Trial Outcomes & Findings for Real-world Treatment Patterns of Endocrine Based Therapy Among Patients With Hormone Receptor-positive/Human Epidermal Growth Factor Receptor-2-negative (HR+/HER2-) Advanced Breast Cancer: An Analysis of Administrative Claims Data in Japan (NCT NCT05153187)

Data from Japanese participants diagnosed with breast cancer and whose data were entered into Medical Data Vision (MDV) database from Apr-2008 and had at least one record of palbociclib treatment from 15-Dec-2017 were included in this study. Data was collected from 15-Dec-2017 (launch date of palbociclib in Japan) until 30-Jun-2021. Available retrospective data was evaluated in approximately 22 months (from 31-Aug-2019 to 30-Jun-2021) in this observational study as per its objective.

Race and Ethnicity were not collected from any participant.

Percentage of participants according to number of blood tests (0, 1, 2, 3, 4 and \>=5) at 1 to 4 weeks after administration of palbociclib is reported in this outcome measure.

Percentage of participants according to number of blood tests (0, 1, 2, 3, 4 and \>=5) at 5 to 8 weeks after administration of palbociclib is reported in this outcome measure.

Percentage of participants according to number of blood tests (0, 1, 2, 3, 4 and \>=5) at 9 to 12 weeks after administration of palbociclib is reported in this outcome measure.

Percentage of participants according to number of blood tests (0, 1, 2, 3, 4 and \>=5) at 13 to 16 weeks after administration of palbociclib is reported in this outcome measure.

Percentage of participants according to number of blood tests (0, 1, 2, 3, 4 and \>=5) at 17 to 20 weeks after administration of palbociclib is reported in this outcome measure.

Time to treatment failure of palbociclib was defined as time from the date of first palbociclib prescription to the date of lost to follow-up or to the date of the next line of therapy, defined as the end of palbociclib treatment. Time to treatment failure of palbociclib was censored at participant disenrollment or end of study period.

Number of participants according to regimen of first subsequent therapy after end of palbociclib at first line and second line are reported in this outcome measure. The regimen was defined as any breast cancer treatment(s) received within 30 days of earlier treatment initiation. Only regimens used by \>=3 participants in participants treated with palbociclib in the first or second line settings were reported. One participant may be included in more than one regimen.

Time to treatment failure of subsequent therapy after palbociclib was defined as time from the date of first next line of therapy after end of palbociclib treatment to the date of lost to follow-up or to the date of the second next line of therapy. Time to treatment failure was censored at participant disenrollment or end of study period.

BMI was calculated using the formula: BMI=(weight)/(height/100)\^2.

Charlson Comorbidity Index predicts the ten-year mortality for a participant who may have a range of comorbid conditions. 17 comorbidities were assessed with associated weights from 1 to 6, based on the adjusted risk of mortality. The total score is derived by summing up the weights of comorbid conditions presented. The minimum score value is 0 and maximum is 37. A higher score means a greater mortality risk.

Index year was considered as the year corresponding to the start date of the first palbociclib line. Number of participants according to index year (2017, 2018, 2019, 2020, 2021) are reported in this outcome measure.

One participant may be included in more than one breast cancer treatment.

Number of participants according to the type of endocrine therapy (fulvestrant, letrozole, exemestane, anastrozole, tamoxifen, toremifen and other) combined with palbociclib at first line, second line and third line is reported in this outcome measure. "Other" included participants prescribed \>=1 endocrine therapies and those prescribed medroxyprogesterone.