Introduction/Background Polycystic ovarian syndrome (PCOS) is a common endocrine disorder affecting approximately 4 to 12% of women of reproductive age. Whilst existing literature suggests an association between PCOS and endometrial cancer, the sparsity and inconsistency of current evidence indicate a lack of clarity on the exact strength of this association. It remains uncertain whether the degree of risk is affected by confounding factors such as age and BMI. The objective of this paper is to quantify the risk of endometrial cancer in women with PCOS compared to women of all ages, and specifically to premenopausal women.

Methodology We performed a systematic review and meta-analysis of all the studies that looked into the association between PCOS and endometrial cancer published up to January 2022 through PubMed, MEDLINE, EMBASE and Cochrane. Relevant data from these studies meeting inclusion criteria were extracted and analysed. The quality of included studies was assessed using the Newcastle-Ottawa Criteria.

Results A total of 10 studies were identified and included in the meta-analysis (12,248 women with PCOS and 54,120 controls). Women with PCOS had a significantly increased risk of developing endometrial cancer, compared with those without PCOS (OR 4.07, 95% CI 2.13–7.78, P<0.0001). When postmenopausal women (aged over 54 years) were excluded from the meta-analysis, this risk increased further. (OR 5.14, 95% CI 3.22–8.21, P<0.00001).

Conclusion This meta-analysis demonstrates that women with PCOS are up to five times more likely to develop endometrial cancer compared to those without PCOS. However, limiting factors such as variation in the diagnosis of PCOS and lack of adjustment for confounding factors within existing evidence may have led to the strength of this risk being inflated. Larger, prospective studies that are well controlled for other relevant risk factors are required to better ascertain the risk of endometrial cancer in women with PCOS.