The role of a «short-term» preoperative endocrine therapy for adjuvant therapy guidance in early HR+ HER2-negative breast cancer

In the absence of widespread access to genomic tests there is an urgent need for additional methods that influence the choice of adjuvant therapy in patients with early luminal Her2-negative subtype of breast cancer (BC). The IMPACT and POETIC trials have shown that Ki67 level decrease up to ≤10% after a “short-term” (2–4 weeks) preoperative endocrine therapy (ET) is a favorable prognostic factor. This test allows some patients to avoid adjuvant chemotherapy associated with immediate and delayed adverse events.

Aims of the study. To evaluate the impact of “short-term” preoperative endocrine therapy for guidance of further treatment for patients with primary operable luminal Her2-negative breast cancer stages T1–3 N0–1 M0.

Results. The study included 123 patients, 76 (60.8%) received tamoxifen and 47 (37.6%) – aromatase inhibitors (AI). Most patients – 69 (55.2%) were >50 years old, premenopausal – 58 (46.4%), menopausal – 67 (53.6%). The average age was 52 years (30–82). With the initial Ki67 level>10% (N= 107), Ki67 decreased in 24 (22.4%) up to ≤10% after “short-term” ET, and remained >10% in 83 (77.6%). According to the PREDICT calculator, the benefit of adjuvant chemotherapy (AChT) was assessed as high in 35 (28.5%) patients, and 10 of them (27.8%) were able to avoid Ch T. In 86 patients with a relatively low estimated AChT benefit (<5% at 10 years) there was no response to “short-term” ET, which led to the AChT prescription in 13 cases (15.1%).

Conclusions. “Short-term” course of preoperative endocrine therapy is a simple, accessible and reproducible method for personalizing of adjuvant therapy in patients with luminal HER2-negative breast cancer.

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