The combination CDK4/6 inhibitors (CDK4/6i) (Palbociclib, Ribociclib and Abemaciclib) with endocrine therapy (ET, i.e. aro- matase inhibitors (AI) or Fulvestrant) has significantly increased objective response rate (ORR) and progression-free survival (PFS) of first- and second-line treatments in patients with hormone receptor positive, HER2 negative (luminal) mBC. Now this combination is the standard treatment for luminal mBC. Recommendation for endocrine therapy versus chemotherapy as first-line treatment of luminal mBC is endorsed by the main international guidelines such as ASCO and ESO-ESMO guidelines. Endocrine therapy should be used as initial treatment except in cases of immediately life-threatening disease, tumors refractory to endocrine therapy, visceral crisis, or rapid progressive disease that mandate a high response rate treatment. The aim of this study is to provide real-life treatment patterns data for luminal MBC with a focus in population of Moscow
