Vitamin A and risk of cervical cancer: a meta-analysis

Objective: To conduct a systematic review with meta-analysis of studies assessing the association of vitamin A (retinol, carotene and other carotenoids) intake or blood (serum or plasma) levels of vitamin A (retinol and carotene) with risk of cervical cancer.

Methods: We evaluated the studies published in English and Chinese on diet or blood vitamin A for the risk of cervical cancer. We also reviewed reference lists from retrieved articles. Meta-analysis was applied to calculate the combined effect values and their 95% confidence intervals. The risk of bias was assessed by the Egger regression asymmetry test.

Results: As many as 11 articles on dietary vitamin A and 4 articles on blood vitamin A were selected according to the eligibility criteria and were included in the meta-analysis, for a total of 12,136 participants. The pooled odds ratios (ORs) of cervical cancer were 0.59 (95% CI, 0.49-0.72) for total vitamin A intake and 0.60 (95% CI, 0.41-0.89) for blood vitamin A levels. The combined ORs of cervical cancer were 0.80 (95% CI, 0.64-1.00), 0.51 (95% CI, 0.35-0.73) and 0.60 (95% CI, 0.43-0.84) for retinol, carotene and other carotenoid intake, and 1.14 (95% CI, 0.83-1.56) and 0.48 (95% CI, 0.30-0.77) for blood retinol and carotene.

Conclusions: Vitamin A intake and blood vitamin A levels were inversely associated with the risk of cervical cancer in this meta-analysis.