STROMAL c- kit EXPRESSION IN ORAL SQUAMOUS CELL CARCINOMA

Objective: To evaluate the expression of c-kit (CD-117) in stromal cells associated with oral squamous cell carcinoma (SCC), and to investigate the possible correlation with clinico-pathological features and outcome. Materials and Methods: The study group consisted of 17 patients with primary SCC of the tongue treated between 1990-2004, and a control group of 8 patients with irritation fibroma of the tongue.On formalin-fixed, paraffin-embedded tissue sections, immunohystochemistry using a c-kit monoclonal antibody (Dako, Hamburg, Germany,1:100) with microwave pretreatment. The number of CD-117 positive cells and the total number of spindle cells were counted in 5 HPFs at the tumor front in the study group, and in 5 sub-epithelial fields in the control group. Results: 34.8 % of patients were T1, 64.7% T2 and 8.7% T3. All patients were treated by partial glossectomy and neck dissection, with postoperative radiation therapy in 5 patients. Follow-up period ranged between 13-130 months, (mean 41.1 months). In 10 patients loco-regional control failed within 24 months. At the end of the follow-up period, 9 patients (52.9%) were dead of disease and 7 patients (41.2%) had no evidence of disease. Results: A mean of 56.6% of the tumor-associated spindle cells in the study group were CD-117 positive- 42.6% in the group which was free of disease, 64% in the group with loco-regional control failure. The SCC tumor cells did not express CD-117. In the control group, 28.2% of the spindle cells were positive. Conclusion: CD-117 is upregulated in tumor-associated stromal cells, more in tumors with failure of locoregional control than in those with no evidence of disease after treatment. The significance of the c-kit oncogene product in the tumor-associated stroma, as a potential prognostic marker requires further investigation.