Continuous or Intermittent Extension of Adjuvant Pyrotinib for Invasive HER2-positive Breast Cancer

This study is comparing two schedules of a drug called pyrotinib — a targeted therapy for HER2-positive breast cancer — given after completing standard therapy: continuous daily dosing versus an intermittent schedule (taking breaks). The goal is to see which approach is more effective and better tolerated in the long term. **You may be eligible if...** - You are 18 or older - You have confirmed invasive HER2-positive breast cancer - You have completed treatment with trastuzumab or T-DM1 within the past 3 years - You are in good general health (ECOG 0–1) with adequate organ function **You may NOT be eligible if...** - Your cancer has spread to other parts of the body (stage IV) - There is remaining tumor visible after surgery, or your surgical margins are positive - You cannot swallow tablets or have a condition preventing oral drug absorption - You have already received another anti-HER2 tyrosine kinase inhibitor (TKI) - You are pregnant, breastfeeding, or unwilling to use contraception - You have HIV, organ transplant history, or another immunodeficiency Talk to your doctor to see if this trial is right for you.