Background: Colorectal cancer (CRC) is a leading cause of cancer-related death. Oxidative DNA damage may
contribute to cancer risk and the antioxidant paraoxonase is one endogenous free radical scavenger in the human
body which could therefore exert an influeence. Purpose: Aim of this study was to determine the role of serum
arylesterase (ARE) and paraoxonase 1(PON1) activities in CRC patients and to fnd any association between
(PON1) Q192R and L55M gene polymorphisms in CRC patients. Also the serum ARE and PON1 activities in
CRC patients will be investigated before and after surgery Materials and Methods: This study involved a total of
50 patients with newly diagnosed CRC and 80 healthy controls. PON1 and ARE activities were determined using
an enzymatic spectrophotometric method. PON1 Q192R and L55M gene polymorphisms were determined using
polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) based restriction fragment
analysis. The restriction enzyme AlwI was used to examine the Q192R polymorphism and Hsp92II for the L55M
polymorphism. Results: Signifcant differences in the PON1 Q192R polymorphism were found between patients
and controls. The Q allele was more frequent in the patient group than in controls, while the R allele was more
frequent in the controls. Signifcant differences were found in the L55M polymorphism. Additionally, there were
signifcant differences in L and M allele frequencies (p=0.001). The serum activities of PON1 and ARE were
low in QQ and MM genotype. Conclusions:
serum PON1 and ARE activities were signifcantly lower in CRC
patients compared to healthy subjects. The R allele may protect against colorectal cancer.