deaths (OS)progression or deaths (PFS)RFS/DFS

la/mBC - HR-positive - 1st line (L1) breast cancer - HR positive la/mBC - HR positive la/mBC - HR-positive - 1st line (L1)

versus endocrine therapy
palbociclib plus endocrine therapy vs. endocrine therapy 1 ---
versus letrozole
palbociclib plus letrozole vs. letrozole 2 ---

la/mBC - HR positive - L1 - PIK3CA mutant breast cancer - HR positive la/mBC - HR positive la/mBC - HR-positive - 1st line (L1) la/mBC - HR positive - L1 - PIK3CA mutant