Current Attitudes and New Approaches to Treatment Cancer therapy has been remarkably consistent for the last 50 years. Surgery, radiation, and chemotherapy have been the cornerstones of conventional treatment. Not surprisingly, the clinical success of these treatments has reached a plateau.176 Some authors have even questioned the validity of chemotherapy as a treatment for most cancers.177 Clearly, there is a need for new therapies which can increase the efficacy of cancer treatment. Careful application of antioxidants may be a means helping to raise cancer therapy to a new level of success.4 The attitude of many conventional practitioners toward antioxidant therapy for cancer has been hostile.178 Others have raised the argument that antioxidants could blunt the effect of standard therapies, particularly alkylating, platinum, and tumor antibiotic agents, which are oxidative in nature.5 While this appears a theoretical concern, the evidence reviewed here shows that this proposed interaction of anti- and pro-oxidant therapies is not generally of primary importance in vivo. It is time to put this argument in perspective. Potential Mechanisms of Antioxidants in Cancer Therapy How could antioxidant therapy protect normal cells against damage from cancer therapies, while often increasing their cytotoxic effect against malignant cells? While the answer to this question is not entirely mapped out, there are concepts which might help us understand. One is the recent evidence that radiation and chemotherapy often harm DNA to a relatively minor extent, which causes the cells to undergo apoptosis, rather than necrosis.6 Since many antioxidant treatments stimulate apoptotic pathways,7,8 the potential exists for a synergistic effect with radiation or chemotherapy with antioxidants. A second concept is that the defensive mechanisms of many cancer cells are known to be impaired. This presumably makes tumor cells unable to use the extra antioxidants in a repair capacity; this has been illustrated in vitro. An experimental murine ascites tumor cell line was found to have 10 -100 times less catalase than comparable normal cells. This led to a build-up of hydrogen peroxide in the cells upon treatment with vitamin C, in turn leading to cell death. The cytotoxic effects of vitamin C were completely eliminated by addition of catalase to the cell culture.179 Since publication of these findings, most human tumor cell lines studied have proved to be similarly low in catalase.180 Caveats When Considering Using Antioxidants in Cancer Treatment We wish to emphasize three concerns regarding the use of antioxidants raised in this paper. One is the routine use of N-acetylcysteine with certain chemotherapeutic agents, namely cisplatinum and doxorubicin. Given the limited therapeutic benefits associated with NAC in cancer treatment, and the number of other antioxidants shown above to help reduce the toxicities of these two chemotherapeutic agents, there appears little reason to consider NAC a first-line adjunct with either agent. Since the potential for adverse interaction with chemotherapy appears to be greater with NAC, perhaps it should be used only in situations where it has clearly been shown to not interfere with other therapies. The second concern we wish to reiterate is the interaction between tangeretin and tamoxifen. Except in cases where interactions with specific flavonoids are clearly defined, it seems prudent to avoid treatment with flavonoids in therapeutic doses concurrently with tamoxifen. It is unknown currently if there is any reduction in tamoxifen activity associated with dietary flavonoids, which are ubiquitous in the plant kingdom. The third area of concern is the potential reduction of 5-fluorouracil (5-FU) activity by beta-carotene.58 The nature of this interaction is not clear. Until this is clarified, the combination would best be avoided. Alternative Medicine Reviews, 1999;4(5):304-329 Remember we are NOT Doctors and have NO medical training. This site is like an Encylopedia - there are many pages, many links on many topics. Support our work with any size DONATION - see left side of any page - for how to donate. You can help raise awareness of CAM.