Abstract:Objective:To investigate the expression of osteopontin（OPN） mRNA in breast tissues containing microcalcifications and the significance of OPN in tumor pathogenesis and metastasis of breast cancer. Methods:The expression of OPNmRNA in 128 samples of tissues of breast lesions and adjacent breast tissues and 9 samples of metastatic lymph nodes were examined. Results:The expression of OPNmRNA was highest in calcified foci of breast cancer tissues and in metastatic lynph nodes, lower in calcified foci of benign breast tissues and lowest in breast tissues adjacent to breast cancer and in benign tissues without calcification.The differences between the defferent tissues were significant(all P<0.05). Conclusions:Expression of OPNmRNA is related to calcification of breast cancer tissue and to the development of breast cancer.Determination of OPNmRNA expression can be expected to be a guide to clinical therapy and prediction of the prognosis of breast cancer patients.