Clinical Outcomes and Treatment-Related Complications in Triple-Negative Breast Cancer: A Review of 24 Case Reports from 2020 to 2025.

Triple-negative breast cancer (TNBC) is clinically heterogeneous, and selected patients experience rare complications, unusual responses, or biomarker-discordant treatment trajectories that are not fully represented in aggregate trial evidence. This review aims to synthesize published case-report evidence on clinical outcomes and treatment-related complications in TNBC, with an emphasis on host vulnerability, tumor biology, biomarker-guided treatment, and therapy-associated toxicity. A descriptive review of PubMed-indexed case reports was performed for records published from January 1, 2020, to December 31, 2025. Two reviewers independently screened records, extracted data, and appraised the reporting quality using the CARE domains. Results were synthesized narratively without meta-analysis. Seventy-one records were screened, and 24 case reports were included. All patients were female, with a median age of 45 years (range 28-87 years). The cases consisted of 11 with metastatic or advanced disease, 10 with early or localized disease, 1 with a local recurrence, and 2 with unclear disease settings. Actionable or resistance-informative biomarker signals were described in 12 cases, and biomarker-matched therapy was reported in 11. Immunotherapy was used in 9 cases. Serious or clinically significant complications were reported in 10 cases, including two fatal treatment-related events. Favorable outcomes were reported in 17 cases, but these selected reports cannot be used to estimate response rates, survival, or the incidence of toxicity. TNBC case reports provide clinically instructive, hypothesis-generating evidence on rare toxicities, biomarker-guided treatment decisions, and individualized risk assessment.