Association of time to recurrence with thymidylate synthase and dihydropyrimidine dehydrogenase mRNA expression in stage II and III colorectal cancer

III rectal cancer may receive adjuvant chemotherapy with 5-fluorouracil (5-FU). High levels of thymidylate synthase (TS) and dihydropyrimidine dehydrogenase (DPD) have been associated with resistance to 5-FU in advanced colorectal cancer. The aim of this study was to investigate the association of TS and DPD mRNA levels with recurrence-free survival in patients with colorectal cancer who are receiving adjuvant 5-FU-based chemotherapy. TS and DPD mRNA quantitation was retrospectively performed in primary colorectal cancer specimens from patients receiving adjuvant 5-FU using a reverse transcription-polymerase chain reaction technique. The median TS mRNA level in patients with a recurrence (n = 142) was 0.68, and in patients without a recurrence (n = 206) the median level was 0.80 (P < 0.01). Patients with a recurrence who had a low TS level (TS ≤ 0.9; n = t02) had a median recurrence-free survival of 18 months (range 3.0 to 54 months), and those with a high TS level (TS > 0.9; n = 40) had a median recurrence-free survival of 11 months (range 1.7 to 53 months; P = 0.0024). There was no difference in the median recurrence-free survival of patients with low and high DPD mRNA levels. The TS mRNA level may be a useful marker to predict the time to recurrence in patients with colorectal cancer who are receiving adjuvant 5-FU treatment.