Feasibility of Cadmium Exposure Measurement Through Saliva in the Marin Women's Study

Background: To our knowledge, no studies have examined Cadmium (Cd) from saliva samples in the context of breast cancer as a potentially less invasive, cost effective method. In this pilot study, we assessed the feasibility of using saliva-based Cd levels as a predictor in breast density measures in Marin County, California as this community has a history of one of the highest incidences of breast cancer in the United States, thus making it a crucial population to study. Methods: This study used samples from the Marin Women’s Study (MWS) which recruits participants from Marin County mammography centers within Kaiser Permanente, Sutter Health, and Marin General Hospital locations. Cd was measured in 290 women who met inclusion criteria using mass spectrometry, and included all smokers in the sample for comparison (n=34). Each subject underwent a screening mammogram; and subsequent Single-energy X-ray Absorptiometry (SXA) measurement, which is a quantitative measure of fibrogladular tissue volume and been found to be both accurate and precise in measuring breast density. Additionally, each mammogram result was reviewed by a radiologist and assigned a Breast Imaging-Reporting and Data System (BI-RADS) score, a qualitative measurement of breast density. Results: Cd was quantifiable and detectable over 90% of saliva samples. The levels varied from the lowest detectable level of 12 pg/L to over 20 pg/L. As expected, Cd was higher in smokers. Preliminary analysis shows both SXA and BIRADS varied in women with higher saliva concentrations of Cd. Further analysis is needed understand confounding factors such as age, BMI, and dietary measurements. Discussion: These results show cadmium can be detected in saliva, while more work is needed to establish a more robust testing protocol before its usefulness can be qualified and quantified. Therefore, there is feasibility in using saliva to detect Cd in larger epidemiological studies.