Antioxidants and cancer therapy: a systematic review.
OBJECTIVE
Many patients with cancer take antioxidant nutritional supplements during cancer treatment to alleviate treatment toxicities and to improve long-term outcomes, but little is known about the efficacy and safety of antioxidant use during cancer treatment. We reviewed English-language manuscripts published in the biomedical literature, reporting the results of observational studies of antioxidant status and cancer outcomes and of intervention trials of antioxidants among patients receiving chemotherapy with or without radiation for various malignancies.


METHODS
We searched the Medline database and the bibliographies of the retrieved manuscripts, reviews, and books on antioxidants and cancer. The retrieved studies are grouped by study design, malignancy, and end points.


RESULTS
More than 100 citations were retrieved; 52 met our criteria, 31 were observational studies, and 21 were intervention trials. The studies varied in study design, timing of observation/intervention, intervention protocol, malignancy, and anticancer regimen.


CONCLUSIONS
These inconsistencies preclude a definitive conclusion as to the effect of chemotherapy on antioxidant status in patients undergoing anticancer therapy. However, our review suggests that total antioxidant status (measured by total radical antioxidant parameter) declines during cancer treatment. Adequately powered trials or observational studies among patients with a specific cancer diagnosis receiving a specific treatment regimen are needed to address patients' and physicians' concerns regarding these associations.
Ladas
Elena J
EJ
Division of Pediatric Oncology, Children's Hospital of New York, New York, NY, USA.
Jacobson
Judith S
JS
Kennedy
Deborah D
DD
Teel
Katherine
K
Fleischauer
Aaron
A
Kelly
Kara M
KM
D000975:Antioxidants / Q000627:therapeutic use*; D017024:Chemotherapy, Adjuvant; D002986:Clinical Trials as Topic; D019587:Dietary Supplements; D006801:Humans; D009369:Neoplasms / Q000188:drug therapy*; D018714:Radiotherapy, Adjuvant; D014815:Vitamins / Q000627:therapeutic use
D000975:Antioxidants; D014815:Vitamins