Study variables
death, neutropenia, breast cancer, advanced/metastatic disease, palbociclib initiation, breast cancer disease
DISEASE PROGRESSION, RECURRENCE, NEUTROPENIA, FEBRILE NEUTROPENIA, BREAST CANCER, ADVERSE EVENTS, DISEASE, METASTASES
For the present analysis we evaluated the following outcomes: clinicopathological characteristics (patient characteristics [age, sex, ethnicity, menopausal status, comorbidities]; breast cancer disease characteristics [time since initial diagnosis, recurrence, stage at time of treatment, sites of metastases, oestrogen-receptor status, progesterone-receptor status, HER2 status, and disease-free interval]; and prior breast cancer treatments); palbociclib treatment patterns (dosage, dose reductions, dosing interruptions and treatment discontinuations) and treatment duration; clinical outcomes up to 24-months post-palbociclib initiation (OS defined as the time from the date of palbociclib initiation until death from any cause as assessed by the individual centres [clinic visit, general practitioner records]; PFS defined as the time from the date of palbociclib initiation to the date of first documented disease progression or death as assessed during a clinic visit [radiological assessments]; best overall response [complete response (CR), partial response (PR), stable disease, progressive disease] as assessed by the treating physician [radiological assessments]; time to best response and time to CR/PR at 1-, 2-years post-initiation); and selected adverse events during the first 12 months post-palbociclib initiation (neutropenia, febrile neutropenia, and gastro-intestinal toxicity).During the evaluation of patients’ breast cancer treatment history, it became apparent that not all patients received palbociclib in the first line; therefore, patients were grouped based on the treatment line as well as defined according to breast cancer treatment history for the purpose of this analysis as follows: (1) First line: patients initiated on palbociclib in combination with an AI with no prior treatment (2) First-line palbociclib added to letrozole: letrozole started >3 months prior to initiation of palbociclib. (3) Second or subsequent line: patients initiated palbociclib in combination with ET after at least one other treatment for advanced/metastatic disease.