Abstract: ObjectiveTo investigate the clinical pathologic characteristics and prognosis of bilateral breast cancer, and to determine whether clinical factors is related to p53 gene mutation. MethodsArchival material was reviewed from 48 cases of bilateral breast cancar. The clinical and pathological features of bilateral breast cancer were compared and summarized. Immunohistochemical stains for P53 were performed on 33 cases of bilateral breast cancer, 141 cases of unilateral breast cancer were also examined as control. ResultsThe fiveyear survival rate for bilateral breast cancer patients was 70.5%. The median age when bilatereral breast cancer first dignosed was 47.5 （range from 27 to 69）. The median time interval between the first and the subsequent breast cancer diagnosis was 9.5 months. Invasive ductal breast carcinoma was the main pathologic type of bilateral breast cancer. 88.5% of bilateral breast cancer would have the same estrogen receptor (ER) status and 81.8% would have the same human epidermal growth hormone receptor 2 (HER2) status between the first and secondary primary tumors. Mutation p53 was more common among the bilateral breast cancer patients compared with the unilateral breast cancer patients （45.5% vs. 26.2%, χ2＝4.711，P＝0.030）. There was no difference on the overall survival between bilateral breast cancer with p53(+) and p53(-)（χ2＝0.434，P＝0.510）. ConclusionThe main pathologic type of bilateral breast cancer is invasive ductal breast carcinoma, there is a good match of the ER and HER2 status between the first breast cancer and the contralateral one. Bilateral breast cancer patients have a similar overall survial with the unilateral breast cancer. p53 mutation is more common among bilateral breast cancer patients than those with unilateral breast cancer.

Key words: Breast neoplasms, Pathology  clinical, Genes p53, Second primary