PREDICTIVE VALUE OF POTENTIAL DOUBLING TIME IN HEAD AND NECK-CANCER PATIENTS TREATED BY CONVENTIONAL RADIOTHERAPY

Purpose: The goal of this study was to investigate the clinical utilit y of pretreatment measurements of tumor cell kinetics to predict the o utcome of patients with squamous cell carcinoma of the head and neck r eceiving conventional radiotherapy. Methods and Materials: All patient s received between 64 and 70 Gy as 2 Gy fractions, five fractions per week, Cell kinetics were assayed rapidly and quantitatively using flow cytometric evaluation of iododeoxyuridine (IdUrd) incorporation, in v ivo, from a biopsy removed several hours after the administration of t he DNA precursor to the patient prior to the start of treatment, Resul ts: The measured proliferation parameters were not related. to the cli nicopathological features of the tumors, emphasizing the independent n ature of these parameters, In univariate analysis, nodal involvement w as the most important clinical feature of the tumors related to local control followed by T-pot, DNA aneuploidy, and attainment of complete regression at 6 weeks, Of these only T-pot and nodal status maintained significance in multivariate analysis, with respect to loco-regional control, In subgroup analysis, T-pot was able to stratify patients int o high or low rate of loco-regional control in node negative patients, in aneuploid tumors and in patients who did achieve complete regressi on at 6 weeks, For cause specific survival, N-stage was the only param eter that significantly discriminated the prognosis in these patients, Conclusions: The conclusion of this study is that T-pot provides clin ically important information that can predict patients with a low prob ability of achieving long-term local control with conventional fractio nation. Further improvements to the methodology to address the shortco mings of analyzing diploid tumors may increase the predictive power of the measurement. (C) 1997 Elsevier Science Inc.