There is relationship between the polymorphisms of phase Ⅰ, Ⅱ metabolizing enzymes genes as well as DNA repair genes and lung cancer susceptibility. More researches of the relation-ship between lung cancer and some suscepti-ble genes,such as CYP1A1 ,CYP2D6,GSTM1 ,GSTT1 ,XRCC1 ,hOGG1 ,XPD,XPA,XRCC3 are reported.

Objective To analyze the genetic polymorphism of GSTM1 to lung cancer patients in north Sichuan of China and compare with race from other district.Methods PCR-based technique was used to detect the genotypes of GSTM1 in lung cancer patients.Results In local lung cancer patients,the frequency of homozygous deletions(null genotype) for GSTM1 was 58.4 % (73/125).Among the patients,the frequencys of null genotype for GSTM1 were 62.5 % (20/32) in female,56.9 % (53/93) in male,56.1% (32/57)in patients with squamous cell carcinoma and 54.8 % (17/31) in patients with adenocarcinoma,respectively.The frequency of deletions of GSTM1 in lung cancer patients from north Sichuan of China is slightly exceeding those of Europe and Americas (P ＜0.05) and similar to the domestic result (P ＞0.05).Conclusion The genetic polymorphism of GSTM1 to lung cancer patients in north Sichuan of China dosen' t show distinguished feature for this district and race.

Objective:To analyze the dosimetric differences between 3D printed oral stents and corked oral stents in the target area and perioral organ at risk (OAR) in radiotherapy for head and neck cancer, and the effectiveness in reducing acute adverse reactions associated with radiotherapy.Methods:A total of 58 patients with head and neck cancer admitted to Department of Oncology of Affiliated Hospital of North Sichuan Medical College were selected and divided into experimental group (Group A, n=28, wearing 3D printed oral stents during radiotherapy) and control group (Group B, n=30, wearing corked oral stents during radiotherapy) in this retrospective cohort study. The incidence of radiotherapy - induced oral mucositis (RTOM), xerostomia and oropharyngeal mucosal pain was compared between two groups. Meanwhile, informed consent was obtained from 21 patients in Group A. Using the self control method, each patient wore a 3D printed oral stent (Group C) and a corked oral stent (Group D) to make two radiotherapy plans. The differences in the conformity index (CI), homogeneity index (HI) and exposure dose of OAR (D max, D mean) in the target area were analyzed between two groups. SPSS 25.0 statistical software was used for statistical analysis. Measurement data were expressed as Mean±SD. Comparison between two groups was conducted by paired t-test or repeated measurement analysis. Count data were expressed as ratio. Comparison between two groups was performed by Chi - square test or Fisher's exact test. P<0.05 was considered as statistically significant difference. Results:The severity of RTOM ( P<0.05), oropharyngeal mucosal pain ( P=0.004) and xerostomia score ( P<0.001) in Group A were significantly lower than those in Group B. There was no significant difference in the HI and CI of the target area between Group C and Group D (both P>0.05). The D max ( P=0.014, 0.009) and D mean ( P<0.001, P=0.033) of the upper lip and the affected buccal mucosa in Group C were significantly lower than those in Group D. Conclusion:3D printed oral stents obtain favorable HI and CI in radiotherapy for head and neck cancer, significantly reduce the irradiated dose to perioral OAR, and effectively lower the incidence and mitigate the severity of acute RTOM, xerostomia and oropharyngeal mucosal pain associated with radiotherapy.