The treatment of malignant tumor with combination of radiation and drug therapy is becoming increasingly popular. In the combination of both these techniques, it is important to decide whether the purpose of their combined use is: to control subclinical distant metastasis, to improve the frequency of tumor control, or to reduce the degree of side-effects on normal tissues. The basic principle of radiotherapy is to obtain maximum control of tumors with a minimum of complications (therapeutic gain factor (TGF) greater than 1.0). However, in most situations where combined treatment is called for, it appears that the chemical agents used only add their effect to both normal and malignant tissues without any obvious therapeutic benefit. In order to determine the optimal strategy for combined treatment using radiation and drugs, it is essential to perform a well-organized randomized clinical trial.