A 42-year-old woman with HER2-positive, hormone-receptor-negative invasive ductal carcinoma (cT2N1M0) receives neoadjuvant chemotherapy with pertuzumab and trastuzumab. Post-mastectomy pathology shows residual invasive disease (ypT1N1). According to current guidelines (KATHERINE trial data), what adjuvant therapy should be administered?
- A Trastuzumab emtansine (T-DM1) for 14 cycles ✓
- B Continue pertuzumab + trastuzumab for 1 year
- C Capecitabine monotherapy for 6 months
- D Lapatinib + capecitabine for 1 year
Explanation
The KATHERINE trial demonstrated that patients with HER2-positive early breast cancer who have residual invasive disease after neoadjuvant HER2-targeted therapy benefit from switching to T-DM1 (trastuzumab emtansine) for 14 cycles as adjuvant therapy, significantly reducing invasive disease-free survival events compared to continuing trastuzumab. T-DM1 combines the HER2-targeting of trastuzumab with the cytotoxic DM1 payload, providing dual-mechanism activity against residual tumor cells. Pertuzumab continuation without changing the backbone is insufficient, and capecitabine alone is used in triple-negative cancer residual disease (CREATE-X trial).
Reference: Bailey & Love's Short Practice of Surgery, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.