CELL-KINETICS AND TUMOR-REGRESSION DURING RADIOTHERAPY IN HEAD AND NECK SQUAMOUS-CELL CARCINOMAS

Head and neck squamous-cell carcinoma (HN-SCC) patient management is m ainly based on TNM classification and needs be improved by considering other potentially useful prognostic factors. We examined the pre-radi otherapy tumor potential doubling time (T-pot) evaluated after in vivo infusion of bromodeoxyuridine and flow-cytometric analysis and the ea rly clinical tumor regression after 40 Gy (40 Gy-TR). T-pot values and clinical 40 Gy-TR classes (minor and major) were available for 82 HN- SCC patients. Radiation therapy completion was done either with I dose per day (conventional regimen) or 2 doses per day (accelerated regime n). Local control was also available for follow-up times above 4 years . We found that major 40 Gy-TR was strongly correlated with fast tumor growth, characterized by T-pot values below 5 days, and that patients with major 40 Gy-TR showed better local control than those with minor 40 Gy-TR, independently from the radiotherapy regimen type. We also f ound that treatment completion with accelerated radiotherapy gave bett er local control for patients with major 40 Gy-TR and fast tumor growt h than conventional radiotherapy. Multivariate analysis, performed on all patients, assigned an independent prognostic value to T-pot, tumor classification and 40 Gy-TR. (C) 1996 Wiley-Liss, Inc.