Early Changes in 2-Deoxy-2-[18F]Fluoro-D-Glucose Metabolism in Squamous-Cell Carcinoma During Chemotherapy in Vivo and In Vitro

Aim: The aim of this study was to investigate early changes in uptake of 2-deoxy-2-[F-18]fluoro-D-glucose (FDG) in vivo and in vitro in a squamous-cell carcinoma (SCC) cell line originating from a human head and neck SCC during cytotoxic therapy with respect to metabolism in tumor cells and in surrounding stromal tissue. Materials and Methods: In 60 nude mice with xenografted SCC, 50 animals were treated with cisplatin. Early changes in the tumor FDG uptake following therapy were evaluated sequentially with phosphor imaging. Using this technique, areas with focal hypermetabolism were detected. The cells creating the focal hypermetabolism were then identified histopathologically on the corresponding sections. In addition, early FDG uptake versus the number of viable tumor cells was measured in vitro following cisplatin treatment. Results: An early transient increase in FDG uptake in tumor cells was seen on day 1 in treated tumors, followed by a rapid decrease confirmed by subsequent tumor regression. This metabolic flare was present in all treated tumors but not in the controls. In vitro, an increase in FDG uptake per cell was observed. Conclusions: Our results provide new insights into the early metabolic changes in squamous-cell carcinomas subjected to cytotoxic therapy and thus contribute to the discussion on the feasibility of early predictive PET studies.