Dual effects of vitamin C supplementation combined with chemotherapy in breast cancer patients

Introduction and Aim: Chemotherapy-related toxicity is a major concern inthe treatment of breast cancer patients. Formation of free radicals bychemotherapy drugs, leading to oxidative stress, has been shown to be one ofthe main pathogenetic mechanisms of these toxicities and side-effects of thesedrugs, such as cardiomyopathy and pulmonary damage. As reduced plasmalevel of antioxidants such as vitamin C reported during chemotherapy could beresponsible for such problems, the aim of this article is surveying the effects ofvitamin C supplementation in breast cancer patients.Methods and Materials: This article is a review on articles published ingooglescolar and pubmed since 2000.Results: based on evidences from primary clinical trials, supplementation with10g/day vitamin C during chemotherapy had not any beneficial effect onresponse to therapy and survival time. Recent trials clarified supplementationwith high dose vitamin C had no significant effects on chemotherapy outcomesand decreases its efficacy. Results from in vitro studies are very conflicting.Some studies suggested treatment of tumor cells with vitamin C and K3appeared synergistic action combined with chemotherapy, stimulatedcytotoxicity and sensitized the drugs whereas pretreatment with vitamin Ccombined with K3, vitamin C or K3 alone had not any effect. While in MCF-7and MDA-MB-231 breast cancer cell lines 102 – 103 μM vitamin C stronglyincrease sensitivity to chemotherapy drugs.Conclusion: Although vitamin C as an antioxidant can prevent a breastcarcinogenesis, but during chemotherapy due to decreasing the sensitivity tochemotherapy drugs by interfere with formation of free radicals, may haddecrease efficacy of chemotherapy. Thus supplementation with a higher dose ofvitamin C and in combination with other antioxidants in breast cancerchemotherapy should be investigated further.

کلیدواژه ها:

chemotherapy ، vitamin C ، breast cance