Viscum Album for TNBC on Adjuvant Pembrolizumab

Inclusion Criteria: 1. Adults aged 19 years or older 2. Histologically confirmed diagnosis of triple-negative breast cancer 3. ECOG Performance Status of 0 or 1 4. Completed surgery and radiotherapy for localized disease, and either (a) requires adjuvant chemotherapy including immune checkpoint inhibitors, or (b) has initiated such therapy within 3 cycles 5. Laboratory values meeting the following criteria: Absolute Neutrophil Count (ANC) ≥ 1,500/μL Platelet count (PLT) ≥ 100,000/μL Hemoglobin (Hb) ≥ 9.0 g/dL Albumin ≥ 3.0 g/dL Acceptable levels of creatinine, total bilirubin, AST, and ALT ≤ 3 × upper limit of normal (ULN) 6. Able to understand the study information and voluntarily provide written informed consent Exclusion Criteria: 1. Presence of distant metastasis 2. Uncontrolled pleural effusion, ascites, or pericardial effusion 3. Other non-cancer comorbidities (e.g., dementia, cerebrovascular disease, end-stage renal disease) that are expected to significantly impair physical function 4. Pregnant or breastfeeding women 5. Estimated life expectancy of less than 3 months, making adequate follow-up unlikely 6. Any other medical condition that may interfere with study results or any situation in which, in the investigator's judgment, participation is not appropriate