Risk of cancers in women with polycystic ovary syndrome: Cohort study based on health insurance database in South Korea.

[OBJECTIVE] To evaluate the risk of all cancer types associated with polycystic ovary syndrome (PCOS) in a Korean population-based study.

[METHODS] This retrospective cohort study used national health checkups and insurance data between January 1, 2011, and December 31, 2020. Women aged 20-50 years who attended medical institutions for PCOS or underwent health checkups were included. In total, 774 811 participants were included. The PCOS and non-PCOS groups comprised 127 980 and 563 850 patients, respectively. After 1:1 propensity score matching, each group consisted of 127 712 participants. Hazard ratios were evaluated for all types of cancers associated with PCOS across age groups.

[RESULTS] Demographic and clinical characteristics of women with and without PCOS were not significantly different. However, in the PCOS group, the total cancer risk increased (hazard ratio: 1.156, 95% confidence interval: 1.058-1.263, P = 0.001), and the risk of uterine and ovarian cancers increased (hazard ratio: 4.963, 95% confidence interval: 3.282-7.504, P < 0.001; hazard ratio: 1.774, 95% confidence interval: 1.142-2.755, P = 0.011, respectively). The risk of thyroid cancer increased in the 20-29 years age group within the PCOS group (hazard ratio: 1.2, 95% confidence interval: 1.009-1.427, P = 0.039).

[CONCLUSION] PCOS is associated with an increased risk of uterine and ovarian cancers. An increased risk of thyroid cancer was associated with PCOS in the 20-29 years age group. However, no link was found between PCOS and breast cancer. This should be considered when treating patients with PCOS.