Abstract
BACKGROUND: Anaplastic thyroid carcinoma (ATC) is a rare and highly aggressive malignancy historically associated with a poor prognosis and a median survival of only 3.16 months. However, recent advances in molecular profiling and immunotherapy are improving outcomes. CASE PRESENTATION: We report the case of a 68-year-old man diagnosed with stage IVC ATC who achieved sustained disease stabilisation and long-term survival. Initial treatment with chemotherapy and radiotherapy led to partial remission of the primary tumour, although there was progression of metastatic disease. The patient was subsequently enrolled in a clinical trial investigating an anti-PD-L1 antibody with positive test results, followed by treatment with pembrolizumab. The latter resulted in nearly 11 years of disease control without significant adverse effects, an exceptional outcome in the context of ATC. CONCLUSION: This case underscores the transformative potential of immunotherapy in the management of advanced ATC and highlights the importance of continued research into combinatorial therapeutic strategies and predictive biomarkers to optimise treatment outcomes.