Hormone replacement therapy and oral contraceptives and risk of oesophageal adenocarcinoma: a systematic review and meta-analysis.

There is an unexplained strong male predominance in the aetiology of oesophageal adenocarcinoma (OAC). The hypothesis that oestrogens are protective, deserves attention. A potential protective influence of exogenous oestrogen exposure, that is, hormone replacement therapy (HRT) and oral contraceptives (OC) has been addressed only in studies of limited statistical power, and the individual studies have not provided conclusive results. We conducted a systematic literature search and meta-analysis on HRT and OC and the risk of OAC. We used the databases PubMed and the Web of Science. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated by the Mantel-Haenszel random-effect method. A total of five studies were included. Compared to never users, ever users of HRT had a statistically significantly decreased risk of OAC (pooled OR = 0.75; 95% CI: 0.58-0.98), and ever users of OC had a borderline significantly decreased risk of this cancer (pooled OR = 0.76; 95% CI: 0.57-1.00). In conclusion, HRT and OC use seems to be associated with a decreased risk of OAC. However, further research is warranted.