PERFORM: An epidemiological, prospective cohort study for patients with HR+/HER2- advanced breast cancer treated 1st-line with an endocrine-based palbociclib combination therapy in real world in Germany and Austria - Lux, MP; Resch, T; Fuxius, S; Gabrysiak, T; Amann, E; Buncke, J; Frank, M; Runkel, ED; Thill, M (Senologie - Zeitschrift für Mammadiagnostik und -therapie, 2021)