Gastrointestinal Stromal Tumors (GIST): Is the Incidence rising in India? —A Hospital Based Analysis

Context: Gastrointestinal stromal tumours (GISTs) are rare tumours of the gastrointestinal tract (GI) but they are the most common amongst the mesenchymal tumours. However, there are very few published articles on patients with the diagnoses of GISTs from the Indian subcontinent and particularly from the eastern part of India. Also we noted an increased number of patients with the diagnosis of GISTs in our clinical practice compared to the past decade and have observed an increased incidence of tumours arising from the small bowel and large bowel compared to the stomach. Aims: To study the incidence of symptomatic GISTs, the demographic details, clinical presentations, the histopathological and immunohistochemistry features and survival of the patients and response of these tumours to imatinib therapy. Settings and Design: A retrospective study based on hospital registry conducted in the Departments of Radiotherapy and General Surgery, IPGME&R- SSKM Hospital, Kolkata and NRSMCH, Kolkata. Methods & Material: Cross sectional imaging and endoscopic evaluations were used to diagnose the tumours. Tumor categorization required microscopic and immunohistochemistry studies for c-Kit, DOG-1 and other tumor markers. High risk group tumours were treated with imatinib 400 mg/day for 3 years duration. Statistical Analysis:Incidence of GISTs was analyzed using Pearson Chi-square test and Survival was analyzed using Kaplan-Meier survival curve and Pearson Chi-square test. Results: Incidence of GISTs in 2010-2011 was 0.37% whereas in 2018-2019 it was 2.48% with 85% increase, p value of <0.001. The commonest tumor location was in the small bowel (40.7%), followed by stomach (25.4%) and colo-rectum (10.2%). Mean duration of imatinib therapy was 19.33 months with 84% overall survival. Estimated three-year OS (overall survival) was 73.6%. Estimated mean OS was 66±5.39 months with 95% CI 55.6-76.7. Mean survival of patients with metastatic disease on imatinib therapy was 16.88 months with p=0.000. Primary response to imatinib therapy was observed in 93.87% (43/46) patients. Patients developing disease progression on imatinib were treated with Sunitinib and they demonstrated partial response. Conclusion: We have documented an increased incidence of gastrointestinal stromal tumours and there is increased proportion of small bowel and colorectal tumours compared to gastric tumours. Keywords: Gastrointestinal Stromal Tumours, Incidence, cKIT, DOG-1, Imatinib