Purpose: The present study analyzed the polymorphisms of DNA repair genes and their impact on the response to chemotherapy and survival of patients with colorectal cancer.
Patients and methods: A total of 94 patients with recurrent or metastatic colorectal cancer treated with oxaliplatin-based combination chemotherapy were enrolled in the present study. The single nucleotide polymorphisms of 16 DNA repair genes were determined using a PCR-RFLP assay.
Results: During the median follow-up duration of 15.9 (2.1-53.0) months, 67 (71.3%) progressions and 29 (30.9%) deaths were observed. Among the 60 patients assessable for response, response to the oxaliplatin-based regimens was found in 27 (45%) patients (9 CR and 18 PR). In a logistic regression analysis adjusted to age, sex, primary site, disease status, and regimen, the POLR2C rs4937 and MSH2 rs3732183 polymorphisms were statistically associated with the response to the oxaliplatin-based chemotherapy. A multivariate survival analysis showed that the TT genotype of the MGMT (rs1625649) -535G>T polymorphism was found to correlate with a worse progression-free survival (PFS) than the combined GG + GT genotypes (HR = 3.137; 95% CI = 1.423-6.914; P = 0.005), which was also observed among the 60 evaluable patients (HR = 2.653; 95% CI = 1.101-6.392; P = 0.030) For the clinical parameters, curative resection was the most significant prognostic factor in a Cox model for PFS and overall survival (HR = 0.229 and 0.205; P < 0.001 and 0.001, respectively).
Conclusion: The MGMT -535G>T polymorphism (rs1625649) was found to be correlated with PFS in patients with advanced colorectal cancer treated with oxaliplatin-based chemotherapy.