Measurement of tumor oxygenation: In vivo comparison of a luminescence fiber-optic sensor and a polarographic electrode in the P22 tumor

Hypoxia is important in tumor biology and therapy. This study compared the novel luminescence fiber-optic OxyLite sensor with the Eppendorf polarograp hic electrode in measuring tumor oxygenation. Using the relatively well-oxy genated P22 tumor, oxygen measurements were made with both instruments in t he same individual tumors. In 24 air-breathing animals, pooled electrode pO (2) readings lay in a range over twice that of sensor pO(2(5min)) values (- 3.2 to 80 mmHg and -0.1 to 34.8 mmHg, respectively). However, there was no significant difference between the means +/- 2 SE of the median pO(2) value s recorded by each instrument (11.0 +/- 3.3 and 8.1 +/- 1.9 mmHg, for the e lectrode and sensor respectively, P = 0.07), In a group of 12 animals treat ed with carbon monoxide inhalation to induce tumor hypoxia, there was a sma ll but significant difference between the means +/- 2 SE of the median pO(2 ) values reported by the electrode and sensor (1.7 +/- 0.9 and 2.9 +/- 0.7 mmHg, respectively, P = 0.009), A variable degree of disparity was seen on comparison of pairs of median pO(2) values from individual tumors in both a ir-breathing and carbon monoxide-breathing animals. Despite the differences between the sets of readings made with each instrument from individual tum ors, we have shown that the two instruments provide comparable assessments of tumor oxygenation in groups of tumors, over the range of median pO(2) va lues of 0.6 to 28.1. mmHg. (C) 2001 by Radiation Research Society.