Risk of endometrial, ovarian and breast cancer in women with polycystic ovary syndrome: A systematic review and meta-analysis

Abstract

Background: Polycystic ovary syndrome (PCOS) is a common condition affecting ~8% of women. The objective of the present study was to quantify separately the risk of endometrial cancer, ovarian cancer and breast cancer in women with PCOS compared with non-PCOS controls, and quantify separately the risk to women of all ages as well as the risk to premenopausal women. Methods: We conducted a systematic review and meta-analysis of observational studies. Studies were eligible for inclusion if they compared women with PCOS to non-PCOS groups for fatal or non-fatal gynaecological cancers. Studies listed in MEDLINE and EMBASE published up to 7 October 2013 in any languagewere identified, and relevant papers were also searched by hand. Relevant data (for example, study design, source of control data, diagnostic criteria) were extracted and tabulated. Results: From698 references, 11 studies (5of endometrial cancer and 3 each of ovarian andbreast cancer) met the inclusion criteria for themetaanalysis (919 women with PCOS and 72054 non-PCOS controls). Using the Mantel-Haenszel method, with fixed or random effects model as appropriate, women with PCOS were at a significantly increased risk of endometrial cancer (odds ratio (OR), 2.79; 95% confidence interval (CI), 1.31-5.95, P < 0.008), but the risk of ovarian and breast cancers was not significantly increased (OR, 1.41; 95% CI, 0.93-2.15, P < 0.11 and OR, 0.95; 95% CI, 0.64-1.39, P < 0.78, respectively).Howeverwhen studies which includedwomen aged over 54 yearswere excluded fromthe analysis, the risk forwomenwith PCOS increased further for endometrial cancer (OR, 4.05; 95% CI, 2.42-6.76, P < 0.00001), became significantly increased for ovarian cancer (OR, 2.52; 95% CI, 1.08-5.89, P < 0.03), but remained non-significant for breast cancer (OR, 0.78; 95% CI, 0.46-1.32, P < 0.35). Conclusions: This is the firstmeta-analysis to examine gynaecological cancers in women with PCOS younger than 54 years of age compared with controls of similar age.Current data suggest thatwomen of all ageswith PCOS are at an increased riskof endometrial cancer but the riskofovarian and breast cancerwas not significantly increased overall. These results highlight the potential risk of gynaecological cancer morbidities associatedwith PCOS.However, the available evidence is far fromrobust and variationin diagnostic criteria forPCOS, associated risk factors (particularly obesity), and selection bias in the studies may have resulted in an exaggeration of the increased risk. Furthermore, women who have PCOS should also be made aware that any increased risk for endometrial cancermust be judged in the context of its relatively lowincidence in the general population.Alargewellcontrolled prospective study is required in order to gain a more accurate estimate of the risk of gynaecological cancers in women with PCOS. © The Author 2014. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved.