Investigation of potential salivary biomarkers for the diagnosis of breast cancer

145 Background: Saliva is an easily accessible and informative biological fluid which has high potential for the early diagnosis of diseases. Saliva-based diagnostics, particularly those based on metabolomics technology, offer a promising clinical strategy by characterizing the association between salivary analysts and a particular disease. The aim of this study is to investigate potential biomarkers in human saliva to facilitate the early diagnosis of breast cancer. Methods: We conducted a comprehensive metabolite analysis of saliva samples obtained from 60 breast cancer patients and 20 healthy controls, using capillary electrophoresis time-of-flight mass spectrometry (CE-TOF-MS). Statistical analyses were performed by using a nonparametric Mann-Whitney U test, multiple logistic regression and the receiver operating characteristics (ROC) to evaluate the predictive power of biomarkers. Results: Forty-nine patients (81.7 %) had invasive ductal carcinoma (IDC) and 9 patients (15.0 %) had ductal carcinoma in situ. In 33 patients receiving neoadjuvant treatment, saliva samples were obtained just before surgery. After removing the concomitantly observed peaks and noise peaks, an average of 205 peaks were derived from the metabolites. Among these peaks, five potential salivary biomarkers demonstrated significantly higher concentrations in breast cancer patients comparing with healthy individuals (p < 0.05). Especially, salivary biomarkers obtained from patients with IDC before neoadjuvant treatments tended to be higher concentrations than those obtained after treatment. In these metabolites, the area under the ROC curves (AUCs) were 0.765 for substance A, 0.716 for substance B, 0.809 for substance C, 0.819 for substance D and 0.850 for substance E. Conclusions: Salivary metabolites are promising biomarkers for the early diagnosis of breast cancer.