Analysis of the effects of oxygen supply and demand on hypoxic fraction in tumors

The extent of hypoxic regions in a tumor tissue depends on the arrangement, blood flow rate and blood oxygen content of microvessels, and on the tissue's oxygen consumption rate. Here, the effects of blood flow rate, blood oxygen content and oxygen consumption on hypoxic fraction are simulated theoretically, for a region whose microvascular geometry was derived from observations of a transplanted mammary andenocarcinoma (R3230AC) in a rat dorsal skin flap preparation. In the control state, arterial PO₂ is 100 mmHg, consumption rate is 2.4 cm³ O₂/100 g/min, and hypoxic fraction (tissue with PO₂ < 3 mmHg) is 30% Hypoxia is abolished by a reduction in consumption rate of at least 30% relative to control, or an increase in flow rate by a factor of 4 or more, or an increase in arterial PO₂ by a factor of 11 or more. These results suggest that reducing oxygen consumption rate may be more effective than elevating blood flow or oxygen content as a method to reduce tumor hypoxia.