A comparative study of histological grade and expression of Ki67 protein in oral squamous cell carcinoma in young and old patients

Background: Oral squamous cell carcinoma (SCC) is the most common cancer of oral region. The characteristic feature of SCC is invasion of dysplastic epithelium into the connective tissue. Oral SCC is more common in old patients. It is believed that etiology and pathogenesis of SCC in young patients differ from old patients and it is related to different molecular mechanism. In this study, histopathologic differentiation and proliferation activity (by Ki67) in oral SCC lesions of young patient (<40 years) and old patients (>50 years) have been compared. Materials and Methods: In a cohort study, Formalin Fixed and paraffin‑embedded tissue sections of 20 oral SCC of young patients and 20 oral SCC of old patients were stained by H and E and immunohistochemically by biotin‑streptavidin method. They were observed by two pathologists. Histological grade and Ki67 labeling index (LI) were determined. Data were analyzed by t‑test and Mann‑Whitney. Results: In cases of oral SCC in young patients, 80% were grade I and 20% were grade II and Ki67 LI was 21/5% in this age group. In cases of oral SCC in old patients, 75% were grade I and 25% were grade II and Ki67 LI was 21/6% in this age group. Conclusion: Histological and immunohistochemical evidence of this study show that oral SCC of young patients and oral SCC lesions of old patients didn’t show any differences in histopathological differention and proliferative activity.