PCOS and breast cancer risk: hormonal modulation and epidemiological trends

BACKGROUND: Hormonal signals intricately regulate breast growth and development. Any perturbations due to altered endocrine and metabolic conditions, such as in polycystic ovary syndrome (PCOS), may influence breast cancer risk. This review highlights the susceptibility of women with PCOS to breast cancer, with a focus on the potential contribution of its comorbidities, such as hyperandrogenism, obesity, insulin resistance, diabetes, menopausal status, inflammation, and use of ovulation induction agents to this association. METHODS: This is a narrative review including articles and information collected from PubMed, Scopus, Google Scholar, and the World Health Organization (WHO) websites. Studies were selected based on the availability of an abstract and research publication in English. Reports related to PCOS, its characteristics (hyperandrogenism, hyperinsulinemia, insulin resistance, type 2 diabetes, obesity), fertility treatment, and their association with breast cancer were included. RESULTS: The interrelation between PCOS and breast carcinoma remains ambiguous due to inconsistent and inconclusive epidemiological evidence. The comorbidities associated with the condition are reported to collectively or individually influence this association. Women with PCOS present anovulatory cycles and have a high necessity of undergoing ovulation induction, further altering hormonal dynamics. Evidence in the literature suggests that the number of treatment cycles, age at the onset of treatment, and cumulative doses of agents used for ovulation induction are a few other factors that could affect breast cancer risk, though the results are inconclusive. CONCLUSION: Existing literature suggests that PCOS and its characteristics may impact the process of breast development and possibly contribute to breast cancer, although the evidence is still conflicting. Moreover, temporary alterations of endocrine profile following fertility medications may have a significant influence on the breast cancer risk, although research has shown inconclusive evidence. Hence, robust experimental studies are required to understand the underlying mechanisms and the long-term health implications for women with PCOS due to the intricate association between these factors.