ATM polymorphisms are associated with risk of radiation-induced pneumonitis

Association of a genetic variation in a miR-191 binding site in MDM4 with risk of esophageal squamous cell carcinoma

As an oncoprotein, MDM4 plays a key part in P53 tumor suppressor pathway through negatively regulating P53 function. It has been reported that an rs4245739 A>C polymorphism locating in the MDM4 3′-untranslated region creates a miR-191 target site and results in decreased MDM4 expression. Therefore, we investigated the association between this polymorphism and esophageal squamous cell carcinoma (ESCC) risk as well as its biological function in vivo. Genotypes were determined in two independent case-control sets consisted of 1128 ESCC cases and 1150 controls from two regions of China. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated by logistic regression. The impact of the polymorphism on MDM4 expression was examined with esophagus tissues. Our results demonstrated that the MDM4 rs4245739 AC and CC genotypes were significantly associated with decreased ESCC risk compared with the AA genotype in both case-control sets (Jinan set: OR = 0.54, 95% CI = 0.35–0.82, P = 0.004; Huaian set: OR = 0.68, 95% CI = 0.45–0.99, P = 0.049). Stratified analyses revealed that a multiplicative interaction between rs4245739 and smoking or drinking was evident (Gene-smoking: P_interactioin = 0.022; gene-drinking: P_interactioin = 0.032). After detecting In vivo MDM4 mRNA expression, we found that the rs4245739 AC and CC genotype carriers had significantly decreased MDM4 expression in normal esophagus tissues compared with AA genotype carriers, indicating a consistent genotype-phenotype correlation. Our results elucidate that the MDM4 rs4245739 polymorphism contributes to susceptibility of ESCC and support the hypothesis that genetic variants, interrupting miRNA-mediated gene regulation, may modify cancer risk.

Analysis of single nucleotide polymorphisms and radiation sensitivity of the lung assessed with an objective radiologic endpoin

BACKGROUND

The primary objective of this study was to evaluate the association between radiation sensitivity of the lungs and candidate single nucleotide polymorphisms (SNP) in genes implicated in radiation-induced toxicity.

METHODS

Patients with lung cancer who received radiation therapy (RT) had pre-RT and serial post-RT single photon emission computed tomography (SPECT) lung perfusion scans. RT-induced changes in regional perfusion were related to regional dose, which generated patient-specific dose-response curves (DRC). The slope of the DRC is independent of total dose and the irradiated volume, and is taken as a reflection of the patient's inherent sensitivity to RT. DNA was extracted from blood samples obtained at baseline. SNPs were determined by using a combination of high-resolution melting, TaqMan assays, and direct sequencing. Genotypes from 33 SNPs in 22 genes were compared against the slope of the DRC by using the Kruskal-Wallis test for ordered alternatives.

RESULTS

Thirty-nine self-reported Caucasian patients with pre-RT and ≥6 month post-RT SPECTs, and blood samples were identified. An association between genotype and increasing slope of the DRC was noted in G(1301) A in XRCC1 (rs25487) (P = .01) and G(3748) A in BRCA1 (rs16942) (P = .03).

CONCLUSIONS

By using an objective radiologic assessment, polymorphisms within genes involved in repair of DNA damage (XRCC1 and BRCA1) were associated with radiation sensitivity of the lungs.

ATM polymorphisms predict severe radiation pneumonitis in patients with non-small cell lung cancer treated with definitive radiation therapy

PURPOSE

The ataxia telangiectasia mutated (ATM) gene mediates detection and repair of DNA damage. We investigated associations between ATM polymorphisms and severe radiation-induced pneumonitis (RP).

METHODS AND MATERIALS

We genotyped 3 potentially functional single nucleotide polymorphisms (SNPs) of ATM (rs1801516 [D1853N/5557G>A], rs189037 [-111G>A] and rs228590) in 362 patients with non-small cell lung cancer (NSCLC), who received definitive (chemo)radiation therapy. The cumulative severe RP probabilities by genotypes were evaluated using the Kaplan-Meier analysis. The associations between severe RP risk and genotypes were assessed by both logistic regression analysis and Cox proportional hazard model with time to event considered.

RESULTS

Of 362 patients (72.4% of non-Hispanic whites), 56 (15.5%) experienced grade ≥3 RP. Patients carrying ATM rs189037 AG/GG or rs228590 TT/CT genotypes or rs189037G/rs228590T/rs1801516G (G-T-G) haplotype had a lower risk of severe RP (rs189037: GG/AG vs AA, adjusted hazard ratio [HR] = 0.49, 95% confidence interval [CI], 0.29-0.83, P=.009; rs228590: TT/CT vs CC, HR=0.57, 95% CI, 0.33-0.97, P=.036; haplotype: G-T-G vs A-C-G, HR=0.52, 95% CI, 0.35-0.79, P=.002). Such positive findings remained in non-Hispanic whites.

CONCLUSIONS

ATM polymorphisms may serve as biomarkers for susceptibility to severe RP in non-Hispanic whites. Large prospective studies are required to confirm our findings.

Prediction of radiation pneumonitis in lung cancer patients: a systematic review

PURPOSE

Factors prediction in the development of radiation pneumonitis (RP) remains unclear. A meta-analysis about this was performed.

MATERIALS

Articles were searched in February 2012 from PubMed, EMBASE, Cochrane Library and CNKI (Chinese Journal Full-text Database) using the keywords "lung cancer," "radiation pneumonitis" or "radiation lung injury." The outcome was the RP incidence. We pooled the data using RevMan 5.1 software and tested the statistical heterogeneity.

RESULTS

We included the following factors: age, gender, weight loss, smoking history, complications, performance status, pre-radiation therapy (RT) pulmonary function, TNM, histological type, tumor location, pre-RT surgery, RT combined with chemotherapy (RCT), RT/RCT combined with amifostine, plasma end/pre-RT TGF-β1 ratio and irradiation volume. The significant risk factors for RP ≥ grade 2 were patients with chronic lung disease, tumor located in the middle or lower lobe, without pre-RT surgery, RCT, plasma end/pre-RT TGF-β1 ratio ≥1 and gross tumor volume (GTV). Following factors were identified significant for RP, including tumor located not in the upper lobe, smokers, combined with chronic lung diseases or diabetes mellitus, low pre-RT pulmonary function, RCT, RT/RCT without amifostine and plasma end/pre-RT TGF-β1 ratio ≥1. Dose-volume parameters included the average of mean lung dose (MLD) of disease lung, GTV and V (5), V (10) (≥34 %), V (20) (≥25 %), V (30) (≥18 %) of bilateral lung.

CONCLUSIONS

More attention should be paid to the levels of patients' pulmonary function, plasma TGF-β1 and dose-volume histogram (DVH). Rigorous studies are needed to identify the relationship between the above-mentioned factors and RP ≥grade 1 or 3.

Serum superoxide dismutase, a potential predictor for radiation pneumonitis following chemoradiotherapy in non-small cell lung cancer patients

PURPOSE

To explore serum superoxide dismutase (SOD) for predicting radiation pneumonitis (RP) in non-small cell lung cancer patients following chemoradiotherapy.

METHODS

Serum levels for SOD were measured by enzyme-linked immunosorbent assays prior to radiation therapy (Pre-RT) and post 40 Gy/4 weeks during the treatment (Pos-RT).

RESULTS

SOD concentrations after delivery of 40 Gy/4 weeks was associated with the development of RP. The best predictive ability of SOD was observed for a cut-off value of 56 unit/ml, with a sensitivity of 0.80 (95% CI 0.28-0.99), and a specificity of 0.67 (95% CI 0.43-0.65) (p = 0.040).

CONCLUSION

Serum SOD may be a potential predictor for RP, which need to be further verified.

Second malignant neoplasms and cardiovascular disease following radiotherapy

Second malignant neoplasms (SMNs) and cardiovascular disease (CVD) are among the most serious and life-threatening late adverse effects experienced by the growing number of cancer survivors worldwide and are due in part to radiotherapy. The National Council on Radiation Protection and Measurements (NCRP) convened an expert scientific committee to critically and comprehensively review associations between radiotherapy and SMNs and CVD, taking into account radiobiology; genomics; treatment (ie, radiotherapy with or without chemotherapy and other therapies); type of radiation; and quantitative considerations (ie, dose-response relationships). Major conclusions of the NCRP include: 1) the relevance of older technologies for current risk assessment when organ-specific absorbed dose and the appropriate relative biological effectiveness are taken into account and 2) the identification of critical research needs with regard to newer radiation modalities, dose-response relationships, and genetic susceptibility. Recommendation for research priorities and infrastructural requirements include 1) long-term large-scale follow-up of extant cancer survivors and prospectively treated patients to characterize risks of SMNs and CVD in terms of radiation dose and type; 2) biological sample collection to integrate epidemiological studies with molecular and genetic evaluations; 3) investigation of interactions between radiotherapy and other potential confounding factors, such as age, sex, race, tobacco and alcohol use, dietary intake, energy balance, and other cofactors, as well as genetic susceptibility; 4) focusing on adolescent and young adult cancer survivors, given the sparse research in this population; and 5) construction of comprehensive risk prediction models for SMNs and CVD to permit the development of follow-up guidelines and prevention and intervention strategies.

A single-nucleotide polymorphism in the methylene tetrahydrofolate reductase (MTHFR) gene is associated with risk of radiation pneumonitis in lung cancer patients treated with thoracic radiation therapy

BACKGROUND

This study examined the association between functional single-nucleotide polymorphisms in candidate genes from oxidative stress pathways and risk of radiation pneumonitis (RP) in patients treated with thoracic radiation therapy for locally advanced lung cancer.

METHODS

A review was conducted of 136 patients treated with radiation therapy for lung cancer between 2001 and 2007, and who had prior genotyping of functional single-nucleotide polymorphisms in oxidative stress genes including superoxide dismutase 2 (SOD2; rs4880) and methylene tetrahydrofolate reductase (MTHFR; rs1801131, rs1801133). RP events were retrospectively scored using the National Cancer Institute Common Terminology Criteria for Adverse Events, version 4.0. Cox proportional hazard regression was performed to identify clinical variables and genotypes associated with risk of RP of grades ≥2 and ≥3 on univariate and multivariate analysis, respectively. P values were corrected for multiple hypothesis esting.

RESULTS

With a median follow-up of 21.4 months, the incidence of grade ≥2 RP was 29% and grade ≥3 RP was 14%. On multivariate analysis, after adjusting for clinical factors such as concurrent chemotherapy and consolidation docetaxel, and lung dosimetric parameters such as volume receiving greater than 20 Gy and mean lung dose, MTHFR genotype (rs1801131; AA versus AC/CC) was significantly associated with risk of grade ≥2 RP (hazard ratio: 0.37; 95% confidence interval: 0.18-0.76; P = .006, corrected P = .018) and grade ≥3 RP (hazard ratio: 0.21; 95% confidence interval: 0.06-0.70; P = .01; corrected P = .03). SOD2 genotype was not associated with RP.

CONCLUSIONS

This study showed an association between MTHFR genotype and risk of clinically significant RP. Further study of MTHFR-related pathways may provide insight into the mechanisms behind RP.

Identification of SNPs associated with susceptibility for development of adverse reactions to radiotherapy

Although cancer treatment with radiation can produce high cure rates, adverse effects often result from radiotherapy. These toxicities are manifested as damage to normal tissues and organs in the radiation field. In recognition of the substantial variation in the intrinsic response of individuals to radiation, an effort began approximately 10 years ago to discover the genetic markers, primarily SNPs, which are associated with susceptibility for the development of these adverse responses to radiation therapy. The goal of this research is to identify the SNPs that could serve as the basis of an assay to predict which cancer patients are most likely to develop complications resulting from radiotherapy. This would permit personalization and optimization of the treatment plan for each cancer patient.

Association of TGF-β1 and XPD polymorphisms with severe acute radiation-induced esophageal toxicity in locally advanced lung cancer patients treated with radiotherapy

PURPOSE

Radiation-induced esophageal toxicity (RIET) is a dose-limiting toxicity in lung cancer patients receiving radiotherapy. Accumulating evidence indicates that DNA repair and the cytokine pathways play essential roles in radiation-induced diseases. Genetic polymorphisms of genes in these pathways may affect gene function and/or gene expression and lead to different treatment-related esophageal toxicity.

MATERIALS AND METHODS

This study investigated the association of 21 polymorphisms in 14 genes, with the occurrence of ≥ grade 2 acute RIET. Genotypes were analyzed among 213 stage III lung cancer patients receiving radiotherapy.

RESULTS

We used Cox proportional hazard model to examine the effects of genotypes on ≥ grade 2 acute RIET risk and Kaplan-Meier estimator to compare effects of different genotypes on such risk. Multivariate analysis showed that CT or TT genotype of TGF-β1-509C/T polymorphism was associated with a significantly higher RIET risk (adjusted hazard ratio [HR]=2.47; 95% confidence interval (CI)=1.17-5.24; P=0.018, or HR=3.86; 95% CI=1.50-9.92; P=0.005), respectively, compared with the CC genotype. Moreover, Lys/Gln+Gln/Gln genotypes of XPD Lys751Gln polymorphism were also associated with a significantly decreased RIET risk (adjusted HR=0.55; 95% CI=0.32-0.96; P=0.030).

CONCLUSIONS

This report, for the first time, examined the influence of inherited variation in the DNA repair and the cytokine pathways on RIET.

Association of P53 and ATM polymorphisms with risk of radiation-induced pneumonitis in lung cancer patients treated with radiotherapy

PURPOSE

Radiation-induced pneumonitis (RP) is the most common dose-limiting complication in lung cancer patients treated with radiotherapy. Accumulating evidence indicates that P53 and the ataxia telangiectasia-mutated protein (ATM)-dependent signaling response cascade play a crucial role in radiation-induced diseases. Consistent with this, our previous study showed that a functional genetic ATM polymorphism was associated with increased RP risk.

METHODS AND MATERIALS

To evaluate the role of genetic P53 polymorphism in RP, we analyzed the P53 Arg72Pro polymorphism in a cohort including 253 lung cancer patients receiving thoracic irradiation.

RESULTS

We found that the P53 72Arg/Arg genotype was associated with increased RP risk compared with the 72Pro/Pro genotype. Furthermore, the P53 Arg72Pro and ATM -111G>A polymorphisms display an additive combination effect in intensifying the risk of developing RP. The cross-validation test showed that 63.2% of RP cases can be identified by P53 and ATM genotypes.

CONCLUSIONS

These results indicate that genetic polymorphisms in the ATM-P53 pathway influence susceptibility to RP and genotyping P53 and ATM polymorphisms might help to identify patients susceptible to developing RP when receiving radiotherapy.