IN-VIVO LABELING WITH HALOGENATED PYRIMIDINES OF SQUAMOUS-CELL CARCINOMAS AND ADJACENT NONINVOLVED MUCOSA OF HEAD AND NECK REGION

The frequency and distribution of labelled cells were studied immunohi stochemically in 37 squamous cell carcinomas (SCC) of head and neck af ter in vivo infusion of IdUrd and BrdUrd. Tumours were classified acco rding to their labelling patterns. Low and moderate grade SCC consiste d of tumour islands separated by interstitial tissue. In some tumours labelled cells only appeared near the basal layer while in others prol iferative cells were evenly distributed within the neoplastic island. In anaplastic carcinomas labelled cells were distributed either random ly or around blood vessels (cord structures). While the basal layer in adjacent normal epithelium contained very few labelled cells (LI = 1. 6 +/- 0.2%), the LI of basal cells in tumour islands were much higher than the average LI of the tumour (47.2 +/- 2.8% and 23.8 +/- 1.6%, re spectively). In patients who had received cytotoxic therapy up to two months before the biopsy, the LI in the basal layer of normal epitheli um was 19.0 +/- 3.5%. In sequential biopsies obtained 1-2 weeks after the infusion of IdUrd and BrdUrd some labelled tumour cells were found in necrotic foci and in pearl structures. Additionally, in six tumour s, we found areas of cells labelled with IdUrd alone, even though the IdUrd infusion had been followed by a BrdUrd infusion 1 h later. This is in agreement with the phenomenon of intermittent tumour blood flow described earlier in experimental tumours.