MULTI-REGION MODELS FOR DESCRIBING OXYGEN TENSION PROFILES IN HUMAN TUMORS

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Abstract
Multi-region simultaneous diffusion-reaction models are presented for describing oxygen tension profiles in human tumors. The models characterize the spherical tumor mass as either two regions, a central core of necrosis surrounded by a viable layer, or three regions where the viable layer is divided into a hypoxic region surrounded by a well-oxygenated rim. Estimates for the model parameters are based on steady-state clinical measurements obtained in-vivo in humans via a microelectrode—CT scanning technique developed and performed at the Fox Chase Cancer Center. Models employing linear kinetic rate forms for oxygen consumption via cell respiration accurately reproduce the oxygen tension profiles in the ten different carcinoma and sarcoma investigated. Large tumors (7.0 cm in diameter or larger) which typically outgrow their blood supply have sharp profiles that are accurately represented by a two-region model. Conversely, small tumors (4.8 cm in diameter or less)which have a relatively high degree of vascularity require a three-region model to accurately reproduce their oxygen tension profiles.