Outcome Of First-Line Chemotherapy For Anaplastic Thyroid Cancer – A Multicenter Registry Analysis

CONTEXT: Prognosis of anaplastic thyroid cancer (ATC) remains poor. In the absence of immediately actionable molecular alterations, guidelines recommend multimodal therapy including radiotherapy and cytotoxic chemotherapy but optimal regimens are not established. Many centers in Germany have adopted carboplatin-paclitaxel (CP), with or without radiotherapy, as a preferred first-line approach. OBJECTIVE: This study aims to compare the outcome of patients treated first-line with CP±radiotherapy versus other cytotoxic chemotherapy regimens in ATC. DESIGN: Retrospective multicenter registry study in Germany. SETTING AND PATIENTS: 158 adults with histologically confirmed ATC treated with first-line cytotoxic chemotherapy at seven German tertiary centers (2000-2024). MAIN OUTCOME MEASURES: Progression-free survival (PFS) and overall survival (OS) were compared with Kaplan-Meier and log-rank test; Cox proportional hazard model was used to identify risk factors. RESULTS: 97 patients received first-line CP and 61 received other chemotherapy. PFS (102 vs 89 days; log-rank p=0.23) and OS (278 vs 295 days; p=0.50) did not differ between CP and other regimens. Complete response occurred in 13% with CP and 8% with other chemotherapy (p=0.46). In multivariable analyses, age ≥65 years, lymph node metastasis, and distant metastasis were associated with higher mortality risk. Surgery was associated with lower mortality risk. CP was not associated with improved OS. Outcome of second line treatment was not different for chemotherapy vs. kinase inhibition±immunotherapy. CONCLUSION: In this registry study, CP showed no survival benefit in ATC; outcomes depended on disease burden and resectability, underscoring the need for rapid molecular diagnostics. Chemotherapy may serve as a bridging strategy.