Correlation of Her-2 overexpression with endocrine status and response to tamoxifen treatment in patients with breast cancer

Abstract

To investigate the correlation of Her-2 overexpression with endocrine status and response to tamoxifen treatment in patients with breast cancer. Immunohistochemistry was used to measure the expression of estrogen receptor (ER), progesterone receptor (PR), Her-2, p53, proliferating cell nuclear antigen (PCNA) in 4773 consecutive in-hospitalized patients with primary breast cancer confirmed by pathological examination of the resected specimens, all females, aged 50 (15 - 92), and were followed up for 42 months on average. 1090 if then received tamoxifen (TAM), an anti-estrogen agent, post-operationally. The correlation of Her-2 overexpression with other factors was analyzed. (1) The Her-2 overexpression rate was 26.6%. Her-2 overexpression was significantly negatively correlated with expressions of ER and PR (both P < 0.01). (2) The general 3-year disease-free survival (DFS) rate of those treated with TAM was 92.7%; and the 3-year GFS rate of the subgroup of the TAM-treated patients with Her-1 overexpression was 91.2%, significantly lower than that of those without Her-2 overexpression (93.4%, P = 0.004). (3) The 3-year DFS rate premenopausal patients with Her-2 overexpression was 91.8%, not significantly different from that of those without Her-2 overexpression (92.6%, P > 0.05), however, the 3-year DFS rate of the postmenopausal patients with Her-2 overexpression was 90.4%, significantly lower than that of those without Her-2 overexpression (92.6%, P = 0.010). (4) The 3-year DFS rate of the axillary lymph node-positive patients with Her-2 overexpression was 89.1%, significantly lower than that without Her-2 overexpression (92.3%, P = 0.037). (5) In the premenopausal patients there was no significant difference in the 3-year DFS rate between the lymph node-negative patients with and without Her-2 overexpression (P > 0.05). However, in the postmenopausal lymph node positive patients the 3-year DFS rate of those with Her-2 overexpression was 88.7%, significantly lower than that of those without Her-2 overexpression (92.2%, P = 0.0069). ER and PR are independent factors of Her-2 expression. Her-2 overexpression signifies resistance to TAM treatment. The response to TAM is not influenced by the Her-2 expression and axillary lymph node metastasis status in the premenopausal patients, and is not influenced by the Her-2 expression level in the postmenopausal patients.