Objective:To evaluate the diagnostic significance of sublingual nodules for metastasis of patients with breast cancer and further to explore the mechanisms of sublingual nodules.Methods:The image data of 117 in-patients with breast cancer in stage Ⅰ-Ⅳ in Tianjin Medical University Cancer Institute and Hospital from December 2009 to September 2011 were assessed retrospectively.All photos of patients\' tongue were recorded by the digital camera of uniform type within 1 month after serological examination and regular re-examined by computed tomography (CT),magnetic resonance imaging and positron emission tomography CT.The presence of sublingual nodules was the positive standard.Chi square test and two-independent-sample test were used to determine the diagnostic value between the status of sublingual nodules and Clinico-pathological characteristics.The optimal cut-off of uric acid (UA) level to diagnose sublingual nodules was determined by receiver operating curve (ROC) analysis.Results:Breast cancer patients with sublingual nodules had a higher risk of recurrence and/or metastasis than patients without it (P＜0.001).Sublingual nodules was significantly correlated with increased serum UA level (P=0.001).The optimal cut-off value of UA level to diagnose sublingual nodules was 290 μ mol/L.Furthermore,the elevated serum UA level (≥290 μ mol/L) was significantly related to breast cancer recurrence and/or metastasis (P＜0.001).Conclusions:Sublingual nodules were potential diagnostic markers for metastatic breast cancer.The formation of sublingual nodules was associated with elevated level of serum UA.