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Case Reports in Oncological Medicine
Volume 2011, Article ID 638794, 5 pages
Case Report

18FDG-PET at 1-Month Intervals Is a Better Predictive Marker for GISTs That Are Difficult to Be Diagnosed Histopathologically: A Case Report

1Department of Clinical Oncology, Akita University Graduate School of Medicine, 1-1-1 Hondo, Akita 010-8543, Japan
2Division of Clinical Pathology, Faculty of Medicine, Akita University, 1-1-1 Hondo, Akita 010-8543, Japan
3Department of Gastroenterological Surgery, Akita University, 1-1-1 Hondo, Akita 010-8543, Japan
4Department of Gastroenterology and Neurology, Akita University, 1-1-1 Hondo, Akita 010-8543, Japan
5Department of Radiology, Akita University, 1-1-1 Hondo, Akita 010-8543, Japan

Received 3 July 2011; Accepted 3 August 2011

Academic Editors: S. B. Chichareon and A. Goodman

Copyright © 2011 Kazunori Otsuka 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.


Imatinib mesylate is a tyrosine kinase inhibitor of c-KIT and PDGFRA. Imatinib mesylate is an effective drug that can be used as a first-choice agent for treatment of GISTs. Prior to treatment, molecular diagnosis of c-KIT or PDGFRA is necessary; however, in some types of GISTs, it is impossible to obtain a sufficient amount of specimen for diagnosis. An inoperable or marginally resectable GIST in a 79-year-old female was difficult to be diagnosed at a molecular pathological level, and hence, exploratory treatment was initiated using imatinib combined with 18FDG-PET evaluation at 1-month intervals. PET imaging indicated a positive response, and so we continued imatinib treatment in an NAC setting for 4 months. As a result, curative resection of the entire tumor was successfully performed with organ preservation and minimally invasive surgery. 18FDG-PET evaluation at 1-month intervals is beneficial for GISTs that are difficult to be diagnosed histopathologically.