YO6 - Neoadjuvant imatinib treatment for giant gastrointestinal stromal tumor of the stomach: Report of two cases

Date 17 December 2016
Event ESMO Asia 2016 Congress
Session Poster lunch
Topics Anti-Cancer Agents & Biologic Therapy
GIST
Presenter Hideaki Karasawa
Authors H. Karasawa, H. Imoto, S. Maeda, T. Aoki, K. Kudoh, J. Sato, T. Takenami, F. Motoi, T. Naitoh, M. Unno
  • Department Of Surgery, Tohoku University Hospital, 9808574 - Sendai/JP

Abstract

Case Summary

Backgrounds:

Gastrointestinal stromal tumor (GIST) is the most common mesenchymal tumor of the gastrointestinal tract. Although the standard treatment for GIST is surgery, a complete resection of the tumor is often difficult to achieve in locally advanced GIST. Neoadjuvant imatinib treatment is recently expected to reduce the risk for an extended or multivisceral resection in patients with a giant GIST. We herein report two cases of giant gastric GIST, which were safely resected following neoadjuvant therapy.

Case 1:

A 72-year-old woman was hospitalized with severe abdominal distension. Computed tomography (CT) revealed 27 x 17 cm tumor in the left upper abdominal cavity. The patient was diagnosed with high risk GIST by EUS-FNA. We performed neoadjuvant therapy with imatinib to achieve reduction of operative risk and functional preservation. After 6 months, CT revealed a reduction in the tumor size, and patient underwent partial gastrectomy and partial resection of the diaphragm. Histologically, most of the tumor cells were replaced by hyalinized collagen and viable cells were scattered only around blood vessels.

Case 2:

A 60-year-old man was also diagnosed with giant gastric GIST (14 x 12cm) and involvements of the spleen and the diaphragm were suspected. Therefore Administration of imatinib was initiated as neoadjuvant therapy. Six months after neoadjuvant therapy, abdominal CT revealed a reduction in tumor size. We judged the tumor resectable and performed partial gastrectomy. Histologically, more than half of the tumor cells were replaced by hyalinized collagen and viable cells were scattered only around blood vessels. The Ki-67 labeling index was less than 1% and no mitotic activity was observed. The postoperative courses were uneventful, and both patients were discharged within two weeks.

Conclusion:

In both cases, the involvements of other organs were initially suspected. However, the tumors were significantly reduced after the neoadjuvant therapy, and surgery was performed safely. Although the evidence from clinical trials of utility and outcome of neoadjuvant therapy with imatinib is limited, it has a potential to become an important therapeutic option for the treatment of giant GIST.