Incidence of skin cancers during 5-year follow-up after stopping antioxidant vitamins and mineral supplementation.

CONTEXT

In the SU.VI.MAX study, antioxidant supplementation for 7.5 years was found to increase skin cancer risk in women but not in men.

OBJECTIVE

To investigate the potential residual or delayed effect of antioxidant supplementation on skin cancer incidence after a 5-year post-intervention follow-up.

DESIGN, SETTING AND PARTICIPANTS: Assessment of skin cancer including melanoma and non-melanoma during the post-intervention follow-up (September 2002-August 2007). The SU.VI.MAX study was a double-blind, placebo-controlled, randomised trial, in which 12,741 French adults (7713 women aged 35-60 years and 5028 men aged 45-60 years) received daily a placebo or a combination of ascorbic acid (120 mg), vitamin E (30 mg), β-carotene (6 mg), selenium (100 μg) and zinc (20mg), from inclusion in 1994 to September 2002.

MAIN OUTCOME MEASURES

Total skin cancer incidence, including melanoma, squamous cell carcinoma and basal cell carcinoma.

RESULTS

During the post-intervention period, 10 melanomas appeared in women and 9 in men (26 and 18, respectively, for the total period of supplementation+post-supplementation). Six squamous cell carcinomas were found in women and 15 in men (10 and 25, respectively, for the total period). Finally, 40 basal cell carcinomas appeared in women and 36 in men (98 and 94, respectively, for the total period). Regarding potential residual or delayed effects of supplementation in women, no increased risk of melanoma was observed during the post-intervention follow-up period. No delayed effects, either on melanoma or non-melanoma skin cancers, were observed for either gender.

CONCLUSIONS

The risk of skin cancers associated with antioxidant intake declines following interruption of supplementation. This supports a causative role for antioxidants in the evolution of skin cancers.