Complications of Combined Radiotherapy and Chemotherapy

The radiation-modifying effect of cancer chemotherapeutic drugs is reviewed based on experimental studies covering skin, esophagus, intestinal tract, lungs, kidney, bladder, testis, and hematopoietic tissue. The results obtained in experimental studies have, whenever possible, been compared with observations of normal tissue reactions in clinical practice. Such a comparison of experimental and clinical data is difficult and should be cautiously interpreted. However, where comparable data are available there seems to be a reasonable agreement between experimental and clinical data. It appears that drugs with an effect on the tissue by itself should especially be expected to enhance the radiation response in that specific tissue. Concerning the importance of the intervals and sequence of the two treatment modalities, experimental data seem to indicate the effect of timing in clinical practice. The best way to avoid enhanced reactions in normal tissues is to separate the two treatment modalities in time and, possibly, to administer chemotherapy before radiotherapy. Experimental data should be cautiously considered, together with clinical experience, in planning of drug-radiation combinations to avoid unacceptable reactions in critical normal tissues. Guidelines for the clinical use of combined radiotherapy and chemotherapy are proposed.