... standard dose group, shown in Figure 2. The disap-pearance of circadian rhythm in the 5-FU plasma concentration of the higher dose can be explained by the inhibition of DPD. In conclusion, ... conclusion, the dose-escalation of 5-FU results in a preferable clinical response, especially in ad-vanced ESCC patients, and this is explained, in part, by a higher plasma concentration of 5-FU. The ... dose. The DPD activity is inhib-ited by 5-FU administration [22], and this might con-tribute to the increase in the concentration of 5-FU in the second cycle compared to the first cycle in the...