Should Patients Undergoing Chemotherapy and Radiotherapy Be Prescribed Antioxidants?

Abstract

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.

Effects of genistein following fractionated lung irradiation in mice

“…There is considerable debate as to whether to give antioxidants during radiotherapy [184][185][186][187][188][189][190]. There is concern that increasing the antioxidant capacity of cells, particularly tumor cells would lessen the effect of radiation that kills tumor cells via oxidative damage.…”

Effect of ursodeoxycholic acid and vitamin E in the prevention of liver injury from methotrexate in pediatric leukemia

“…Nevertheless, little is known regarding the effectiveness and safety of antioxidant use during chemotherapy (17). There is a major concern regarding the possible interaction of antioxidants with chemotherapy agents (18).…”

Ascorbic acid modulates doxorubicin and cyclophosphamide-induced cytogenetic damages in Sarcoma 180 cells

“…There are reports on the effect of antioxidants such as ascorbic acid, tocopherol and carotenoid that can inhibit the effects of various cytostatic drugs (5-fluorouracil, doxorubicin and vincristine) through cultures and cell lines [51,52], which may reduce toxic effects in cellular systems [53].…”