Abstract 4825: Serum selenium concentration and risk of colorectal cancer in postmenopausal women: The Women's Health Initiative Observational Study

Abstract

Abstract In vitro and animal experimental studies have reported beneficial effects of selenium on colorectal cancer (CRC), yet results from epidemiological studies are inconsistent. Few of these studies have examined CRC risk among women, and none have been sufficiently large to examine risk in subgroups. This study investigated whether baseline serum selenium concentration was associated with subsequent CRC risk among postmenopausal women in a case-control study nested within the Women's Health Initiative Observational Study. We included 804 CRC cases diagnosed between October 1993 and September 2005 and 804 controls matched to cases on age, enrollment date, clinical center, race/ethnicity, hysterectomy status, and prevalent condition at baseline. Baseline serum selenium concentration was measured by atomic absorption spectrometry. Multivariate logistic regression was used to estimate the odds ratios (OR) and 95% confidence intervals (95% CI) associated with increasing serum selenium concentrations. The corresponding median selenium concentrations in the 1st to 5th quintiles were 110.5, 123.2, 133.5, 144.8, and 162.2 µg/l (range: 81.03 - 398.70 µg/l). The selenium concentration was weakly and positively associated with the risk of CRC (ptrend = 0.08); the adjusted ORs (95% CIs) for the risk of CRC comparing the 2nd, 3rd, 4th, and 5th quintile of serum selenium concentrations with the 1st quintile were 1.14 (0.83-1.58), 1.16 (0.84-1.60), 1.36 (0.99-1.87) and 1.27 (0.92-1.76). The trend was somewhat stronger for past and current smokers [OR (95% CI) for the 5th vs. 1st quintile = 1.38 (0.89-2.13), ptrend = 0.13] than never smokers [OR (95% CI) for the 5th vs. 1st quintile = 1.16 (0.72-1.87), ptrend = 0.48]. However, the difference was not statistically significant (pinteraction = 0.53). Findings from this large study with relatively high serum selenium concentrations suggest no beneficial effect of selenium on colorectal cancer among women, which is consistent with results of previous smaller observational studies. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4825.