The use of neoadjuvant hormone therapy in locally advanced luminal breast cancer

Background. Chemotherapy is used for neoadjuvant systemic therapy of locally advanced breast cancer, including the luminal HER2-negative subtype. However, there is evidence suggesting the possibility of using neoadjuvant hormone therapy (NGT) in this category of patients. It is necessary to develop a differentiated approach of neoadjuvant systemic therapy for the highly heterogeneous luminal HER2-negative breast cancer. The aim of our study was to understand the effectiveness of NGT in patients with potentially highly hormone-sensitive tumors.

Materials and methods. The study involved patients with locally advanced stages (T2-4N2-3M0) of hormone-dependent HER2-negative breast cancer with a high level of expression of estrogen and progesterone receptors (7–8 points according to Allred) and a low level of index Ki67 (<30%) who received NGT with tamoxifen or aromatase inhibitors in the preoperative period.

Results. Sixty patients were included in the study, 96.7% of them achieved operable condition (2 patients were transferred to chemotherapy). Complete clinical response was achieved in 2 patients (3.3%), stabilization in 13 (21.7%), and a partial response in 43 (71.7%). The progression of the disease was detected in 5/60 (8.3%). With a median follow-up time of 39 months (6-109), the 4–year disease-free survival was 93.6%. Adjuvant chemotherapy (ACT) was given to 23/58 (39.7%) patients, among them 4 developed disease progression. Of the 35 patients who did not receive ACT, no cases of progression were noted.

Conclusions. Our results demonstrate high effectiveness of NGT in patients with luminal HER2 negative breast cancer with the above characteristics of tumor biology.