Application of in vitro bromodeoxyuridine labeling of oral cancers

We used immunohistochemical methods to investigate whether in vitro labeling with bromodeoxyuridine (BrdU) of oral cancer tissues is useful in pathological diagnosis. BrdU-positive cells were found around the basal region of the epithelium in normal oral mucosa, in a papilloma specimen and in tissue with moderate dysplasia. The labeling rates (percentage of BrdU-positive cells, LR) for these cases were 1.2%, 6.9% and 7.5%, respectively. In well-differentiated carcinoma, more layers of BrdU positive cells were observed from the basal layer toward the surface. The LR in this region was 13.9-17.0%. In vitro BrdU labeling of oral tumors may be useful in pathological diagnosis, since the LR is lowest in normal tissues, higher in benign tumors, and highest in malignant tumor tissues.