Ki-67 expression in cytologic scrapes from oral squamous cell carcinoma before and after 24 gray radiotherapy--a study on 43 patients.

OBJECTIVE To study the Ki-67 labeling indices in surface scrape smears from patients with oral squamous cell carcinoma before and after 24 Gray radiotherapy. STUDY DESIGN Forty three patients with histologically documented squamous cell carcinoma of the oral cavity were sampled by means of surface scrape smears prior to therapy and after receiving 24 Gray fractionated radiotherapy. These smears were stained for Ki-67 expression using the avidin biotin alkaline phosphatase technique. RESULTS Ki-67 expression was seen in an extremely small number of cells. Only 10 tumors showed positive cells, and the labeling index in them varied from 0.1 % to 0.01 %. After 24 Gray irradiation, no case showed any Ki-67 positive cells. CONCLUSIONS The overall yield of malignant cells in surface smears is low even prior to therapy and their number decreases further after irradiation. This, along with other factors including low concentration of proliferating cells on the surface of the lesion and obscuring inflammatory cells, anucleate squames, bacterial colonies and proteinaceous material could have accounted for the low labeling indices obtained. Radiation induced decline in proliferation has been described previously. The major conclusion, in balance, is that conventional oral scrape cytology may not be the optimal tool for immunocytochemical evaluation of proliferation in oral squamous cell cancer.