The Relationship Between Polymorphisms Of XRCC1 Codon399 And The Short-term Effect Of Radiotherapy In Nasopharyngeal Carcinoma

Objective:By detecting the polymorphisms of XRCC1 Codon399 of the patients suffering from nasopharyngeal carcinoma(NPC),observing the different short-term effect of radiotherapy,to find the intrinsic factors which influence radiosensitivity.Methods:Phlebotomize 60 patients of low differentiated NPC and extract genome DNA from whole blood cells.Then perform PCR,and amplify the PCR products by ligase detection reaction,put the LDR products on sequencer to carry out electrophoresis,get the genotype of XRCC1 Codon399.To observe the size of tumor at local nasopharynx and metastasis lymph nodes,then calculate the regression rate when dose reaches 36～40Gy;to observe the effect of radiotherapy of NPC at 3 months after finishing radiation;to observe the acute irradiation induced injury of skin and mucous membrane during radiotherapy.Results:(1)Of all cases,the number of XRCC1 Codon399 Gln/Gln was 6,Arg/Gln was 21, Arg/Arg was 33;there was no significant difference among the three genotypes on age, gender,clinical stage,T stage,N stage(P＞0.05).(2)After mid-course of radiotherapy the regression rate of Gln/Gln genotype at local nasopharynx and metastasis lymph node was 0.855±0.026,0.923±0.092 respectively,higer than Arg/Gln(0.386±0.183,0.589±0.166)and Arg/Arg genotype(0.377±0.169,0.454±0.209), there was significant difference among the three genotypes(F=11.16,P=0.0003 and F=10.97,P=0.0002). (3)The CR rate at 3 months after radiotherapy of the cases with Gln/Gln at local nasopharynx and metastasis lymph node was 100%,100%,Arg/Gln was 76.2%,80.0%, Arg/Arg was 66.7%,65.0%respectively,but there was no significant difference among the three genotypes(P＞0.05);univariate analysis revealed a significant relationship between the T stage,clinical stage and the response rate of local nasopharyngeal carcinoma at 3 months after radiotherapy,but no significant relationship with N stage.(4)All cases had suffered from the acute irradiation induced injury of skin and mucous membrane to some extent.The rate of the acute irradiation induced injury of skin and mucous membrane at Grade 3 and above was 33.3%and 16.7%in cases with Gln/Gln,4.8%and 9.5%with Arg/Gln,6.1%and 9.1%with Arg/Arg.But there was no significant difference among the 3 genotypes.Conclusion:(1)The tumor regression rate of the NPC patients with Gln/Gln is higher than the other two genotypes at mid-course of radiotherapy.(2)The effect of radiotherapy of NPC at local nasopharynx at 3 months after finishing radiation is related to T stage and clinical stage,but no relationship with the polymorphisms of XRCC1 Codon399.(3)There is no relationship between the polymorphisms of XRCC1 Codon399 and the acute irradiation induced injury of skin and mucous membrane during radiotherapy.