Association between Polycystic Ovary Syndrome and Breast Cancer: A Review

Aims: Polycystic ovary syndrome (PCOS) is a common endocrine disorder seen in women of reproductive age. The hormonal profile and comorbidities seen in women with PCOS like obesity and diabetes are some of the main risk factors of breast cancer. The aim of this review is to investigate the plausible association between PCOS and breast cancer. This review focuses on the epidemiological evidence, association of PCOS-related symptoms and PCOS medications on the incidence of breast cancer.

Methodology: A comprehensive literature search using Ovid MEDLINE, Google Scholar and PubMed was performed to identify epidemiologic studies that have been published in the last 10 years (from 2010 to 25th June 2020) that reported on the association between PCOS and breast cancer. The following keywords were used: polycystic ovary syndrome, breast cancer and breast neoplasms.

Results: Most of the epidemiological studies did not observe significant association between PCOS and breast cancer. However, evidence shows that elevated androgen levels and estrogen levels are associated with increased risk of estrogen receptor positive breast cancer. In addition, this review found increased breast cancer risk in women with obesity, hyperinsulinemia and low level of sex hormone binding globulin. Unlike metformin and clomiphene citrate, combined hormonal contraceptive, being the first line treatment for PCOS is linked with higher breast cancer risk.

Conclusion: Clinical findings from this review are inconsistent, hence a firm conclusion cannot be made regarding the association between PCOS and breast cancer, emphasizing the need for more prospective studies to be conducted in the future.