A systematic review and meta-analysis found contradictory evidence, casting doubt on antioxidant vitamin supplement (AVS) use after receiving a breast cancer diagnosis. These findings were published in Clinical Breast Cancer.
Survivors of breast cancer report a higher prevalence of dietary supplementation use compared with other cancers. Emerging reports have linked dietary supplements with decreased survival; however, it remains unclear whether these detrimental effects are caused by AVSs or other products.
Publication databases were searched through October 2020 for studies of AVS use in the breast cancer setting. This analysis included 8 studies published between 2011 and 2019, comprising 17,062 patients.
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For overall survival, there was a trend that favored AVS use (hazard ratio [HR], 0.92; 95% CI, 0.82-1.03; P =.16; I2, 36%). However, when studies were stratified by publication date, earlier studies tended to favor AVSs (HR, 0.85; 95% CI, 0.72-1.00; P =.06; I2, 0%) and later studies tended not to (HR, 1.23; 95% CI, 0.96-1.58; P =.10; I2, 0%).
For breast cancer-specific survival, no significant effect was observed overall (HR, 1.00; 95% CI, 0.75-1.32; P =1.00; I2, 66%). The earlier studies significantly favored use of AVSs (HR, 0.86; 95% CI, 0.74-1.00; P =.05; I2, 0%) and the later study non-use of AVSs (HR, 1.64; 95% CI, 1.07-2.51; P =.02).
Stratified by supplement, evidence supported vitamin C use (HR, 0.84; 95% CI, 0.76-0.93; P =.001; I2, 0%) but not vitamins A or E.
This study was limited by the few studies and significant heterogeneity observed.
These data call into question the use of AVS in the breast cancer setting. Additional study is needed to improve understanding of the effect of vitamin supplementation on breast cancer survival and outcomes.
Reference
Li Y, Lin Q, Lu X, Li W. Post-diagnosis use of antioxidant vitamin supplements and breast cancer prognosis: a systematic review and meta-analysis. Clin Breast Cancer. 2021;21(6):477-485. doi:10.1016/j.clbc.2021.09.001
