Analysis of clinicopathological and immunephenotyphic features in our gastrointestinal stromal tumors series

Gastrointestinal stromal tumours (GISTs) are the most common mesenchymal tumours of the gastrointestinal tract. They account for %1-3 of all gastrointestinal tumours. GISTs are a distinct group of tumours, and because of the significant risk of late recurrence in GISTs, each case should be assessed for risk rather than for benign-malignant differentiation, and all cases with GISTs should be followed up regularly, even if they have a low risk of malignancy. The risk of recurrence and metastasis of GISTs varies according to parameters such as tumour location, size and mitotic count. NIH criteria and AFIP criteria are the most commonly used risk scoring systems. In our study, 45 cases with gastrointestinal stromal tumours diagnosed between February 2009 and November 2023 and registered in the archive of Tokat Gaziosmanpaşa University Faculty of Medicine, Department of Pathology, were included in the study. The relationship between clinicopathological parameters, immunohistochemical staining characteristics, NIH risk score, AFIP risk score and survival was analysed. In our study, the parameters that significantly changed the median survival time in the survival analyses were tumour location, tumour size, tumour cell type, synchronous or metachronous additional malignancy status (Log Rank p<0,05). In the analyses, the AFIP risk score was correlated with the NIH risk score, CD34 immunohistochemical staining, and S100 immunohistochemical staining status, and the relationship between them was statistically significant (p<0,001, p=0,029, p=0,023, respectively). The NIH risk score was correlated with tumour necrosis, lymphovascular invasion, surgical margin status and Ki-67 proliferation index, and the relationship between them was statistically significant (p=0,003, p=0,049, p=0,040, p=0,048, respectively). In conclusion, macroscopic tumour characteristics (tumour diameter, presence of necrosis, capsular integrity), microscopic tumour characteristics (mitosis, tumour cell type, cellularity, cytological atypia, tumour necrosis, lymphovascular invasion, treatment-related changes) and immunohistochemical staining conditions should be defined in detail since they are important in both differential diagnosis and prognosis. Since the number of cases was limited, it was concluded that clinicopathological studies in larger series would allow the data obtained in this study to become more meaningful. Keywords: Gastrointestinal stromal tumour, NIH risk score, AFIP risk score