Abstract A41: Fruit and vegetable intake and urinary levels of prostaglandin E2 metabolite among postmenopausal women

Abstract

Abstract Background: Prostaglandin E2 (PGE2) is a lipid mediator derived from COX-2 that plays key roles in promoting tumor development and progression. Recent studies have suggested urinary concentration of a major PGE2 metabolite (PGE-M) as a promising cancer biomarker. Diet and lifestyle factors may contribute to endogenous PGE2 production, determined by urinary PGE-M. We previously reported that smoking, obesity and fat intake were associated with increased levels of urinary PGE-M. Using data from 600 postmenopausal women in the Sister Study, a national prospective cohort of 50,000 U.S. women, we examined whether increased fruit and vegetable consumption would be associated with reduced levels of urinary PGE-M. Methods: A major urinary metabolite of PGE2 (11-α-hydroxy-9,15-dioxo-2,3,4,5-tetranor-prostane-1,20-dioic acid) was quantified using liquid chromatography/tandem mass spectrometry (LC/MS/MS). Dietary intake of fruits and vegetables were computed using the 1998 version of the full-diet Block Food Frequency Questionnaire, which contained 23 vegetable items (13 as a sole dish and 10 as a mixed dish), 10 fruit items (5 seasonal and 5 year-round fruits) and 6 juice items. A diet quality score was computed using the Healthy Eating Index (HEI). For regression analysis, urinary PGE-M concentration was log-transformed to improve the normal distribution of the data. Multiple linear regression models included the following potential confounding factors identified using a directed acyclic graph (DAG) analysis: age, body mass index, smoking status, diagnosis of breast cancer during the follow-up, lifetime use of nonsteroidal anti-inflammatory drug (NSAID), NSAID use in the past 24 hours, energy intake and percent of energy intake from saturated fat. Results: The median intakes of fruits and vegetables were 1.5 servings/d and 3 servings/d, respectively. Increasing fruit consumption was associated with lower levels of urinary PGE-M (p for linear trend=0.02). After multivariable adjustment, the geometric mean urinary PGE-M was 5.8 (95% CI: 5.2-6.6) in the lowest quintile, 5.3 (95% CI: 4.7-5.9) in the middle quintile (Q3) and 4.8 (95% CI: 4.3-5.4) in the highest quintile (Q5). Higher quality diet, as indicated by higher scores on the HEI, was also inversely associated with urinary PGE-M (p for linear trend<0.01). However, no significant association was observed between vegetable intake and urinary levels of PGE-M, which may reflect differential antioxidant capacity of specific dietary sources of fruits and vegetables. Conclusion: In the same cohort, we previously observed elevation in urinary PGE-M in relation to higher intake of fat. Together with the present results, findings suggest that urinary PGE-M may be modifiable by a healthy diet. Further studies are warranted to assess potential utility of urinary PGE-M in assessing cancer prevention efficacy. Citation Format: Sangmi Kim, Joseph Rimando, Dale P. Sandler. Fruit and vegetable intake and urinary levels of prostaglandin E2 metabolite among postmenopausal women. [abstract]. In: Proceedings of the Twelfth Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2013 Oct 27-30; National Harbor, MD. Philadelphia (PA): AACR; Can Prev Res 2013;6(11 Suppl): Abstract nr A41.