CELL-KINETICS OF HEAD AND NECK CANCERS

We measured the tumor cell proliferative rate in 26 patients with head and neck cancer, 22 of which were squamous cell carcinomas (SCCs). Pa tients received sequential infusions of iododeoxyuridine and bromodeox yuridine, after which the tumor was biopsied and studied, The percenta ge of labeled cells [labeling index (LI)] in well-differentiated SCCs was 20.4 +/- 2.7% (mean +/- SE) and 23.8 +/- 2.1% in moderately differ entiated SCCs (P = 0.135). The LIs of two poorly differentiated SCCs w ere 39.4 and 55.9%. The LI was 2.5% in a high-grade lymphoepithelioma and 24.8% in a malignant lymphoma, In one well-differentiated and one poorly differentiated mucoepidermoid tumor, the LIs were 3.0% and 29.1 %, respectively, S-phase duration time measurements ranged from 5.1-21 .5 h (12.8 +/- 1.5). The calculated potential doubling times ranged fr om 18.8-84.5 h (47.3 +/- 6.7), The duration of G(2) was between 90 and 180 min. To track the fate of labeled cells, in four patients a repea t biopsy was obtained 7-14 days after the iododeoxyuridine/bromodeoxyu ridine infusion. These patients did not receive treatment between the biopsies, Due to the dilution of the label, most labeled cells in the second biopsy demonstrated a ''fragmented'' pattern resulting from rep eated cell divisions, In two patients, however, 25% of cells in the se cond biopsy had undiluted label, suggesting that these cells had not d ivided after incorporating iododeoxyuridine/bromodeoxyuridine, On Day 7 labeled cells migrated to keratinized parts of tumors and to necroti c foci. Thus, the arrest of cell cycle transition, tumor cell differen tiation, and cell death may be major routes of tumor cell loss from th e proliferative compartment. This may explain the difference between v ery short potential doubling times and the actual rate of tumor growth .