Metastatic gastrointestinal stromal tumor: A regional cancer center experience of 44 cases

Background: Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms of the gastrointestinal tract. Historically, a poor prognosis for metastatic disease has been reported with systemic chemotherapy. Significant advances have been made in the last decade, since the introduction of different tyrosine kinase inhibitors (TKIs). Unfortunately, even though the TKIs have been used for a long time, there are very few published data of the experience of TKI therapy in metastatic GIST from India. Materials and Methods: Patients diagnosed with metastatic GIST from January 2005 to October 2016 at our center, who received first-line therapy with imatinib 400 mg/day, were reviewed retrospectively. Patients' profile, response to treatment, toxicity of TKI therapy, time to progression, and survival were evaluated. Results: Of the 44 metastatic GIST patients, 23 (52.2%) were males. Median age at diagnosis was 48 years. The most common presenting symptom was an abdominal pain (52%), followed by weight loss (23%). Most frequently affected metastatic site was liver (57%), followed by peritoneum (16%), and lungs (4.5%). Metastases to both liver and peritoneum were found in 10 patients (22.5%). All patients were initially treated with imatinib at a dose of 400 mg/day. Disease stabilization was documented in 21 cases (48%), and 13 patients (29%) achieved a partial response. TKI therapy was well-tolerated in most cases. Median progression-free survival (PFS) was 26 months, and estimated median survival was 48 months. Patients with lung metastases have a significantly inferior median PFS and overall survival, in comparison to patients with other metastatic sites (P < 0.05). Conclusions: Imatinib therapy was well tolerated and induced a sustained clinical benefit in more than half of the patients with metastatic GIST. Lung metastases seemed to be a poor prognostic factor in this patient population.