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The Scientific World Journal
Volume 2014, Article ID 368947, 6 pages
http://dx.doi.org/10.1155/2014/368947
Clinical Study

Dynamic Metabolic Changes during the First 3 Months after 90Y-Ibritumomab Tiuxetan Radioimmunotherapy

1Department of Radiology, Graduate School of Medicine, The University of Tokyo, 3-1 Hongo 7-Chome, Bunkyo-ku, Tokyo 113-8655, Japan
2Department of Hematology and Oncology, Graduate School of Medicine, The University of Tokyo, 3-1 Hongo 7-Chome, Bunkyo-ku, Tokyo 113-8655, Japan

Received 31 January 2014; Accepted 3 June 2014; Published 19 June 2014

Academic Editor: Akihiro Takano

Copyright © 2014 Miwako Takahashi et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Objective. To elucidate the time course of tumor metabolism during the first 3 months after 90Y-ibritumomab tiuxetan radioimmunotherapy (RIT) in patients with refractory malignant lymphoma. Materials and Methods. Seven patients with recurrent follicular lymphoma underwent FDG-PET imaging before and after 1-, 4-, and 12-week RIT with 90Y-ibritumomab tiuxetan. Tumor metabolic activity on FDG-PET scans was assessed as the maximum standard uptake value (SUVmax). Results. Decrease in metabolism was detected 1 week after RIT. In the most decreased lesion, SUVmax decreased to 20% of the baseline value during the first week. Most lesions continued to decrease for up to 4 weeks. Some lesions showed increased metabolism from 4 to 12 weeks, while the level of FDG accumulations at 12 weeks was still lower than the baseline. Conclusions. Tumor response to RIT could be observed as early as 1 week after the administration of RIT. After tumor activity decreases, the metabolism may increase at least between 4 and 12 weeks. It suggests that the metabolic changes should be carefully evaluated during this period.