Comparison of estrogen receptor, progesterone receptor and Her-2 status in breast cancer pre- and post-neoadjuvant chemotherapy.

Neoadjuvant chemotherapy (NAC) is now a relatively standard treatment for breast carcinoma. However, some tumors are known to develop resistance to chemotherapies. We investigated whether the status of estrogen receptor (ER), progesterone receptor (PR) and Her-2 expressions in breast cancer cases prior to NAC could be changed after NAC. We used immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) methods. No differences were found in ER or Her-2 status, but a significant difference was found in PR status. Changes in Her-2 status were suspected in four specimens after NAC (3+ to 1+ for 3 patients, and 1+ to 3+ for one patient) according to the IHC results. However, in all four of these cases, FISH of the resections showed no change. When IHC indicates a change in Her-2 expression after NAC, FISH is recommended.