A model for cancer treatment in advanced compared to early cancer.

Loss of sensitivity to drugs following tumor progression constitutes the main reason for failure of treatment in advanced cancer. In view of the dynamic nature of neoplasms, models of tumor progression should be used for the testing of drugs. In the present study, two variants of malignancy of AKR lymphoma were used as a model of tumor progression to test various treatment modalities. The two variants, TAU-39 (of low-malignancy) and TAU-38 (of high-malignancy) differed in the pattern of local tumor growth as well as in the rate of metastatic spread and mice killing capacity. The efficiency of chemotherapy, immunotherapy and hyperthermia on the two variants was compared. The low-malignancy tumor was more sensitive to adriamycin than the high-malignancy one. Administration of levan-activated macrophages at the tumor site inhibited the growth of TAU-39. However, growth of the high-malignancy variant was stimulated by macrophages. Hyperthermic treatment was, in contrast to the other treatments, more effective against the high - than against the low-malignancy tumor. Models of tumor progression used in tests for antitumoral drugs may help in the discovery of treatment modalities effective also for advanced stages of cancer.