Hormonal contraceptives meta-analysis

A meta-analysis of epidemiological studies of ovarian cancer showed a summary estimated relative risk of 0.64 for ever-use of combined oral contraceptives, implying a 36% reduction in ovarian cancer risk (130). This protective effect increased with increasing duration of oral contraceptive use and continued for at least 10 years after discontinuation. Although most of the oral contraceptives reported in these studies were older, higher-dose formulations, the Cancer and Steroid Hormone (CASH) study included users of tablets containing ethinylestradiol 35 pg or less, and this subgroup of women had a reduced risk of ovarian cancer (115). 

Rosa MI, Madeira K, Medeiros LR. Can a meta-analysis that included articles with high heterogeneity appropriately evaluate the risk of venous thromboembolism in users of combined hormonal contraceptives containing drospirenone or desogestrel Eur J Contracept Reprod Health Care 2013 18(2) 137-9. 

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