-controlled, double-blind, randomized trial assessing the effect of supplementation with antioxidant vitamins during radiation therapy. The study concluded that supplements of synthetic beta-carotene (30 mg per day) or alpha tocopherol (400 IU per day) had a harmful effect on cancer patients. In particular, the authors claimed that the cancer recurrence rate was 40 percent higher among patients who had been randomly assigned to the supplementation arm of the trial. They therefore called on patients and physicians to exert caution in using antioxidants until new evidence could be provided by future trials.

Kedar Prasad, PhD, and other proponents of the concurrent use of antioxidants during cancer treatment criticized the Bairati paper. They were disappointed that Bairati and colleagues had used ordinary alpha tocopherol as their choice of vitamin E when Prasad's previous work had shown that it was not just alpha tocopherol but alpha tocopherol succinate that had the anticancer efficacy. They also felt that natural forms of the vitamin were more effective than synthetic, drug store-type vitamins. But, by and large, the medical world accepted the Bairati trial as definitive proof that antioxidants interfered with radiation therapy. Word spread like wildfire in oncology circles, confirming a long-held belief that antioxidants interfered with standard cancer treatments such as radiation and chemotherapy. The take away message, as stated in a Universite Laval press release, was that "Supplements May Speed Up Development of Cancer." Advocates of complementary and alternative medicine
(CAM) were confounded by this large and impressive study.

But now the other shoe has dropped.

In December 2007, Dr. Bairati and her Quebec colleagues published a major modification of their previous conclusions. Further analysis revealed, they said, that the danger of synthetic antioxidants was limited to one particular sub-population: cigarette smokers - specifically, those who continued to smoke during radiation treatment. The authors analyzed the outcome in 540 patients who had been given radiation for head and neck cancers. During the follow-up period, 119 patients had a recurrence of their disease and 179 died. Smokers were the group with the worst prognosis. However, astonishingly, smoking in the period leading up to or following radiation therapy did not modify the effects of the two supplements. It was only smoking during the course of radiation therapy that led to a statistically significant increase in the risk of a recurrence. It was a large enough increase to skew the statistics for the group as a whole, leading to the erroneous conclusion that antioxidant s interfered with radiotherapy in the general patient population.

Statistically, increased risk is generally expressed as a "hazard ratio" (abbreviated HR). In this study, current smokers had an HR of 2.41 for recurrence, in other words more than double the chance of a recurrence compared to the rest of the patient population. The HR for death from any cause was a similar 2.26. But the hazard ratio for dying of their initial head and neck cancer was a whopping 3.38 in patients who got radiation, smoked and also received a single synthetic antioxidant.

"These results could best be explained by the hypothesis that the combined exposures reduced the efficacy of radiation therapy," Bairati and her colleagues now say. "Particular attention should be devoted to prevent patients from both smoking and taking antioxidant supplements during radiation therapy" (Meyer 2007).

According to the National Cancer Institute, 85 percent of head and neck cancers are linked to tobacco use. (Alcohol use further exacerbates this trend.) This has been widely known for years, and so it is shocking that there are still people so hopelessly addicted to tobacco that they not only continue to smoke after they've been diagnosed with head and neck cancer but continue to smoke right through their radiation therapy. It was in this subset of particularly unhealthy individuals that antioxidants were associated with an increased risk of disease progression. As Bairati and colleagues suggest, such individuals should definitely not compound their problems by then taking a synthetic antioxidant.

But the more important lesson for patients and practitioners is that antioxidants do NOT generally interfere with the effects of radiation therapy, as was previously suggested. They do NOT increase the risk of a recurrence, of death from head and neck cancer, or of overall mortality in the average patient. In this updated study, the harmful effect of synthetic antioxidants was entirely limited to those relatively few tobacco-addicted patients who continued to smoke during their radiation therapy. Thus, the major premise underpinning oncologists' condemnation of antioxidants during radiation therapy has crumbled, although few seem to have noticed so far."

If you'd like more information you can register on his site for updates. Well worth it!
Go here