Vitamin A and Breast Cancer Survival: A Systematic Review and Meta-analysis.

BACKGROUND: The association between vitamin A intake and breast cancer survival has been inconsistent. We conducted a systemic review and meta-analysis to summarize the results on the association between dietary or supplement vitamin A and its derivatives and breast cancer-specific survival and overall survival (OS). MATERIALS AND METHODS: A comprehensive search of PubMed and EMBASE was performed from inception to January 31, 2018. The summary hazard ratios and 95% confidence intervals were estimated using a random effects model.

RESULTS: Ten studies (8 cohort, 1 clinical trial, and 1 of pooled studies), with 19,450 breast cancer cases, were included in the meta-analysis. The dietary intake of β-carotene was significantly associated with improved breast cancer OS, with a summary hazard ratio of 0.70 (95% confidence interval, 0.50-0.99; I2  = 37.5%) for the highest versus lowest intake and 0.93 (95% confidence interval, 0.88-0.99; I2  = 38.7%) per 1200 μg/day increment of intake when assessing diet before diagnosis. Meta-regression analysis showed that adjustment for body mass index was a modified factor for the association between the intake of β-carotene and breast cancer OS (P = .013). However, the intake of other vitamin A derivatives (eg, α-carotene, β-cryptoxanthin, lycopene, retinol, lutein) had no effect on breast cancer prognosis when assessing diet before and after the diagnosis.

CONCLUSION: Our findings suggest limited evidence for the significantly inverse association between the prediagnosis dietary intake of β-carotene and OS among women with breast cancer. However, the intake of other vitamin A derivatives was not significantly associated with survival.