Reply #6: Then there's this... but you can't trust them people "over there". [View All]

[HysteryDiagnosis]

http://www.jacn.org/cgi/content/full/24/1/16


In another study, thirty-two ‘high risk’ breast cancer patients, aged 32–81 years, were given adjuvant nutritional intervention (a combination of Vitamins C, E, beta-carotene, Selenium, essential fatty acids and Coenzyme Q10) and followed for 18 months <25>. None of the patients died during the study period or showed signs of distant metastases. The quality of life of these patients was improved and six patients showed apparent partial remission. Antioxidant supplementation (beta-carotene 45 mg, alpha-tocopherol 825 mg and ascorbic acid 450 mg daily for three weeks) before conditioning therapy in bone marrow transplant patients led to no difference in relapse rates <26>. In another study with 65 patients of bladder carcinoma treated with BCG immunotherapy, supplementation with mega-dose combination of vitamin A (40,000 units), vitamin B6 (100 mg), vitamin C (2000 mg), vitamin E (400 units) and Zinc (90 mg) led to decreased recurrence rates at 10 months of follow up (40% vs. 80%) compared to patients receiving RDA values of these agents <27>. These variations in clinical studies may be due to differences in doses, type and number of antioxidants. Therefore, it is essential to define the optimal number, type and dose of antioxidants for a maximal benefit when used as an adjunct to standard therapy.

Pre-clinical data showed that antioxidant vitamins reduce the frequency and severity of toxicity associated with (x)-irradiation and chemotherapeutic agents. For instance, vitamin E has been shown to decrease adriamycin-induced toxicity in rabbits <28>; vitamin E in combination with pentoxifyllin has been reported to significantly regress the radiation-induced fibrosis <29>. In the current study, however, no such protection was seen when we used paclitaxel and carboplatin. It would thus appear that the protective effect of antioxidants on normal cells might not be against all anticancer agents.

There are certain limitations in the present study that should be considered while interpreting the findings. The antioxidants (beta carotene, vitamin E and vitamin C) could not be used in their biologically active forms due to constraints of commercial availability. For example, the 9-cis isomer of beta-carotene found in natural preparations may be a more potent antioxidant <30> compared to the all-trans isomer used by us. Similarly, d-{alpha}-tocopherol succinate is considered more active form than the synthetic form (dl)-alpha-tocopherol succinate used by us <31>. Thus, there is a possibility that the results might improve if more active forms of antioxidant vitamins are used. Also, the antioxidant preparation used by us contained other compounds like copper sulfate, manganese sulfate, zinc sulfate and selenium, which might have affected the results. For instance, selenium has its own antioxidant properties, which might have confounded the results <32>. Another limitation of the present study is that the serum levels of the antioxidants were not estimated. In order to establish an optimal dose response relationship, it is essential that future studies utilizing antioxidant preparations be based on pharmacokinetic data.

Large-scale phase III clinical trials in relatively homogeneous patient populations receiving well-specified conventional treatment regimen alone and in combination with high-dose multiple antioxidants are needed to clarify the true potential of antioxidants in the management of human malignancies.


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In conclusion, antioxidant supplementation during paclitaxel/carboplatin containing chemotherapy in NSCLC appears to be safe and the results of the present study do not support the hypothesis that antioxidant vitamins could compromise the efficacy of standard chemotherapy. There is a possibility that these agents could be potentially useful in the management of NSCLC. Larger controlled trials are required to ascertain their exact role.