QUANTITATIVE DNA ANALYSIS OF AN INTRACEREBRALLY TRANSPLANTED BRAIN-TUMOR MODEL AFTER EXPERIMENTAL CHEMOTHERAPY WITH BCNU AND CCNU

In the present study we investigated the susceptibility of high passag es of the rat glial transplantation tumour G-XIII to chemotherapy usin g nitrosourea compounds. We observed a significant increase in lifespa n (ILS) of animals treated with BCNU (37 %, p < 0.01) and CCNU (27 %, p < 0.01). There were no difference in the efficiency between these tw o substances. Using a semi-quantitative score system no histopathologi cal changes were observed which were associated with the response to t herapy. The only predicative parameter in the present study was the qu antitative DNA distribution pattern. There was a close correlation bet ween treatment and the occurrence of unimodal DNA distribution pattern s indicating clonal regrowth of recurrent tumours. Moreover, we also o bserved a correlation of the DNA distribution pattern of recurrent tum ours with the result of experimental chemotherapy. Survival times of a nimals suffering from tumours containing unimodal DNA histogram was si gnificantly longer than survival times of rats with multimodal DNA dis tribution, i.e. bimodal or broad DNA histograms. A unimodal, near-dipl oid stem line was only present in treated animals suggesting that thes e clones are more resistant against therapy using nitrosourea compound s. Our data indicate DNA cytophotometry as comprehensive tool for the monitoring of therapy response and the design of experimental chemothe rapy using rat glial tumours.