Proliferating cell nuclear antigen (PCNA) expression in oral squamous cell carcinomas.

Proliferating cell nuclear antigen (PCNA) is a nuclear protein synthesized in the late G1 and S phase of the cell cycle which can be detected immunohistochemically in paraffin-embedded tissue as a useful marker for the proliferating fraction of cells in tissue specimens. Thirty-eight cases of oral squamous cell carcinoma were studied in groups according to clinical staging and histological grading (UICC system), these included 5 cases of T1, 13 cases of T2, and 20 cases of T3, and 19 cases of G1, 12 cases of G2, and 7 cases of G3. The mean percentage of PCNA positively stained tumor cells in this series was 29.2. The mean percentages of PCNA-positive cells in each stage and grade were: T1 (13.7%), T2 (24.4%), and T3 (34.3%); G1 (30.5%), G2 (24.8%), and G3 (33.2%). The results indicate that the percentage of PCNA positively stained tumor cells in oral squamous cell carcinoma was significantly greater when tumor size was larger than 2 cm (T1 versus T2/T3). However, there was no significant difference between T2 and T3. There was no correlation between the number of PCNA-stained tumor cells and histological grade.