Changes over time in thymidine phosphorylase and dihydropyrimidine dehydrogenase when colon cancer samples are left at room temperature

The changes over time in thymidine phosphorylase (TP) and dihydropyrimidine dehydrogenase (DPD) were studied when colon cancer samples were left at room temperature. The TP levels and the TP/DPD ratio showed no changes over time in either the tumor or normal tissues. DPD levels increased over time in the normal tissues (P=0.015), but showed no changes in the tumor tissues. When the DPD level in normal tissues is to be examined, the samples should be frozen as soon as possible. In all other cases, the ELISA results will not be affected if the samples are frozen within 6 h after collection.