Maria Forslund

Polycystic ovary syndrome and the risk of ovarian tumours.

To explore the risk of ovarian cancer (OC) and its subtypes among women with PCOS. This is a retrospective cohort study with a follow-up of 25 years. The study included 479,759 participants, of which 80,131 were diagnosed with PCOS and 399,628 were matched controls (1:5 ratio). The data were obtained from Swedish registers, primarily the National Patient Registry and the Swedish National Cancer Registry. We used Cox regression to calculate hazard ratios, both crude and adjusted, and 95 % confidence intervals (95 % CI). During the study period, 450 individuals were diagnosed with OC or borderline tumour of the ovary (BOT). Following adjustment for obesity, country of birth and education, women with PCOS did not have an increased risk of epithelial ovarian cancer (EOC), aHR: 1.00 (95 % CI 0.64-1.55). However, the risks of developing BOT and non-EOC were higher in women with PCOS, aHR: 1.61 (95 % CI 1.16-2.23) and aHR: 4.26 (95 % CI 2.50-7.03), respectively. When further subgrouping non-EOC, stromal tumours stood out with a seventh-fold increased risk among women with PCOS. Women with PCOS are at higher risk of developing non-EOC and BOT than women without PCOS. Although the risk estimate is high, non-EOC is a rare diagnosis. Thus, the findings of this study may provide insights into the underlying mechanisms of PCOS and ovarian cancer, primarily non-EOC. However, they do not indicate any necessity for screening or alterations in the follow-up of women with PCOS.