Prediction of S-1-induced anemia

S-1, a novel oral fluoropyrimidine, has shown remarkably good tolerability in Korean gastric and colorectal cancer patients due to its favorable safety profile. Myelosuppression and diarrhea were the events that precluded dose escalation in Japan, whereas gastrointestinal toxicity and skin reaction were the major limiting factors in Western countries. In contrast, the major adverse event in Korean patients was anemia, which appeared early in the S-1 treatment period and varied among patients. Conventional comparative genomic hybridization (CGH) is used to screen for chromosomal copy number variations such as gene gain, loss, amplification, and deletion. This technique can provide information about genetic instability and chromosomal rearrangements. However, the low resolution of 5-10 Mb is a caveat with conventional CGH. cDNA microarray-based CGH is a useful technique for achieving higher resolution for the detection of genomic aberrations. Pharmacogenomic markers, in combination with clinical factors such as initial hemoglobin level, may be useful for predicting S-1 treatment-induced anemia. Prospective genomic and clinical validation of this model may provide a predictive model for the clinical application of S-1 treatment.