Objective: To determine the significance of the TLE-1 expression in GISTs, and evaluate the predictive value of TLE-1 expression in patient survival.
Study design: An observational study. Place and Duration of the Study: The archives Department of Pathology, Başkent University, Adana, Turkey, between 2010 and 2021.
Methodology: Fifty patients diagnosed with GIST were included in the study. The diagnosis of GIST was confirmed in all tumours with an immunohistochemistry panel comprising CD117, DOG1, CD34, SMA, S100, and Ki67. The expression of TLE-1 in all tumours was evaluated. Positive and negative predictive values between pathological parameters findings were evaluated and differences between methods were evaluated using 2019 Medcalc. The correlations between the immunoscore value and prognostic parameters were analysed using correlation chi-square test.
Results: Among 50 patients, 31(62%) were males, and 19 (38%) were females. The mean age was 59±13.5 (24-78) years. The tumour grade showed a significant positive correlation with the number of mitoses, tumour size, presence of metastases, and the Ki67 proliferation index. A significant positive correlation was observed between CD117 and DOG-1 immunostaining (r= 0.64, p<0.001). Ki67 index was found to be directly proportional to number of mitoses, tumour size, and DOG-1 expression. Although TLE-1 showed a significant relationship with tumour type (p=0.034), it did not demonstrate a statistically significant relationship with mitosis, tumour grade, or survival. Compared to the spindle cell type, mixed and epithelioid type tumours were immunostained with TLE-1 more frequently and intensely.
Conclusion: While GISTs showed a close relationship with classical prognostic factors, TLE-1 tumour expression was not associated with any prognostic parameter other than the tumour type. Moreover, using an immunostaining panel that includes other sarcomas in the differential diagnosis, especially in tumours with mixed or epithelioid patterns. Molecular genetic confirmation will help the patient in terms of accurate diagnosis and appropriate treatment in difficult cases.
Key words: Gastrointestinal stromal tumour, TLE-1, Prognosis, Survival.