The Role of Imatinib Mesylate in Adjuvant Therapy of Extra-abdominal Desmoid Tumors

Background: Extra-abdominal desmoid tumors are rare neoplasms with variable biological behavior. The mainstay of treatment is surgery. Complementary treatment with tyrosine-kinase receptor inhibitor drugs, particularly imatinib mesylate, has been reported in the literature. The purpose of this study was to determine the possible presence of tyrosine-kinase receptors in extra-abdominal desmoid tumors as a marker for imatinib mesylate therapy. Patients and Methods: From 1999 to 2004, immunohistochemical methods were carried-out in 14 patients with histologically confirmed extra-abdominal desmoid tumors to determine c-KIT positivity (existence of tyrosine-kinase receptors and PDGFRA and PDGFRB). Results: All desmoid tumors were c-KIT negative, which demonstrates absence of tyrosine-kinase receptors. Conclusion: The histological c-KIT markup is an easy and reliable method that can detect whether a desmoid tumor is sensitive to additional treatment with a tyrosine-kinase receptor inhibitor. Molecular biological analysis for the identification of KIT and PDGFR mutation should be performed before imatinib mesylate is included in any treatment protocol.