[Biological evaluation of chemo-radiotherapy combined with cisplatin]

Biological basis for the combined chemo-radiotherapy which may be required for the useful application to the radiotherapy combined with cisplatin was discussed. Experimental data have suggested that cisplatin is useful for increasing the therapeutic gain if the tumor is sensitive for cisplatin alone. However, it was revealed from our experiment that a mouse carcinoma as in human tumors contains several clones which differ in their sensitivities to both radiation and cisplatin, and further that the radioresistant clone also showed the resistance to cisplatin. It was considered from both experimental and clinical outcome that the development of more efficient assay method for drug-sensitivity as well as that of therapeutic regimens for preventing cellular proliferation of drug- or radiation-resistant subclones was important.