Abstract B08: Urinary PGE-M levels and risk of ovarian cancer

Abstract

Abstract Introduction: Prostaglandin E2 (PGE2) is thought to influence ovarian carcinogenesis by increasing cell proliferation, tumor cell invasiveness, and angiogenesis. PGE-M is the major metabolite of PGE2 and a marker of systemic PGE2 production. Prior research has reported positive associations between urinary PGE-M and risk of colorectal, gastric, lung, pancreatic, and breast cancer; however, this is the first study to evaluate the association between urinary PGE-M and risk of ovarian cancer. Methods: We conducted a prospective case-control study nested in the Nurses’ Health Study (NHS) and NHSII cohorts. We included 194 cases of invasive epithelial ovarian cancer and 387 matched controls. All cases were diagnosed between the time of urine specimen collection (1996-97 NHSII; 2000-2002 NHS) and the end of follow-up (2015). Controls were selected using incidence density sampling and matched to cases on year of birth, menopausal status at collection and diagnosis, date and time of day of collection, hormone therapy use at collection, and fasting status. We measured PGE-M levels using LC/MS methods, and used the PGE-M distribution among controls to identify tertile cutpoints. We estimated the association between prediagnosis urinary PGE-M (in tertiles) and risk of ovarian cancer using conditional logistic regression. Results: We observed a suggestively lower risk of ovarian cancer for those with the highest PGE-M levels in NHS (OR=0.66; 95%CI=0.36-1.21; p-trend=0.15; n=123 cases), and no association in NHSII (OR=1.15; 95%CI=0.50-2.67; p-trend=0.75; n=71 cases). When results from the two cohorts were pooled, we observed nonsignificant, lower odds of ovarian cancer among those in the highest tertile of PGE-M compared to the lowest tertile (OR=0.80; 95%CI=0.50-1.27; p-trend=0.34), particularly after restricting our analysis to study participants who provided first morning urine samples (OR=0.68; 95%CI=0.40-1.14; p-trend=0.13). However, when we examined quartiles, no clear association was observed, although power was limited. Conclusions: Overall, our results suggest that higher prediagnosis PGE-M levels are not associated with an increased risk of ovarian cancer. Further analyses are under way to evaluate the potential for effect modification by menopausal status, BMI, and NSAID use. Citation Format: Mollie E. Barnard, A. Heather Eliassen, Bernard A. Rosner, Kathryn L. Terry, Ginger L. Milne, Shelley S. Tworoger. Urinary PGE-M levels and risk of ovarian cancer. [abstract]. In: Proceedings of the AACR Conference: Addressing Critical Questions in Ovarian Cancer Research and Treatment; Oct 1-4, 2017; Pittsburgh, PA. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(15_Suppl):Abstract nr B08.