Chronology of combined chemotherapy (5FU) and radiotherapy. I. In vitro study.

Since radiotherapy or chemotherapy alone may be ineffective, they are more and more often combined. In this in vitro studies the effects of the chronology of the treatments and of the time interval between them are evaluated. In murine leukaemia L1210 cells and in murine mammary adenocarcinoma Ca755 cells the highest efficacy, i.e. the lowest survival fraction, was observed when radiotherapy was administered 6 h before Fluorouracil (FU). To mimic treatment in man, a daily combined treatment was also tested. Under these circumstances, the chronology of the treatments and the time interval between them had different consequences, the highest efficacy being noticed when both treatments were given at the same time.