In vitro bromodeoxyuridine labelling of squamous cell carcinomas of the oral cavity

Samples of 33 primary and previously untreated squamous cell carcinomas of the oral cavity were labelled by in vitro bromodeoxyuridine (BURD) incubation. Positive cells were visualized by indirect immunofluorescence antibody labelling. The cells were examined by fluorescence microscopy and the labelling index (LI) was calculated. The values ranged from 0 to 23.2% with a median of 2.6%. The LIs of T3 tumors were significantly higher than those of T1 and T2 carcinomas. The LIs of primary tumors showing cervical lymph node metastases at the time of biopsy also had significantly higher values than tumors without evidence of lymph node involvement. The BURD technique seems to represent a promising tool for studying the clinical implications of the proliferative behavior of human tumors.