Abstract: Objective To investigate the influence of tamoxifen on the postmenopausal women and test an assumption whether tamoxifen can cause the endometrial cancer by pten. Methods With PCR-SSCP method, sequence analysis and RT-PCR method, the authors examined the correlation of pten mutation of nine exons in endometrium of postmenopausal women with breast cancer who were taking tamoxifen.Results PCR-SSCP of pten and sequence analysis showed that 4/33 cases (12.12％) of tamoxifen group and 5/22 cases (22.72％) of endometrial carcinoma group had mutation. There was no mutation in normal endometrium group. The differences of pten mutation rate was not significant between tamoxifen and carcinoma groups, and between tamoxifen and normal endometrium groups, but was significant between endometrial carcinoma and normal endometrium groups. Conclusion Pten gene mutation may be a diagnostic biomarker for the early event leading to the cancer.

Key words: tamoxifen, phosphatase and tensin(pten) gene, endometrium, breast neoplasms