Potentiation of the antitumor action of 5-fluorouracil with 5-ethyl-2'-deoxyuridine in human colorectal tumor xenografts.

The tumor growth inhibitory effect of 5-ethyl-2'-deoxyuridine ( EUdR ) in combination with 5-fluorouracil (5-FU) has been studied on four human colorectal xenograft lines. In all lines the EUdR pretreatment potentiated the effect of 5-FU presumably due to the increased incorporation of 5-FU into RNA via elevated intracellular thymidine concentration and decreased rate of 5-FU catabolism.