Experiences with gastrointestinal stromal tumour at the Oncology Hospital Siglo XXI IMSS

Abstract

9048 Background: The gastrointestinal stromal tumours (GIST) are neoplasm of the mesenchymal; their cells show similar characteristics to the interstitial cells of Cajal and are characterized by the expresion of CD117, the antigen to a specific transmembrane epitope of KIT; mutations of KIT have been demonstrated in more than 92% of GIST and this has a fundamental role in the development of this tumours. Imatinib mesylate is a type of tyrosine kinase inhibitor that selectively inhibits various tyrosine kinases including ABL, BCR/ABL, KIT and PDGF receptors. Methods: At the Oncology Hospital “Siglo XXI” seven patients were studied from January to September 2004 with a confirmed diagnostic by histopathology and immunohistochemical of stromal tumour. The patients were treated with Imatinib mesylate at dosis of 400 mg/per day. Results: With an average age of 59 years and with female sex predominance (6:1), the tumour was presented in the following areas: small intestine 2; rectum 2; gastric 1; mesenteric 1, papilla of Vater 1. From those, 4 were recurrent, 2 with metastatic disease and 1 with inoperable disease. With an average follow up of 9 months (5–10 months), from 7 patients, one had a complete response (14.28%) and two with partial response (28.57%), two with stable disease (28.57%) and with a overall response of 71.99% . Progression in two patients (28.57%). The treatment is well tolerated with gastrointestinal toxicity grade 1 for nausea. Conclusions: The imatinib mesylate achieved to induce objective responses in more than 50% of the patients with inoperable and/or metastatic disease, even though the follow up is still not long. Similar results are found in the literature. The KIT inhibition is a promising treatment with patients with GIST, whom are usually resistant to chemotherapy. No significant financial relationships to disclose.