Abstract: Objective : To explore the excision extension for breast conservative surgery which is suitable for Chinese women. Methods : 48 cases of negative margin specimen of BCS and -2 specimen of mastectomy were examined using whole specimen section, immunohistochemistry and molecular biology methods to observe pathological changes and expressions of PCNA, P53 and C-erbB-2 in primary tumor and paracarcinoma tissues. Results : Along with the further distance from primary tumor, the proportions of high risk disease and positive expressions of PCNA, C-erbB-2 and P53 in paracarcinoma tissue were decreased gradually (P<0.05). Disease extension in paracarcinoma tissue was related to extensive intraductal component and positive expressions of C-erbB-2 and P53 (P<0.05). Conclusion :Risk factors of local recurrence after BCS were mainly(95.2%) existed within 2cm nearby primary tumor in clinical stage I and II breast cancer. It is recommended that 2cm nearby primary tumor is safe extension for BCS,and it is necessary to choice individual treatment for breast cancer with different clinico-pathologic characteristics.