Hormone receptor alterations and treatment responses after neoadjuvant therapy in patients with ER+/HER2- breast cancer.

Abstract

e11605 Background: Hormone therapy is recommended for treating patients with luminal A type early breast cancer by the International Conference in St. Gallen, 2011. However, precisely which neoadjuvant therapeutic strategies are optimal for such patients still remains controversial. We retrospectively evaluated the treatment responses to neoadjuvant chemotherapy (NAC) or neoadjuvant endocrine therapy (NAE) in patients with ER (+)/HER2 (-) breast cancer. Methods: Four hundred and sixty-one patients with primary breast cancer underwent surgery between November 2007 and October 2012. Of 243 patients with hormone receptor (+)/HER2 (-) breast cancer, 63 with ER (+)/HER2 (-) breast cancer were preoperatively treated with either NAC (n=47, median age: 49 years) or NAE (n=16, median age: 63 years). Four cycles (c) of FEC 100 (epirubicin 100 mg/m2 + 5-fluorouracil and cyclophosphamide 500 mg/m2) followed by 4 cycles of Docetaxel (75 mg/m2) every 3 weeks were administered for the NAC treatment regimen, while Letrozole was administered for 6 months for the menopausal patients in the NAE treatment protocol. Results: NAC did not alter the ER status, while the ER status was decreased by NAE (from 83% to 62%). NAE altered the ER status (positive rate; from 83 % to 62 %), but NAC did not. The PR status was decreased by both NAC and NAE (from 51% to 30% and from 63% to 9%, respectively). ER (P=0.0327) and PR (P=0.0019) were statistically decreased after NAE compared to that observed after NAC. The response rates determined by RECIST {PD/SD/PR/CR (%)} in the NAC- and NAE-treated patients were 2/34/58/6 and 0/50/50/0, respectively. The rate of tumor shrinkage was 41% (3.9 to 2.3 cm) after NAC and 39% (2.3 to 1.4 cm) after NAE. The pathological complete response rate was 9% after NAC and 6% after NAE. The recurrence rate in the stage I/II patients was 5% (2/38) after NAC and 0% (0/16) after NAE for short-term outcomes. Conclusions: The hormone status significantly changed after NAE compared to that observed after NAC. Both of the NAC and NAE treatment protocols caused a decrease in the tumor size. As a result, both of these therapeutic modalities were found to improve the rate of breast-conserving surgery.