Intracapillary oxyhemoglobin saturation of malignant tumors in humans

The oxygenation of cancer tissue in humans has been assessed by measuring the intracapillary oxyhemoglobin saturations (i.c.HbO 2) in solid tumors of the oral cavity using a cryophotometric micrometbod. From histological investigations the tumors can be classified into three qualities of vascularization: (i) well vascularized tumors, (ii) tumors with medium quality of vascularization, and (iii) poorly vascularized tumors. In all three tumor types i.c.HbO 2 distribution curves are shifted to significantly lower values than saturation curves in normal oral mucosa. The extent of this shift can be related to the degree of the reduction in tumor vasculature. In addition, great regional inhomogeneities in i.c.HbO 2 values can be detected. Comparison of these results with earlier measurements in the DS-Carcinosarcoma of the rat reveals that i.c.HbO 2 values in implantation tumors of rats are considerably lower than saturations in tumors of the oral cavity in humans as involved in this study. The differences in tumor oxygenation can be explained by differences in growth stage, in the site of tumor growth, and in influences of the host on the tumor oxygenation.