TABLE 1.

Timeline of the patient’s condition and course of treatment.

Date	Incident description
2021-08	After being diagnosed with right breast invasive ductal carcinoma (stage III, HER2-positive), neoadjuvant chemotherapy was initiated (AC regimen: liposomal doxorubicin + cyclophosphamide).
2021-10-26	Right breast modified radical mastectomy with axillary lymph node dissection.
2021-11-23	Postoperative adjuvant therapy included the AC regimen, followed by the sequential THP regimen (albumin-bound paclitaxel + trastuzumab + pertuzumab), and then the sequential HP regimen (trastuzumab + pertuzumab).
2022-04	The patient discontinued adjuvant therapy on their own.
2023-03-24	First-line treatment with T-DXd was initiated after the development of systemic metastasis combined with PLC.
2024-05-30	Radiological imaging confirmed disease progression (PFS 14.2 months).
2024-06-12	Second-line treatment was initiated with capecitabine, pyrotinib, and nimotuzumab.