BACKGROUNDCells derived from lung cancer are biological heterogeneous and have different intrinsic radiosensitivity, it is a key question for us to investigate radiosensitive parameters for an individualized radiotherapy plan. The comet assay is a sensitive and facilitated method to detect single-cell DNA damage and repair, and the results from it have been proven to be so highly coincident with those from clonogenic assay by cell-line investigations that it has been considered as a promising method in predicting radiosensitivity. The study is designed to evaluate preliminarily the correlation between initial DNA damage detected by alkaline comet assay and the clinical endpoints.

METHODSBiopsy samples from 31 lung cancer patients by fibrous bronchial endoscopy were detected by alkaline comet assay from April, 2002 to November, 2002. The adjusted tail moment (R TM) was measured and thoracic local-region lesions were measured by computer tomography scan. Response rate (RR) and time to progression (TTP) for the local-region lesions were as clinical endpoints. SPSS 10.0 software was used to compare median R TM of different RR and TTP groups by Mann-Whitney U and Kruskal-Wallis H rank test, the correlations between R TM with RR and TTP were estimated by Spearman's rank test.

RESULTSThere were no statistic differences of median R TM among different pathological types with a median R TM of 0.98, 1.27 and 1.05 in squamous cell carcinoma group, adenocarcinoma group and small cell lung cancer group, respectively (Chi-square=0.347, P=0.84). Through a median follow-up of 10 months, a median R TM of 1.08 and 1.21 for squamous cell carcinoma group and small cell lung cancer group in RR≥50% group was greater than 0.88 and 0.91 in RR < 50% group; median R TM in TTP > 9-monthgroups stratified according to pathological type was greater than that in TTP≤9-month groups (1.26, 1.38 and 1.39 versus 0.71, 0.48 and 1.03 for squamous cell carcinoma group, adenocarcinoma group and small cell lung cancer group respectively), but the differences of R TM classified by RR or TTP were not statistically significant (U=63.5, P=0.58; U=71, P=0.057); the Spearman's coefficients of R TM with RR and TTP were -0.105 (P=0.57) and 0.38 (P=0.035). The coefficients of R TM with TTP was 0.47 for non-small cell lung cancer indicating a modest correlation (P=0.048) and 0.043 for small cell lung cancer (P=0.89).

CONCLUSIONSAlthough the results are confounded due to sampling and the greater background tail moments, Spearman's coefficient of R TM with TTP for non-small cell lung cancer indicates a modest positive correlation. The comet assay might be a promising method in predicting intrinsic radiosensitivity of lung cancer cells and techniques for sampling and assaying need to be further improved.

Objective To retrospectively analyze treatment results of radiotherapy for medically inoperable stage Ⅰ/Ⅱ non-small cell lung cancer. Methods Between Jan.2000 and Dec.2005,fifty-eight such patients were enrolled into the database analysis,including 37 with clinical stage Ⅰ and 21 with stage Ⅱ disease.Fifty patients received radiotherapy alone and eight with radiotherapy and chemotherapy.Fortythree patients were treated with 3-D conformal radiotherapy(3D-CRT)and 15 with conventional radiotherapy.Results The 1-,2-and 3- year overall survival rates were 85%,54%and 30%,and the median survival time was 26.2 months for the whole group.The corresponding figures were 88%,60%,36%and 30.8 months for cancer-specific survival:84%,64%,31%and 30.8 months for Stage Ⅰ disease;81%,47%,28%and 18.8 months for Stage Ⅱ disease;95%,57%,33%and 30.8 months for 3D-CRT group and 53%,44%,24%and 15.3 months for conventional radiotherapy group.By logrank test,tumor volume,pneumonitis of Grade Ⅱ or higher and weight loSS more than 5%showed statistically significant impact on overall survival.Tumor volume was the only independent prognostic factor in Cox muhivariable regression.Pneumonitis and esophagitis of Grade Ⅱ or higher were 16%and 2%,respectively.Age and lung function before treatment had a significant relationship with pneumonitis.Failure included the local recurrence(33%)and distant metastasis(21%).There was no difference between the treatment modalities and failure sites. Conclusions For medically inoperable early stage non-small cell lung cancer patients,tumor volume is the most important prognostic factor for overall survival.The conformal radiotherapy marginally improves the survival.The age and pulmonary function are related to the incidence of treatment induced pneumonitis.

Objective To evaluate the efficacy of three-dimensional conformal radiation therapy (3DCRT) for esophageal carcinoma and identify prognostic factors in this patient group.Methods From May 2002 to Jun 2005,132 patients with unresectable or inoperable esophageal cancer were treated with 3DCRT in our hospital.Their chnical data were analyzed retrospectively.ResultsThe 1-and 2-year local control rates was 65.4% and 52.1% in the whole group,respectively.The overall 1-and 2-year survival rate was 50.7% and 32.2% ,respectively.The median survival time was 13 months.The 1-and 2-year survival rate was 56.7%and 36.7% in stageⅠ + Ⅲ ,respectively,with 35.2% and 14.7% in stage IV.The median survival time were 15 months and 9 months for stage Ⅰ +Ⅲ and Ⅳ,respectively(x2 = 8.17,P = 0.004). Of patients with stage Ⅰ + Ⅲ disease who were absent of perforation sign before radiotherapy,with lesion length less than 8.0 cm and whole course given by 3DCRT,the 1-and 2-year survival rate was 73.0% and 49.9%,respectively.Univariate analysis revealed that condition of alimentation,absence of perforation sign, short lesion length,early TNM stage were associated with good survival.Multivariate analysis confirmed that absence of perforation sign and lesion length were independent prognostic factors for survival. Conclusions 3DCRT is effective for esophageal carcinomas in terms of survival and local control.Further improvement could be achieved with muhi-modality treatment.Absence of perforation sign and lesion length are independ ent prognostic factors for survival.

Objective To evaluate the dose distribution and clinical efficacy of hippocampal-sparing prophylactic cranial irradiation ( HS-PCI ) in patients with small cell lung cancer by using helical tomotherapy. Methods Clinical data of 49 patients with small cell lung cancer receiving HS-PCI using helical tomotherapy in Cancer Hospital between 2014 and 2017 were retrospectively analyzed. All patients received brain MRI to exclude the possibility of brain metastasis within 1 month after standard surgery or radio-and chemo-therapy. The prescription dose was 95% PTV,25 Gy in 10 fractions. The adverse reactions and cognitive functions of patients were observed before,6 months and 1 year after treatment,and the dose distribution in the hippocampal gyrus,survival rate and brain metastasis rate were analyzed. Results The median follow-up time was 16 months. The average dose in the hippocampal gyrus was 7. 23 Gy and 8. 46 Gy in the reduction region,which was reduced by 71. 88% and 66. 16% compared with the prescription dose. The maximum dose in the hippocampal gyrus was 10. 66 Gy and 15. 43 Gy in the reduction region. Among 49 patients,8 died,the 1-year survival rate was 85. 1% and the 2-year survival rate was 70. 3%.Nine patients (18. 3%) had brain metastases,and one of them with extensive multiple brain metastases (n＝13) presented with metastasis adjacent to the hippocampal gyrus. The main adverse reactions included mild headache, dizziness and brain edema,whereas no ≥ grade 2 adverse reactions occurred. At 6 months after treatment, the HVLT-R score was significantly decreased,and declined by 6. 78% at 12 months after treatment. The HVLT-R scores did not significantly differ in patients without brain metastasis before and 12 months after treatment ( P＞0. 05 ). Conclusion Application of HS-PCI using helical tomotherapy meets the dose requirement,effectively protects the cognitive function and yields slight adverse reactions.