Abstract: Purpose : To study the relationship between p53 gene mutation and the prognosis of breast cancer ,and the relationship of the expression of p53 , Bcl-2 , C-erbB-2 , PCNA and Ki67 to the occurance , development of breast cancer. Methods : PCR-SSCP and immunohistochemical SP methods were used. Results : The p53 gene mutation and LOH (loss of heterozygosity) coincided with those bad prognostic factors such as high expression of PCNA , absence of ER and PR( P < 0. 05 or P < 0. 01) . The expressions of p53 , C-erbB-2 , PCNA and Ki67 were notably increased in the occurance and development of breast cancer ( P < 0. 05 or P < 0. 01) ,but the expression of bcl-2 decreased. Conclusion : p53 gene mutation (particularly LOH) is bad prognostic factor and marker of breast cancer. The high expressions of p53 , C-erbB-2 , PCNA and Ki67 are the factors and markers of the occurance and development of breast cancer , and particularly , the expressions of C-erbB-2 , PCNA and Ki67 are the indicators of breast carcinogenesis.

Key words: breast cancer, atypical hyperplasia, p53, Bcl-2, C-erbB-2, PCNA, Ki67