Abstract 2293: Oligomenorrhea, polycystic ovary syndrome, and risk of ovarian cancer histotypes, evidence from the Ovarian Cancer Association Consortium
Authors: Harris Holly R. , Jordan Susan , Risch Harvey , Rossing Mary Anne , Goodman Marc T. , Modugno Francesmary , Kjær Susanne Krüger , Schildkraut Joellen M. , Bandera Elisa V. , Wentzensen Nicolas , Phelan Catherine , Anton-Culver Hoda , Wu Anna H. , Terry Kathryn L. 
Published: July 2017

Abstract
Background: Oligomenorrhea, defined as infrequent or irregular periods has been shown to be associated with epithelial ovarian cancer risk in some but not all studies. Polycystic ovary syndrome (PCOS), which is characterized by oligomenorrhea and abnormal hormone levels including hyperandrogenism, hyperinsulinemia, and gonadotropin imbalance, has been suggested to increase ovarian cancer risk. However, these associations have been rarely examined by histologic subtype. We sought to examine these associations among 14 studies participating in the Ovarian Cancer Association Consortium.
Methods: Participants included 16,594 patients with invasive (n=13,719) or borderline (n=2,875) ovarian cancers and 17,718 controls who had answered questions regarding menstrual cycle irregularity, menstrual cycle length, and/or PCOS. Study specific odds ratios (ORs; 95% confidence intervals [95% CI]), adjusted for ovarian cancer risk factors, were calculated and then combined using a random-effects meta-analysis. Pooled histologic subtype specific ORs (95% CI) were calculated using polytomous logistic regression.
Results: Women reporting menstrual cycle length &gt;35 days had decreased risk of invasive ovarian cancer compared to women reporting cycle length ≤35 days (OR=0.70; 95% CI=0.58-0.84). Decreased risk of invasive ovarian cancer was also observed among women who reported irregular menstrual cycles compared to women with regular cycles (OR=0.83; 95% CI=0.76-0.89). No significant association was observed between self-reported PCOS and invasive ovarian cancer risk (OR=0.87; 95% CI=0.65-1.15). For menstrual cycle length &gt;35 days, decreased risk was observed for all invasive histotypes: low grade serous (OR=0.48; 95% CI=0.25-0.92), high grade serous (OR=0.62; 95% CI=0.48-0.80), mucinous (OR=0.38; 95% CI=0.19-0.76), endometrioid (OR=0.75; 95% CI=0.54-1.06), and clear cell (OR=0.70; 95% CI=0.43-1.13) but not for serous borderline tumors (OR=1.18; 95% CI=0.87-1.59) (pheterogeneity=0.006). An increased risk of serous borderline disease was observed among women reporting irregular cycles (OR=1.34; 95% CI=1.16-1.55) (pheterogeneity&lt;0.0001). No statistically significant differences by histologic subtype were observed for self-reported PCOS.
Conclusion: In this large consortium analysis we observed a decreased risk of most invasive epithelial ovarian cancer histotypes among women reporting longer or irregular menstrual cycles. In contrast, such cycles were associated with increased risk of the serous borderline tumors.
Citation Format: Holly R. Harris, Susan Jordan, Harvey Risch, Mary Anne Rossing, Marc T. Goodman, Francesmary Modugno, Susanne Krüger Kjær, Joellen M. Schildkraut, Elisa V. Bandera, Nicolas Wentzensen, Catherine Phelan, Hoda Anton-Culver, Anna H. Wu, Kathryn L. Terry. Oligomenorrhea, polycystic ovary syndrome, and risk of ovarian cancer histotypes, evidence from the Ovarian Cancer Association Consortium [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2293. doi:10.1158/1538-7445.AM2017-2293