| Summary: | <p>Abstract</p> <p>Background</p> <p>Early relapse in colorectal cancer (CRC) patients is attributed mainly to the higher malignant entity (such as an unfavorable genotype, deeper tumor invasion, lymph node metastasis and advance cancer stage) and poor response to chemotherapy. Several investigations have demonstrated that genetic polymorphisms in drug-targeted genes, metabolizing enzymes, and DNA-repairing enzymes are all strongly correlated with inter-individual differences in the efficacy and toxicity of many treatment regimens. This preliminary study attempts to identify the correlation between genetic polymorphisms and clinicopathological features of CRC, and evaluates the relationship between genetic polymorphisms and chemotherapeutic susceptibility of Taiwanese CRC patients. To our knowledge, this study discusses, for the first time, early cancer relapse and its indication by multiple genes.</p> <p>Methods</p> <p>Six gene polymorphisms functional in drug-metabolism – <it>GSTP1 </it>Ile105Val, <it>ABCB1 </it>Ile1145Ile, <it>MTHFR </it>Ala222Val, <it>TYMS </it>double (2R) or triple (3R) tandem repeat – and DNA-repair genes – <it>ERCC2 </it>Lys751Gln and <it>XRCC1 A</it>rg399Gln – were assessed in 201 CRC patients using a polymerase chain reaction-restriction fragment-length polymorphism (PCR-RFLP) technique and DNA sequencing. Patients were diagnosed as either high-risk stage II (T2 and 3 N0 M0) or III (any T N1 and 2 M0) and were administered adjuvant chemotherapy regimens that included 5-fluorouracil (5FU) and leucovorin (LV). The correlations between genetic polymorphisms and patient clinicopathological features and relapses were investigated.</p> <p>Results</p> <p>In this study, the distributions of <it>GSTP1 </it>(<it>P </it>= 0.003), <it>ABCB1 </it>(<it>P </it>= 0.001), <it>TYMS </it>(<it>P </it>< 0.0001), <it>ERCC2 </it>(<it>P </it>< 0.0001) and <it>XRCC1 </it>(<it>P </it>= 0.006) genotypes in the Asian population, with the exception of <it>MTHFR </it>(<it>P </it>= 0.081), differed significantly from their distributions in a Caucasian population. However, the unfavorable genotype <it>ERCC2 </it>2251A>C (<it>P </it>= 0.006), tumor invasion depth (<it>P </it>= 0.025), lymph node metastasis (<it>P </it>= 0.011) and cancer stage (<it>P </it>= 0.008) were significantly correlated with early relapse. Patients carrying the <it>ERCC2 </it>2251AC or2251CC genotypes had a significantly increased risk of early relapse (OR = 3.294, 95% CI, 1.272–8.532).</p> <p>Conclusion</p> <p>We suggest that <it>ERCC2 </it>2251A>C alleles may be genetic predictors of early CRC relapse.</p>
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