Overall survival: time from the date of treatment initiation with ribociclib until death due to any cause; if a patient is not known to have died, then the OS will be censored at the latest date the patient was known to be alive.

Prognostic factors influencing the OS and PFS will be listed

Proportion of patients with adjuvant treatment and type of treatment to be collected

Proportion of patients treated with chemotherapy/ET/targeted therapy and type of local treatment to be collected

Proportion of patients by menopausal status (pre-/perimenopausal patients versus postmenopausal patients)

Proportion of de novo metastatic patients, 1L, 2L and >2L at ribociclib initiation to be collected

Proportion of patients with complete response (CR)/partial response (PR)/stable disease (SD)/progressive disease (PD)/unknown to be collected

Overall response rate, defined as the proportion of patients with best overall response or complete response (CR) or partial response (PR) according to RECIST 1.1.

Progression free survival (PFS): time from the date of treatment initiation with ribociclib to the date of the first documented disease progression or death due to any cause, whichever occurs first; if a patient has not had an event, the PFS will be censored at the date of the last adequate tumor assessment (RECIST 1.1).

Progression free survival (PFS): time from the date of treatment initiation with ribociclib to the date of the first documented disease progression or death due to any cause, whichever occurs first; if a patient has not had an event, the PFS will be censored at the date of the last adequate tumor assessment (RECIST 1.1).

Overall survival: time from the date of treatment initiation with ribociclib until death due to any cause; if a patient is not known to have died, then the OS will be censored at the latest date the patient was known to be alive.

Overall survival: time from the date of treatment initiation with ribociclib until death due to any cause; if a patient is not known to have died, then the OS will be censored at the latest date the patient was known to be alive.

In the subgroup of patients with visceral metastasis: proportion of patients with complete response (CR)/partial response (PR)/stable disease (SD)/progressive disease (PD)/unknown to be collected

Sequential progression free survival: time from the date of treatment initiation with ribociclib to the date of the second and subsequent documented progression or death due to any cause, whichever occurs first.

Time to chemotherapy since ribociclib initiation to be collected

Proportion of patients with ribociclib dose adjustment after treatment initiation; adjustment type (dose modifications/interruptions during treatment) and reason(s) for dose modifications/interruptions).

Treatment exposure to ribociclib: time from treatment initiation to treatment discontinuation.

Treatment discontinuation: permanent cessation of the treatment received, for any reason.

In the subgroup of oligometastatic patients at inclusion: proportion of patients treated with local treatment and treatment outcome to be collected

Proportion of visits in the site versus proportion of remote visits to be collected

Proportion of patients with at least one hospitalization to be collected

EQ-5D-5L is a standardized participant completed questionnaire that measures health-related quality of life and translates that score into an index value or utility score. EQ-5D-5L consists of two components: a health state profile and an optional visual analogue scale (VAS). EQ-5D health state profile is comprised of 5 dimensions: mobility, self-care, usual activities, pain/discomfort and anxiety/depression. Each dimension has 5 levels: 1= no problems, 2= slight problems, 3=moderate problems, 4= severe problems, and 5= extreme problems. Higher scores indicated greater levels of problems across each of the five dimensions.