Yamauchi K, Kokuryo T, Yokoyama Y, Uehara K, Yamaguchi J, Nagino M

BACKGROUND S-1, an oral 5-fluorouracil (5-FU)-based medicine that combines tegafur, gimeracil and oteracil potassium is commonly used as an adjuvant chemotherapeutic drug for the treatment of colorectal cancer.

PATIENTS AND METHODS We enrolled 53 patients who underwent curative resection for colorectal cancer and liver metastasis (synchronous, n=24; metachronous, n=29). The subsequent adjuvant chemotherapy with oral S-1 administration was initiated within 56 days after liver resection. Recurrence was evaluated by imaging studies, that were performed during the first year after liver resection. Of the 53 patients, 25 who did not recur within 1 year were defined as being in the no-recurrence (NREC) group and the remaining 18 patients were defined as being in the early-recurrence (EREC) group. There were no significant differences in gene expression profiling for drug resistance and metabolism between the NREC group and the EREC group.

RESULTS In synchronous liver metastasis, there was no significant difference in early recurrence between serum carcinoembryonic antigen (CEA) ≤5 ng/ml and serum CEA>5 ng/ml (8/24 vs. 16/24, respectively). In metachronous liver metastasis, the early recurrence rate was significantly higher in patients with CEA>5 ng/ml compared to patients with CEA ≤5 ng/ml (15/29 vs. 14/29, p=0.05). The expression of cytochrome P450 2C19 (CYP2C19) and ATP-binding cassette, sub-family B member 1 (ABCB1) were significantly lower in the EREC group (6/15) compared to the NREC group (9/15) in colorectal cancer with metachronous liver metastasis and with serum CEA>5 ng/ml.

CONCLUSION Although the exact reason for down-regulation of these genes in the group with poor prognosis is unknown, the information obtained in this study may be useful in clinical practice for colorectal cancer.

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