The study will describe the treatment effect for different patient groups in terms of age and comorbidities. Comorbidity is the condition of having two or more diseases at the same time. The data is collected by the Danish Breast Cancer Group in the period between 2017 to 2023. conditions: Breast Cancer studyType: OBSERVATIONAL observationalModel: COHORT timePerspective: RETROSPECTIVE count: 580 type: ESTIMATED name: Palbociclib in combination with AI measure: Progression-free Survival (PFS) of all mBC patients receiving palbociclib in combination with AI as first-line treatment measure: Overall Survival (OS) of all mBC patients receiving palbociclib in combination with AI as first-line treatment measure: Age distribution in the full data set of mBC patients receiving palbociclib + AI as first-line treatment measure: PFS in mBC patients below 65 years of age receiving palbociclib + AI as first-line treatment measure: PFS in mBC patients between 65-74 years of age receiving palbociclib + AI as first-line treatment measure: PFS in mBC patients 75+ years of age receiving palbociclib + AI as first-line treatment measure: OS in mBC patients below 65 years of age receiving palbociclib + AI as first-line treatment measure: OS in mBC patients between 65-74 years of age receiving palbociclib + AI as first-line treatment measure: OS in mBC patients 75+ years of age receiving palbociclib + AI as first-line treatment measure: PFS in the full dataset of mBC patients receiving palbociclib + AI as first-line treatment split into Charlson Comorbidity Index (CCI) point score of 0 measure: PFS in the full dataset of mBC patients receiving palbociclib + AI as first-line treatment split into CCI point score of 1 measure: PFS in the full dataset of mBC patients receiving palbociclib + AI as first-line treatment split into CCI point score of 2 measure: PFS in the full dataset of mBC patients receiving palbociclib + AI as first-line treatment split into CCI point score of 3 or higher (3+) measure: OS in the full dataset of mBC patients receiving palbociclib + AI as first-line treatment split into CCI point score of 0 measure: OS in the full dataset of mBC patients receiving palbociclib + AI as first-line treatment split into CCI point score of 1 measure: OS in the full dataset of mBC patients receiving palbociclib + AI as first-line treatment split into CCI point score of 2 measure: OS in the full dataset of mBC patients receiving palbociclib + AI as first-line treatment split into CCI point score of 3 or higher (3+) measure: PFS in the full dataset of mBC patients receiving palbociclib + AI as first-line treatment no comorbidity measure: PFS in the full dataset of mBC patients receiving palbociclib + AI as first-line treatment one comorbidity measure: PFS in the full dataset of mBC patients receiving palbociclib + AI as first-line treatment with two or more comorbidities measure: OS in the full dataset of mBC patients receiving palbociclib + AI as first-line treatment no comorbidity measure: OS in the full dataset of mBC patients receiving palbociclib + AI as first-line treatment one comorbidity measure: OS in the full dataset of mBC patients receiving palbociclib + AI as first-line treatment with two or more comorbidities measure: PFS in the full dataset of mBC patients receiving palbociclib + AI as first-line treatment split into type of comorbidity: Cardiac disease measure: PFS in the full dataset of mBC patients receiving palbociclib + AI as first-line treatment split into type of comorbidity: Vascular disease measure: PFS in the full dataset of mBC patients receiving palbociclib + AI as first-line treatment split into type of comorbidity: Metabolic disease measure: PFS in the full dataset of mBC patients receiving palbociclib + AI as first-line treatment split into type of comorbidity: Psychiatric disease measure: PFS in the full dataset of mBC patients receiving palbociclib + AI as first-line treatment split into type of comorbidity: Blood and lymphatic system measure: OS in the full dataset of mBC patients receiving palbociclib + AI as first-line treatment split into type of comorbidity: Cardiac disease measure: OS in the full dataset of mBC patients receiving palbociclib + AI as first-line treatment split into type of comorbidity: Vascular disease measure: OS in the full dataset of mBC patients receiving palbociclib + AI as first-line treatment split into type of comorbidity: Metabolic disease measure: OS in the full dataset of mBC patients receiving palbociclib + AI as first-line treatment split into type of comorbidity: Psychiatric disease measure: OS in the full dataset of mBC patients receiving palbociclib + AI as first-line treatment split into type of comorbidity: Blood and lymphatic system sex: ALL minimumAge: 18 Years stdAges: ADULT stdAges: OLDER_ADULT facility: Copenhagen University Hospital, Rigshospitalet city: Copenhagen zip: 2100 country: Denmark lat: 55.67594 lon: 12.56553 hasResults: False