Barry, J. A., Azizia, M. M., & Hardiman, P. J. (2014). Risk of endometrial, ovarian and breast cancer in women with polycystic ovary syndrome: a systematic review and meta-analysis. Human reproduction update. https://doi.org/10.1093/humupd/dmu012
Barry JA, Azizia MM, Hardiman PJ. Risk of endometrial, ovarian and breast cancer in women with polycystic ovary syndrome: a systematic review and meta-analysis. Human reproduction update. 2014. doi:10.1093/humupd/dmu012
Barry, J. A., et al. "Risk of endometrial, ovarian and breast cancer in women with polycystic ovary syndrome: a systematic review and meta-analysis." Human reproduction update, 2014.
Women With PCOS Show Higher Odds of Endometrial Cancer
Women with PCOS had 2.79 times the odds of endometrial cancer. This 2014 meta-analysis combined 11 observational studies. They covered 919 women with PCOS (also called PMOS, Polyendocrine Metabolic Ovarian Syndrome) and 72,054 controls. Endometrial odds were higher still in the four studies of women under 54. Breast cancer odds showed no significant difference.
Study at a glance, meta-analysis of 919 women with PCOS: Women with PCOS had higher odds of endometrial cancer. Source: Barry JA et al., 2014, PMID 24688118.
Key Findings
The 11 studies covered endometrial cancer (5 studies), ovarian cancer (3) and breast cancer (3), comparing 919 women with polycystic ovary syndrome (PCOS) against 72,054 controls without PCOS.
Endometrial cancer: odds ratio (OR) 2.79 (95% CI 1.31–5.95) across all five studies. Excluding the study that included women over 54, the OR was 4.05 (95% CI 2.42–6.76).
Ovarian cancer: OR 1.41 (95% CI 0.93–2.15) across three studies, a result that was not significant. The one study limited to women under 54 gave an OR of 2.52 (95% CI 1.08–5.89).
Breast cancer: OR 0.95 (95% CI 0.64–1.39) across three studies, and 0.78 (95% CI 0.46–1.32) in the two studies of younger women. Neither result was significant.
Interpretation
The paper is a systematic review and meta-analysis of observational studies, most of them case–control studies. An odds ratio above 1 means higher odds of cancer in women with PCOS than in controls. The endometrial cancer association appeared in all five studies. The endometrial odds ratio rose from 2.79 to 4.05 when the one study that included women over 54 was excluded. The authors describe the evidence as far from robust. They say varied PCOS criteria, obesity and selection bias may have exaggerated the increased risk. The authors add that the low incidence of endometrial cancer in the general population puts any increased risk in perspective.
RRM Context
Restorative reproductive medicine looks for causes and uses cycle charting. Missing or irregular ovulation in PCOS is a finding to explain. The authors name long stretches without ovulation, plus unopposed estrogen, as possible ways PCOS could raise cancer risk. Ovulation matters for long-term health in PCOS, along with fertility.
Our editorial summary of this paper, not the article's abstract.
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 language were 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
From 698 references, 11 studies (5 of endometrial cancer and 3 each of ovarian and breast cancer) met the inclusion criteria for the meta-analysis (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). However when studies which included women aged over 54 years were excluded from the analysis, the risk for women with 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 first meta-analysis to examine gynaecological cancers in women with PCOS younger than 54 years of age compared with controls of similar age. Current data suggest that women of all ages with PCOS are at an increased risk of endometrial cancer but the risk of ovarian and breast cancer was not significantly increased overall. These results highlight the potential risk of gynaecological cancer morbidities associated with PCOS. However, the available evidence is far from robust and variation in diagnostic criteria for PCOS, 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 cancer must be judged in the context of its relatively low incidence in the general population. A large well-controlled prospective study is required in order to gain a more accurate estimate of the risk of gynaecological cancers in women with PCOS.
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