Abstract
Several epidemiological studies have suggested that vitamin E could reduce the risk of uterine cervical neoplasm. However, controversial data were presented by different reports. Hence, we conducted a meta-analysis to assess the relationship between vitamin E and the risk of cervical neoplasia. We performed a comprehensive search of the PubMed, Embase and Cochrane databases through December 31, 2016. Based on a fixed-effects or random-effects model, the odds ratio (OR) and 95% confidence intervals (CIs) were calculated to assess the combined risk. Subgroup analyses and meta-regression were done to assess the source of heterogeneity. Subgroup analyses were performed according to survey ways, types of cervical neoplasia, study populations. A protocol was registered with PROSPERO (No. CRD42016036672). In total, 15 case-control studies were included, involving 3741 cases and 6328 controls. Our study suggested that higher category of vitamin E could reduce the cervical neoplasia risk (OR = 0.58, 95% CIs = 0.47–0.72, I2 = 83%). In subgroup-analysis, both vitamin E intake and blood levels of vitamin E had a significant inverse association with the risk of cervical neoplasm. Additionally, we found the same relationship between vitamin E and cervical neoplasia among different populations and types of cervical neoplasia. Meta-regression showed that none of the including covariates were significantly related to the outcomes. No evidence of publication bias was observed. In conclusion, vitamin E intake and blood vitamin E levels were inversely associated with the risk of cervical neoplasia.
Highlights
Cervical cancer remains the third most common gynecological malignancy in the world and the leading cause of mortality among women in developing countries [1], and responsible for an estimated 265,000 deaths annually worldwide, 87% occurring in low-resource countries [2]
Vitamin E and cervical neoplasm play an important role in the prevention of cervical carcinoma [5], and many studies have shown that dietary vitamin E might reduce the risk of cervical dysplasia and cancer [6,7]
Our meta-analysis indicated that there was a significant negative relationship between vitamin E and the risk of cervical neoplasia
Summary
Cervical cancer remains the third most common gynecological malignancy in the world and the leading cause of mortality among women in developing countries [1], and responsible for an estimated 265,000 deaths annually worldwide, 87% occurring in low-resource countries [2]. Overwhelming evidence supports the role of human papillomaviruses (HPV) in cervical carcinogenesis [3,4]. Vitamin E and cervical neoplasm play an important role in the prevention of cervical carcinoma [5], and many studies have shown that dietary vitamin E might reduce the risk of cervical dysplasia and cancer [6,7]. Vitamin E, which contains putative anticancer and antimutagenic substances, had long been thought to protect against cancer, including cervical cancer. Vitamin E is a well-known inhibitor of lipid peroxidation and a powerful antioxidant, which has been reported to protect cells from oxidative DNA damage and mutagenesis, thereby preventing the occurrence of some tumors [8,9]
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