PIK3CA and breast cancer: We further adjusted stepwise, the PAM50 subtype (Model 3), risk stratification (Model 4), DNAm age (Model 5), and gene mutations (GATA3, PIK3CA, MLL3, CDH1, TP53, and MAP3K1) (Model 6‐11), it turned out that the strength of the association between breast cancer recurrence and young patients over middle‐aged patients was gradually weakened.