Sex Hormones、Reproductive Factors And Esophageal Cancer Risk:a Meta-Analysis

BackgroundOesophageal carcinoma is one of the most common malignant cancers. Incidence and mortality rate is top of the world. It was482,000new oesophageal cancers estimated in2008. And the morbidity and mortality rates of esophageal cancer in male were higher than that of the female, and ratio of male to female was increased with ages. The study shows that the increase of level of endogenous estrogen exposure can reduce the risk of esophageal cancer, however, conclusions were diverged depending upon countries, regions and ethnic groups studied. And the research about different gender cause the obvious differences in incidence of esophageal cancer risk factors are not consistent. This article uses meta-analysis to evaluate the research results of relations of sex hormones, reproductive factors and risk of esophageal cancer in order to describe this correlation accurately.ObjectiveThe purpose of present study is using meta-analysis to summarize the relative results which is about the relationship between sex hormones、reproductive factors and risk of oesophageal cancer.MethodsThrough search Pubmed, Medline, CNKI, SpringLINK and WANFANG database, with other retrieval methods to identify literature publish up to December31,2013without language restriction,than related to both the expose (sex hormones、reproductive factors) and outcome (oesophageal cancer) of interest. Two investigators independently reviewed titles and abstracts of all identified citations.Two investigators independently according to the inclusion and exclusion standard of all identified citations and complete the data extraction.Weighted mean difference (WMD) were estimated and pooled using meta-analysis methods.We assumed that the variability of the results depends on the variability of intra-and inter-studies, that a fixed or random-effects was used. The data from references was analysised by Stata11.0software.Results1. A total of11studies up to december31,2013were included,9of which are case-control study and3of which are cohort study.The cases include2453patients and controls include14145.All are ended by odds ratio.2. According to meta analysis:later age at menopause>50y (OR=0.620,95%CI:0.463-0.829),age at first birth23-26y (OR=0.621,95%CI:0.715-0.997),use hormone therapy(OR=0.742,95%CI:0.624-0.883)and parity(OR=0.765,95%CI:0.628-0.933) were significantly associated with esophageal cancer risk.Age at menarche and the number of parity were not significantly associated.3. According to funnel graphics,this study inexistence published bias,but have no substantial influence on the results.Conclusions1. Sex hormones and reproductive factors closely related to the risk of esophageal cancer.2. The protective factors influencing the incidence of esophageal cancer are Later age at menopause(>50y),age at first birth (23-26y) and use hormone therapy.The risk factors are less than age at menopause(≤50y) and none of parity.But the relationships are still unclear between age at menarche.