Potential doubling time in head and neck tumors treated by primary radiotherapy: preliminary evidence for a prognostic significance in local control.

Abstract

The aim of the study was to determine preliminarily whether cell kinetic parameters evaluated using in vivo infusion of bromodeoxyuridine (BrdUrd) and flow cytometry, play a role as prognostic factors of loco-regional control in squamous cell head and neck carcinoma treated with radiotherapy. Between April 1989 and December 1991, 42 patients with unresectable Stage II-IV squamous cell carcinoma of the oral cavity, pharynx or larynx were given an infusion of BrdUrd solution prior to primary tumor biopsy sampling at 4-6 hr later. The simultaneous labeling S-phase fraction (LI) and duration (Ts) as well as the estimated potential doubling time (Tpot) were measured using flow cytometric analysis of BrdUrd and DNA content. Twenty-six patients received standard radiotherapy (70 Gy/35 fractions/7 weeks) whereas 15 patients were treated with the concomitant boost technique (75 Gy/40 fractions/6 weeks). A complete set of flow cytometric data was available for 31 patients. The median value of LI, Ts, and Tpot were 9%, 9 hr and 5 days, respectively. Univariate analysis among the patients treated homogeneously by standard radiotherapy, indicated that local control was affected by Tpot value (p = 0.02). When the same analysis was performed for the patients treated with either standard radiotherapy or concomitant boost regimen, we found a p = 0.04. Thus, patients with a tumor Tpot value < or = 5 days had a significantly lower three-year local control than patients with Tpot > 5 days. Log-rank test univariate analysis showed, in addition, that nodal status was the strongest prognostic factor of local control (p = 0.005). Age, tumor stage, tumor site, performance status, grading, radiotherapy regimen, DNA ploidy and LI value were, instead, not significantly related to loco-regional control. Finally, when comparing the type of radiotherapy for tumors with Tpot < or = 5 days, we found a trend toward a better local control after concomitant boost regimen, with respect to standard regimen (p = 0.06). The present preliminary results suggest that Tpot could play a role as additional prognostic factor influencing the disease outcome in head and neck carcinoma treated by radiotherapy.