Gesellschaft für angewandte Vitaminforschung (GVF)

GVF-Stellungnahme zu Antioxidantien und Krebs (engl.)

A Randomized Trial of Antioxidant Vitamins to Prevent Second Primary Cancers in Head and Neck Cancer Patients vom (Mai 2005)
Isabelle Bairati et al.
J. Nat. Cancer Inst. 97, 481-88, 2005

Objective
Primary objective: to assess whether the intervention would reduce the incidence of second primary cancers.
Second objective: to assess whether the intervention would reduce the adverse effects of radiation therapy without compromising treatment efficacy.
Third objective: to assess whether the intervention would improve cancer-free survival.

Methodology

Multicenter, double-blind, placebo-controlled, randomized chemoprevention trial among 540 patients with stage I or II head and neck cancer treated by radiation therapy between 1994 and 2000. Supplementation: alpha-tocopherol (400 IU/day) and beta-carotene (30 mg/day); began on the first day of radiation therapy and continued for 3 years after the end of radiation therapy. Beta-carotene supplementation was discontinued after 156 patients had enrolled because of ethical concerns. The remaining patients received alpha-tocopherol or placebo only. Survival was evaluated by Kaplan-Meier analysis. Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs).

Results

After a median follow-up of 52 months, second primary cancers and recurrences of the first tumor were diagnosed in 113 and 119 participants, respectively. The effect of supplementation on the incidence of second primary cancers varied over time. Compared with patients receiving placebo, patients receiving alpha-tocopherol supplements had a higher rate of second primary cancers during the supplementation period (HR = 2.88, 95% CI = 1.56 to 5.31) but a lower rate after supplementation was discontinued (HR = 0.41, 95% CI = 0.16 to 1.03). Similarly, the rate of having a recurrence or second primary cancer was higher during (HR = 1.86, 95% CI = 1.27 to 2.72) but lower after (HR = 0.71, 95% CI = 0.33 to 1.53) supplementation with alpha-tocopherol. Overall, after eight years, the proportion of patients who were free of a second primary cancer was similar in both groups.

Conclusions

Unexpectedly, patients who received vitamin E supplements were at greater risk of developing a second primary cancer while receiving supplementation, as well as a lower risk of a second primary cancer after the end of supplementation (compared with placebo patients).