Cadmium and breast cancer among U.S. women age 30 years and older, NHANES 1999-2006

Introduction: Breast cancer is the most prevalent women's cancer worldwide. A two-fold greater odds for breast cancer among women with urine cadmium levels above 0.58 ug cadmium per g creatinine (ug/g) was shown in a regional case-control study; however, the risk for a U.S. probability sample has not been previously reported. This study aims to evaluate the odds for breast cancer associated with urine cadmium levels among U.S. women age 30 and older.

Methods: Data were obtained from the National Health and Nutrition Examination Survey for years 1999-2006 (N=2,418). Breast cancer was indicated by self report of physician diagnosis; urinary cadmium was measured by the Centers for Disease Control. Urinary cadmium was adjusted for creatinine and evaluated for association with breast cancer using multivariable logistic regression analysis.

Findings: Relative to the lowest urine cadmium (UCd) quartile (<0.25 ug/g), women with the highest UCd quartile (>0.65g/g) showed three-fold greater odds for breast cancer, controlling for age, BMI, race/ethnicity, smoking, alcohol intake, hormonal use, older age at first live birth/nullipara, and menopause (OR=3.10; 95% CI=1.05, 9.15; p=0.041). The third quartile (UCd >0.40 and <0.65 ug/g), was significantly associated with 2.67 greater risk (OR=2.67; 95% CI=1.09, 6.54; p=0.03).

Conclusion: Results suggest that U.S. women, age 30 years and older, are at increased risk for breast cancer at higher urine cadmium levels, independent of established risk factors. Further research is merited to discern the interplay between cadmium exposure and genetic susceptibility, and sources of exposure.