Objective  To explored the survival benefit and prognostic factors of patients receiving chemotherapy or endocrine±targeted therapy after palbociclib treatment in patients with HR+/HER2-metastatic breast cancer (HR+/HER2-MBC).

  Methods  We identified patients who had been diagnosed with HR+/HER2-MBC and had received palbociclib-based therapy at Tianjin Medical University Cancer Institute & Hospital between August 2018 and December 2022. Clinical information, progression-free survival (PFS), and overall survival (OS) of patients on palbociclib treatments were collected from medical records and outpatient facilities.

  Results  72.2% of patients were treated with rescue chemotherapy prior to palbociclib, 66.2% received palbociclib≥3 lines at baseline in MBC setting, 67.7% were treated with chemotherapy after progression on palbociclib, and 69.2% had ≥3 metastatic organs. Differences were observed between chemotherapy group versus endocrine±targeted therapy in PFS (3.2 months vs. 4.9 months; P=0.017) and OS (18.2 months vs. 21.5 months; P=0.019). Multivariate analysis found no independent prognostic factors that affected PFS or OS.

  Conclusions  Chemotherapy is the first choice for most patients with HR+/HER2-MBC after palbociclib treatment failure; however, PFS and OS are longer in patients receiving endocrine± targeted therapy than in those receiving chemotherapy.