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Objective: one of the present chemotherapy treatment for the end-stage colon cancer is oxaliplatin, but patients who have accepted the same medicine and the dosage treatment, always show great difference among chemotherapy sensitive, the DNA repair gene can play an important role in the drug resistance to oxaliplatin chemotherapy to the patients ,who receive oxaliplatin as chemotherapy treatment.The DNA repair system can be divided into four paths,such as: Nucleot,ide excision repair, basic group excision repair, double strand break repair and enzyme repair.Among of it, the nucleotide excision repair system is the the main mechanism of eliminating massive platinum which causeed the DNA spiral structure distortion. The ability to repair DNA mispairing gene can be affected by the different gene structure and the function.The DNA repair gene’s single nucleotide polymorphism (SNPs) may cause its different repair ability, it can be used to forecast the tumor patient’s sensitivity to the platinum chemotherapy. Human xeroderma pigmentosum G (XPG) is the key important component of nucleotide excision repair gene system, It is responsible to excise the mispairing DNA 3’. We are intend to research the relationship between the single nucleotide polymorphism of gene XPG C46T and the sensitive to platinum class medicine chemotherapy in the end-stage colorectal cancer patients.Methods: Collected 71 patients who are treated at our hospital from September 2009.3 to 2010.12 were enrolled.Patients were required to have pathologically confirmed IV end-stage colorectal cancer.ALL the patients in the group were take FOLFOX chemotherapy treatment which has oxaliplatin as foundation, it is: Before the chemotherapy, extracts peripheral blood 2ml, after citric acid sodium antifreeze, withdraws plasma DNA samples and purifies it, and then design the goal gene fragment’s upstream and downstream directly,by polymerase chain-restrictive fragment length polymorphism (PCR-RFLP) the method examines XPG the C46T the polymorphism of gene , then analyzes the relationship between the chemotherapy sensitivity and different genetype. Finally: among 71 end-rage colorectal cancer patients, we discovered that XPG C/C is 43 example, XPG C/T and T/T respectively is 23 example and 5 example. After patients finished 3-6 cycle chemotherapies, the total number of patients who show sensitivity to oxaliplatin is 43 example, the total effectiveness is 60.56%, XPG C/C is 31 example, XPG C/T and T/T each are 10 example and 2 example, effectiveness respectively are72.09%、43.48%、40%,after analysis statistics,p<0.05.the difference of effectiveness among three groups are very significance .The patients who gene type is wide XPG C/C is better than mutator gene XPG C/T和T/T.Results: 1.The DNA repair gene’s single nucleotide polymorphism XPG C46T can affects patient’s chemotherapy sensitivity, regarding the end-stage colorectal cancer patients,the gene XPG C46T single nucleotide polymorphism have relationship with the sensitive to oxaliplatin treatments,The XPG wild genotype’s chemotherapy effect is better than the mutation gene type.2.Among 71 patients who receive oxaliplatin as the chemotherapy treatments ,the main side effects are II°Myelosuppression、nausea and vomit ,there is no different among three gene type.The examination of XPG gene polymorphisms can be an effect biological marker to forecast that the patients to the chemotherapy sensitivity,can be the effective instruction to clinical medication, realize the tumor patient’s individuation treatments, thus causes the medicine curative effect maximization and reduce the side effects of the drug.
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