Article

Should Supplemental Antioxidant Administration Be Avoided During Chemotherapy and Radiation Therapy?

Radiation Oncology Division, Breast Health Center, Naval Medical Center San Diego, San Diego, CA, USA.
Journal of the National Cancer Institute (Impact Factor: 12.58). 07/2008; 100(11):773-83. DOI: 10.1093/jnci/djn148
Source: PubMed

ABSTRACT

Despite nearly two decades of research investigating the use of dietary antioxidant supplementation during conventional chemotherapy and radiation therapy, controversy remains about the efficacy and safety of this complementary treatment. Several randomized clinical trials have demonstrated that the concurrent administration of antioxidants with chemotherapy or radiation therapy reduces treatment-related side effects. Some data indicate that antioxidants may protect tumor cells as well as healthy cells from oxidative damage generated by radiation therapy and some chemotherapeutic agents. However, other data suggest that antioxidants can protect normal tissues from chemotherapy- or radiation-induced damage without decreasing tumor control. We review some of the data regarding the putative benefits and potential risks of antioxidant supplementation concurrent with cytotoxic therapy. On the basis of our review of the published randomized clinical trials, we conclude that the use of supplemental antioxidants during chemotherapy and radiation therapy should be discouraged because of the possibility of tumor protection and reduced survival.

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    • "ALDH activity can be inhibited pharmacologically by 4-diethylaminobenzaldehyde (DEAB) (Fig. 1). Because chemotherapy is known to induce oxidative stress [44], it is possible that inhibition of ALDH activity using DEAB may sensitize ALDH hi CSC to therapy through enhanced exposure to ROS and induction of apoptosis [41]. We were able to increase susceptibility of colorectal cancer cells (HT-29) to chemotherapy after incubation with DEAB in our preliminary study. "
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    ABSTRACT: Malignant tumours consist of heterogeneous populations of tumour cells. Cancer stem cells (CSC) represent a population of cells within a tumour with highly tumorigenic and chemoresistant properties. These cells may be identified by the expression of CSC markers. There are several key stem cells markers specified for colon cancer: CD133, CD44, ALDH1, ALCAM. These days, a major obstacle to effective cancer management is development of a multidrug resistance (MDR). The principal mechanism responsible for development of MDR phenotype is the over-expression of ABC transporters. Tumours and relapsing tumours after therapy are drived by subpopulations of tumour cells with aggressive phenotype resistant to chemotherapeutics. These cells are called CSC or tumour-initiating cells (TIC). Here we outline recent information about MDR of colon cancer and CSC markers. We have focused on novel therapeutic strategies which have been developed to prevent or overcome MDR. One such strategy is a combination of chemotherapy and modulators of MDR pumps or chemotherapy and monoclonal antibodies against vascular endothelial growth factor VEGF. Colon cancer is characterized by the presence of colon CSC expressing specific stem cell markers. The divergent presence of these markers can help to adjust personalized therapy. The review provides a detailed overview of resistance of colon cancer cells and discusses how the presence of CSC markers can influence therapy and prognosis of patients.
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    • "Thereby, in some preclinical studies led in-vitro and in-vivo, ascorbic acid induced tumor cells apoptosis and even enhanced the anti-tumor effects of chemotherapy [6] [7], acting then as a potentially good therapeutic adjuvant. Conversely, evidence from other studies and randomized trials[8] suggested that ascorbic acid during chemotherapy or radiation therapy may protect tumor cells and reduce the treatment efficacy. "

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    • "With regard to sulforaphane, its modus operandi is believed to be as an indirect antioxidant that helps to protect healthy cells from oxidative damage and reduce the short- and long-term harmful effects of cancer treatment [42]. However, concern has been raised that antioxidant supplements may also protect tumor cells during chemotherapy, thereby compromising treatment efficacy [42,43]. "
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