摘要:Background: Breast cancer is the most common cancer in women. Prostate ? specific antigen (PSA) is a marker of prostate gland malignancy, which has been considered in cases with breast cancer in recent years. The goal of this study was to determine total and free PSA levels in cases with malignant and benign breast lesions. Methods: In this case–control study, ninety women with histological proved malignant breast masses and 90 with benign breast masses were enrolled. Total and free PSA levels along with Histological grade and conditions of vascular and perinural invasion, status of hormonal tumor receptors, immune ? histo ? chemistry markers recorded for all cases. Total and free PSA levels were assessed after treatment in cases with malignant masses. Results: Total and free PSA levels were significantly higher in cases with malignant masses. The best cut ? off point for total PSA to differentiate benign and malignant masses was 0.31 with sensitivity and specificity of 100%, 100% (area under the curve [AUC] =1, P<0.001) and the best cut ? off point for free PSA to differentiate benign and malignant masses was 0.19 with sensitivity and specificity of 100% and 100% (AUC = 1, P<0.001). After treatment, mean free PSA level was significantly lower than free PSA before treatment (0.23±0.1 vs. 0.3±0.08, P<0.001). Conclusions: Serum PSA level could be applied for differentiating benign and malignant breast masses.