Antioxidants in cancer care: when and how to use them as an adjunct to standard and experimental therapies.
Cancer patients can be divided into two groups: those receiving therapy and those in remission carrying the risk of a second new cancer. Surgery, radiation therapy and chemotherapy are used for the treatment of the first group of patients; however, at present, there is no strategy to reduce the risk of a new cancer in the second group. While impressive progress in radiation therapy and chemotherapy has been made, the value of these modalities in tumor control may have reached a plateau. Therefore, additional approaches are needed to improve the efficacy of current cancer management. An active nutritional protocol that includes high doses of multiple dietary antioxidants and their derivatives, but not endogenously made antioxidants, as an adjunct to standard therapy is proposed, which may improve efficacy by increasing tumor response and decreasing toxicity. This protocol is in clinical trial. In addition, after completion of standard therapy, adopting a maintenance nutritional protocol that contains lower doses of antioxidants and their derivatives, together with modification in diet and lifestyle, may reduce the risk of recurrence of the original tumor and development of a second cancer. The efficacy of this protocol remains to be tested. In contrast, most oncologists do not recommend antioxidants during therapy, fearing that they may protect cancer cells against the damaging effect of treatment agents. These opposite recommendations are due to the fact that the results obtained from one experimental condition are extrapolated to another and no distinction between the effect of dietary and endogenously made antioxidants, or between doses, dose schedule, treatment period, form and number of antioxidants is made. This review discusses these issues and provides a biological and clinical rationale for the use of active and maintenance nutritional protocols as an adjunct to standard therapy and after therapy, respectively.
Prasad
Kedar N
KN
Center for Vitamin and Cancer Research, Department of Radiology, University of Colorado, Health Sciences Center, Denver 80262-80278, USA. KedarPrasad@UCHSC.edu
D000277:Adjuvants, Pharmaceutic / Q000627:therapeutic use*; D000818:Animals; D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D000975:Antioxidants / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D045744:Cell Line, Tumor / Q000187:drug effects; D006801:Humans; D009369:Neoplasms / Q000178:diet therapy / Q000188:drug therapy*; D035703:Therapies, Investigational / Q000379:methods*
D000277:Adjuvants, Pharmaceutic; D000970:Antineoplastic Agents; D000975:Antioxidants