Comments on “Mega-Dose Vitamins and Minerals in the Treatment of Nonmetastatic Breast Cancer: An Historical Cohort Study”

Should Patients Undergoing Chemotherapy and Radiotherapy Be Prescribed Antioxidants?

In September 2005, CA: A Cancer Journal for Clinicians published a warning by Gabriella D’Andrea, MD, against the concurrent use of antioxidants with radiotherapy and chemotherapy. However, several deficiencies of the CA article soon became apparent, not least the selective omission of prominent studies that contradicted the author’s conclusions. While acknowledging that only large-scale, randomized trials could provide a valid basis for therapeutic recommendations, the author sometimes relied on laboratory rather than clinical data to support her claim that harm resulted from the concurrent use of antioxidants and chemotherapy. She also sometimes extrapolated from chemoprevention studies rather than those on the concurrent use of antioxidants per se. The article overstated the degree to which the laboratory data diverged in regard to the safety and efficacy of antioxidant therapy: in fact, the preponderance of data suggests a synergistic or at least harmless effect with most high-dose dietary antioxidants and chemotherapy. The practical recommendations made in the article to avoid the general class of antioxidants during chemotherapy are inconsistent, in that if antioxidants were truly a threat to the efficacy of standard therapy, antioxidant-rich foods, especially fruits and vegetables, ought also be proscribed during treatment. Yet no such recommendation is made. Furthermore, the wide-scale use by both medical and radiation oncologists of synthetic antioxidants (eg, amifostine) to control the adverse effects of cytotoxic treatments is similarly overlooked. In sum, this CA article is incomplete: there is far more information available regarding antioxidant supplements as an appropriate adjunctive cancer therapy than is acknowledged. Patients would be well advised to seek the opinion of physicians who are adequately trained and experienced in the intersection of 2 complex fields, that is, chemotherapeutics and nutritional oncology. Physicians whose goal is comprehensive cancer therapy should refer their patients to qualified integrative practitioners who have such training and expertise to guide patients. A blanket rejection of the concurrent use of antioxidants with chemotherapy is not justified by the preponderance of evidence at this time and serves neither the scientific community nor cancer patients.

Controlling hyperglycemia as an adjunct to cancer therapy

Hyperglycemia is commonly manifested in cancer patients. Although high intakes of sugar and refined carbohydrates and elevated blood glucose are strongly associated with the risk of cancer, much less is known about their effects on survival after cancer diagnosis. There is evidence that high carbohydrate intake is associated with poorer survival after diagnosis for early breast cancer. We measured glycated hemoglobin in a group of cancer patients (some with active disease and some in remission) and found a statistically significant lower average blood glucose in those in remission. Glycated hemoglobin provides an indication of average blood glucose over 2 to 3 months. The authors discuss lifestyle changes including diet and physical activity that can reduce average blood glucose. Ascorbic acid (AA) supplementation as an adjunct to cancer therapy is also considered. Furthermore, they present a biologically plausible explanation for how hyperglycemia can impair the actions of AA and damage immune effectiveness and hinder cancer survival. One mechanism is likely a reduction in intracellular AA; high intracellular levels of AA are necessary for optimal activity of the hexose monophosphate shunt. This metabolic pathway is important for maintaining proper cellular antioxidant status in immune cells including lymphocytes involved in cell-mediated immunity.