Chronology of combined chemotherapy (5FU) and radiotherapy. II. In vivo study

In a previous study, we reported that repeated combined chemotherapy and radiotherapy, and a single combined treatment had different consequences. In this study the effect of the chronology of the repeated combined treatments was tested, i.e. it was determined whether the treatment is more efficient when the first treatment is Fluorouracil or irradiation, or when they are given simultaneously. It was first demonstrated that, under our conditions, neither radiotherapy nor chemotherapy were chronodependent. The combined treatments were more efficient that the single treatment although their chronology had no significant consequences. Nevertheless, the simultaneous treatment appeared slightly better than the administration of Fluorouracil 6 h before or 6 h after irradiation. These results confirm our in vitro experiments.