Abstract
BackgroundEarly 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.MethodsSix gene polymorphisms functional in drug-metabolism – GSTP1 Ile105Val, ABCB1 Ile1145Ile, MTHFR Ala222Val, TYMS double (2R) or triple (3R) tandem repeat – and DNA-repair genes – ERCC2 Lys751Gln and XRCC1 Arg399Gln – 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.ResultsIn this study, the distributions of GSTP1 (P = 0.003), ABCB1 (P = 0.001), TYMS (P < 0.0001), ERCC2 (P < 0.0001) and XRCC1 (P = 0.006) genotypes in the Asian population, with the exception of MTHFR (P = 0.081), differed significantly from their distributions in a Caucasian population. However, the unfavorable genotype ERCC2 2251A>C (P = 0.006), tumor invasion depth (P = 0.025), lymph node metastasis (P = 0.011) and cancer stage (P = 0.008) were significantly correlated with early relapse. Patients carrying the ERCC2 2251AC or2251CC genotypes had a significantly increased risk of early relapse (OR = 3.294, 95% CI, 1.272–8.532).ConclusionWe suggest that ERCC2 2251A>C alleles may be genetic predictors of early CRC relapse.
Highlights
Relapse in colorectal cancer (CRC) patients is attributed mainly to the higher malignant entity and poor response to chemotherapy
This study suggests that CRC patients who have the excision repair cross-complementing rodent repair deficiency (ERCC2) 2251AC (751Lys/Gln) or 2251CC (751Glu/Gln) genotypes have a significantly increased early relapse risk (OR = 3.294; 95% confidence interval (CI), 1.272–8.532), and no statistically significant correlation exists between genotype distributions and clinicopathological features
Experimental results in this study indicate that the ERCC2 2251A>C AC and CC gene polymorphisms can predict early relapse; these experimental results are in agreement with the risk role of the C (Glu) allele of ERCC2 Lys751Gln in early relapse
Summary
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. CRC remains the third major cause of cancer-related death in Taiwan, accounting for >3,000 deaths per year [2]. CRC relapse is strongly correlated with chemotherapeutic drug response [1,5,6]
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