Effect of microspheres in intra-arterial chemotherapy. A study of arterio-venous shunting and passage of a labelled marker.

Degradable starch microspheres (DSM) mixed and injected with a cytostatic drug might improve intra-arterial chemotherapy by increasing the local drug concentration. Several factors are of importance for an optimal effect of the microspheres, e.g. size and vascularity of the tumour, arterial blood flow and arterio-venous shunts. Therefore, the dose of DSM has to be individualized. A method for continuous monitoring of the effect of DSM was developed. A radiolabelled marker was injected intra-arterially mixed with DSM and mitomycin C. Two kinetic parameters--Passing Fraction and Marker Flow Rate--were found to be influenced by the microspheres and thus seemed to be useful for monitoring the DSM-treatment. Arterio-venous shunting was measured as passage of 99Tcm-labelled macroaggregated albumin through the liver to the lungs. Significant increase of shunting after injection of DSM was demonstrated in 15 out of 19 patients. Almost no effect of the microspheres was seen in patients with marked arterio-venous shunting or minimal reduction of the marker flow rate, but in others the passage of the labelled marker could generally be significantly reduced.