Response to [90Yttrium-DOTA]-TOC Treatment is Associated with Long-term Survival Benefit in Metastasized Medullary Thyroid Cancer: A Phase II Clinical Trial

Abstract

Abstract Purpose: We aimed to explore the efficacy of 90Yttrium–1,4,7,10-tetra-azacyclododecane N,N′,N″,N-‴-tetraacetic acid (90Y-DOTA)–Tyr3-octreotide (TOC) therapy in advanced medullary thyroid cancer. Experimental Design: In a phase II trial, we investigated the response, survival, and long-term safety profile of systemic [90Y-DOTA]-TOC treatment in metastasized medullary thyroid cancer. Adverse events were assessed according to the criteria of the National Cancer Institute. Survival analyses were done using multiple regression models. Results: Thirty-one patients were enrolled. A median cumulative activity of 12.6 GBq (range, 1.7-29.6 GBq) of [90Y-DOTA]-TOC was administered. Response was found in nine patients (29.0%). Four patients (12.9%) developed hematologic toxicities and seven patients (22.6%) developed renal toxicities. Response to treatment was associated with longer survival from time of diagnosis (hazard ratio, 0.20; 95% confidence interval, 0.05-0.81; P = 0.02) and from time of first [90Y-DOTA]-TOC therapy (hazard ratio, 0.16; 95% confidence interval, 0.04-0.63; P = 0.009). The visual grade of scintigraphic tumor uptake was not associated with treatment response or survival. Conclusions: Response to [90Y-DOTA]-TOC therapy in metastasized medullary thyroid cancer is associated with a long-term survival benefit. Treatment should be considered independently from the result of the pretherapeutic scintigraphy.