[The problems of combining chemotherapy and radiotherapy]

The purpose of combined chemotherapy (CT) and radiotherapy (RT) is to improve the therapeutic ratio. The increase of the Therapeutic Gain Factor in combination of the two modalities may be obtained by the following methods; 1) the use of CT and RT under consideration of the difference of the sensitivities of cell cycle 2) the development of the effective drugs to the resting cells such as PLDR inhibitors 3) optimal time sequence between drug and radiation administration 4) the use of drugs by their selective toxicities toward oxygenated and hypoxic tumor cells. 5) the use of hyperthermia 6) increased drug delivery and uptake.