Study of the Relationship between ERCC1 Polymorphisms and Response to Platinum-based Chemotherapy in Iranian Patients with Colorectal and Gastric Cancers

This study was designed to evaluate the effect of excision repair crosscomplementing group 1 (ERCC1) rs11615 codon 118C/T gene polymorphisms ontreatment outcomes in Iranian patients receiving oxaliplatin-based regimens forcolorectal (CRC) and gastric cancers (GC). Patients, who were candidates to receiveoxaliplatin-based chemotherapy, entered into the study. In 2-week intervals, thepatients received combination regimen of oxaliplatin, fluorouracil, and leucovorin(FOLFOX) for 3 months. ERCC1 rs11615 codon 118C/T polymorphism was testedby restriction fragment length polymorphism polymerase chain reaction (RFLPPCR)method using patients’ peripheral blood lymphocytes. The tumor response tochemotherapy was evaluated by examining the size of the tumor using CT scan.Association between response rates, according to the RECIST criteria, and patients’genotypes was evaluated. Any relationship between response rate and possibleexplanatory factors was also determined. Overall, 40 patients (13 females (32.5%),and 27 males (67.5%)) enrolled in the study. Four patients (10.0%) carried the homozygousmutation (T/T genotype), ten patients (25.0%) were heterozygous (C/Tgenotype), and twenty-six patients (65%) were homozygous (C/C genotype).Response rate were 30.77%, 20.00%, and 0.00% for the genotypes C/C, C/T, andT/T, respectively. No significant association between response rate and genotypeswas observed (p = 0.64). Patients with well- and moderately-differentiatedhistological grade of the tumor showed a better response rate (100.00% of 2 patientsand 66.66% of 12 patients, respectively) compared to those with poorlydifferentiated (0.00% of 26 patients) histological grade (p < 0.001). Furthermulticenter studies are recommended to confirm conclusively our findings.