Figure 1. Comparison of model predictions with experimental data.

The experimental data have been redrawn from Fig. 3 in ref. 35 and refer to measurements of partial oxygen pressure (pO₂) in the tumour interstitium as a function of the distance from blood vessels (circles; bars represents the s.e.m. calculated from 15 samples). Here pO₂ has been normalised with respect to the central value in the nearest blood vessel (). The lines represent the stationary solutions obtained from a reaction-diffusion model–discussed further on in the main text–with different values of the oxygen diffusion coefficient and with a measured consumption rate. Blue line: measured value of the diffusion coefficient in the tumour interstitium; red line: diffusion coefficient of oxygen in water, almost twice larger than the diffusion coefficient in the interstitium; green line: diffusion coefficient halved with respect to measured value in the interstitium; the oxygen consumption coefficient is taken as the measured value in refs ²⁸, ²⁹, ³⁰. It is clear that the inadequacy of the stationary solutions does not depend on the variability of the diffusion coefficient.