Even early-stage breast cancer is a heterogeneous disease, so the optimal treatment depends on the pathological characteristics of the tumor. The vast majority of breast tumors (80%) are classified as estrogen receptor positive (ER+) with varying degrees of ER expression. The benefit of endocrine therapy is small with low ER staining (1–10%), occurring in less than 2% of all cases of ER+ breast cancer. Genetic analyzes are valuable for administration of adjuvant chemotherapy prior to endocrine therapy in ER+ / HER2– pN0–pN1c breast cancer. But such tests are not yet widely available. In practical work, when planning adjuvant and neoadjuvant therapy for patients with ER+ / HER2– breast cancer, pathological assessment of the expression of ER, PR, Ki‑67, as well as the tumor grade (G) remains important. The use of drugs to overcome resistance to endocrine therapy: PI3-kinase inhibitors (taselisib), CDK 4/6 inhibitors (palbociclib, abemaciclib, ribociklib), mTOR inhibitors (everolimus) can enhance the effect of neoadjuvant and adjuvant endocrine therapy.
Update 2010 of the German AGO Recommendations for the Diagnosis and Treatment of Early and Metastatic Breast Cancer – Chapter A: Surgery, Pathology and Prognostic Factors, Adjuvant and Neoadjuvant Therapy, Adjuvant Radiotherapy