P-0133 Long Term Follow up of Managing Patients with Metastatic Gastrointestinal Stromal Tumour with Imatinib Mesylate at an Indian Centre

Abstract

ABSTRACT Introduction Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms of the gastrointestinal tract. Most commonly originate in the stomach and small intestine. One third of high risk, malignant GIST have poor prognosis after surgery. The most common site of the metastasis is the liver. Imatinib mesylate is a KIT tyrosine kinase inhibitor with effect on metastatic GIST. We report our long term follow up in patients with metastatic GIST receiving Imatinib. Methods Retrospective analysis of patients diagnosed with metastatic GIST from 2004 to 2011 at our centre, who received Imatinib mesylate at a dose of 400 mg per day over 6 months. Patients' profile, tumor response, side effects, time to progression and survival were evaluated. Results Eight C-Kit or CD 117 positive GIST patients were enrolled at our centre, there were 6 (75%) male and 2 (25%) female. Median age of patients was 64 years (range 38 to 86 years). Four GISTs originated from stomach, 2 from Rectum, 1 each from jejunum & ileum. Most common symptoms were anaemia and pain abdomen. Liver metastasis in 5, lung in 2 and breast in 1. Four patients underwent surgical treatment. Majority of them (75%) were of the high-risk malignant category. Histologically, the majority had a pure spindle cell morphology. All of them started on Imatinib, all had palliative benefit, half had significant shrinkage of tumour mass. Most common side effects were periorbital oedema, muscle cramps, and diarrhea. Follow-up of 4 cases, treated with adjuvant Imatinib for 6 months after surgical resection showed stable disease for periods from 5 to 8 years. However, 2 cases treated with Imatinib for longer than 6 months had problems due to recurrent, metastatic, or inoperable disease. The long-term Imatinib mesylate treatment was safe and well tolerated. At a median follow-up of 38 months (range 13 to 96 months), the 5 year survival rate was 88%. Conclusion Adjuvant therapy Imatinib should be used for patients with high-risk advanced GISTs. The Imatinib mesylate treatment can prolong the survival of the patients who have metastatic GIST before or after radical surgery without toxicity of chemotherapy.