Background: The aim of this study is to examine the association of urinary cesium with breast cancer risk.
Materials and methods: We collected survey data and urine specimens from 240 women with incident invasive breast cancer before their treatment and 246 age-matched female controls between October 2009 and July 2010. Urinary concentrations of cesium were determined by inductively coupled plasma mass spectrometry. Interviews were conducted by face-to-face to obtain information on potential breast cancer risk factors. Logistic regression analysis was used to estimate the associations.
Results: Creatinine-adjusted levels [median (25th, 75th) ug/g] of cesium in cases and controls were 17.6 (13.1, 24.0) and 19.3 (15.3, 25.7), respectively. After adjustment for potential risk factors, women in the second and highest tertile of cesium showed a decreased risk of breast cancer in a dose-dependent manner as compared with those in the lowest tertile [ORs and 95% CIs: 0.75 (0.46- 1.22) and 0.50 (0.30-0.82), respectively]. This decrease was more evident in women with ER positive or localized clinical stage in an exploratory stratification analysis.
Conclusions: These findings suggest that cesium may have anticancer efficacy and urinary cesium has potential as a biomarker for breast cancer risk assessment.