Interplay between mutagen sensitivity and epidemiological factors in modulatinglung cancer risk

Correlation between allergic rhinitis or hay fever and lung cancer: A systematic review and meta-analysis

BACKGROUND

The association between allergies and cancer is contradictory, whereas some forms of cancer have inverse associations with allergies. Allergic rhinitis (AR) is the most prevalent form of allergy, and lung cancer is one of the most prevalent forms of cancer with the highest mortality rate. Recent studies have reported a positive association between asthma and lung cancer; however, this association is inconclusive. Furthermore, AR is positively associated with asthma; therefore, our research question was to explore whether there is any correlation between AR and lung cancer epidemiologically.

METHODS

After a rigorous search of PubMed, Google Scholar, and ScienceDirect, 7 eligible articles were included in this systematic review and meta-analysis, including 4724 cases and 9059 controls, 5 from the USA, and one each from Canada and Germany.

RESULTS

Pooled analysis (OR, 0.55; 95% CI: 0.45-0.68; P value < .00001) showed a strong inverse relationship between AR and lung cancer.

CONCLUSION

The current meta-analysis suggests an inverse relationship between AR and lung cancer; however, new epidemiological studies are required to observe the current scenario more comprehensively.

DNA repair phenotype and cancer risk: a systematic review and meta-analysis of 55 case-control studies

DNA repair phenotype can be measured in blood and may be a potential biomarker of cancer risk. We conducted a systematic review and meta-analysis of epidemiological studies of DNA repair phenotype and cancer through March 2021. We used random-effects models to calculate pooled odds ratios (ORs) of cancer risk for those with the lowest DNA repair capacity compared with those with the highest capacity. We included 55 case–control studies that evaluated 12 different cancers using 10 different DNA repair assays. The pooled OR of cancer risk (all cancer types combined) was 2.92 (95% Confidence Interval (CI) 2.49, 3.43) for the lowest DNA repair. Lower DNA repair was associated with all studied cancer types, and pooled ORs (95% CI) ranged from 2.02 (1.43, 2.85) for skin cancer to 7.60 (3.26, 17.72) for liver cancer. All assays, except the homologous recombination repair assay, showed statistically significant associations with cancer. The effect size ranged from 1.90 (1.00, 3.60) for the etoposide-induced double-strand break assay to 5.06 (3.67, 6.99) for the γ-H2AX assay. The consistency and strength of the associations support the use of these phenotypic biomarkers; however large-scale prospective studies will be important for understanding their use related to age and screening initiation.

Association between previous lung diseases and lung cancer risk: a systematic review and meta-analysis

Previous lung diseases (PLD) are known risk factors for lung cancer. However, it remains unclear how the association varies by lung cancer subtype and socio-demographic characteristics. We conducted a systematic literature search in three electronic databases from the inception of each database up until 13 January 2021. A total of 73 studies (18 cohort and 55 case-control studies) consisting of 97,322 cases and 7,761,702 controls were included. Heterogeneity was assessed using the I 2 statistic. Based on the heterogeneity, either the fixed-effects or random-effects model was used to estimate the pooled summary estimate (PSE) and 95% confidence interval (CI) for the association between PLD and lung cancer risk. A history of asthma, chronic bronchitis, emphysema, pneumonia, tuberculosis, and COPD was associated with higher lung cancer risk, with a history of COPD and emphysema having at least two-fold relative risk. A history of hay fever was associated with lower lung cancer risk (PSE= 0.66, 95% CI= 0.54-0.81), even among ever-smokers (PSE= 0.55, 95% CI= 0.41-0.73). Older individuals with a history of asthma, chronic bronchitis, emphysema, COPD, or tuberculosis were associated with higher lung cancer risk. Individuals with a diagnosis of asthma, emphysema, or pneumonia within 1 to 10 years prior to lung cancer diagnosis were associated with higher lung cancer risk. Among ever-smokers, a history of COPD or emphysema have at least two-fold relative risk of lung cancer. PLD was associated with higher risk of lung cancer. Individuals with PLD should be closely monitored and prioritised for lung cancer screening.

Epidemiology of lung cancer: Diagnosis and management of lung cancer, 3rd ed: American College of Chest Physicians evidence-based clinical practice guidelines

BACKGROUND

Ever since a lung cancer epidemic emerged in the mid-1900 s, the epidemiology of lung cancer has been intensively investigated to characterize its causes and patterns of occurrence. This report summarizes the key findings of this research.

METHODS

A detailed literature search provided the basis for a narrative review, identifying and summarizing key reports on population patterns and factors that affect lung cancer risk.

RESULTS

Established environmental risk factors for lung cancer include smoking cigarettes and other tobacco products and exposure to secondhand tobacco smoke, occupational lung carcinogens, radiation, and indoor and outdoor air pollution. Cigarette smoking is the predominant cause of lung cancer and the leading worldwide cause of cancer death. Smoking prevalence in developing nations has increased, starting new lung cancer epidemics in these nations. A positive family history and acquired lung disease are examples of host factors that are clinically useful risk indicators. Risk prediction models based on lung cancer risk factors have been developed, but further refinement is needed to provide clinically useful risk stratification. Promising biomarkers of lung cancer risk and early detection have been identified, but none are ready for broad clinical application.

CONCLUSIONS

Almost all lung cancer deaths are caused by cigarette smoking, underscoring the need for ongoing efforts at tobacco control throughout the world. Further research is needed into the reasons underlying lung cancer disparities, the causes of lung cancer in never smokers, the potential role of HIV in lung carcinogenesis, and the development of biomarkers.

Risk assessment of esophageal adenocarcinoma using γ-H2AX assay

BACKGROUND

Mutagen-induced DNA damage as measured in peripheral blood lymphocytes (PBL) has been associated with increased risks of cancers. The formation of γ-H2AX is an early cellular response to DNA double-strand breaks (DSB). We hypothesize that higher level of radiation-induced γ-H2AX in PBLs may be associated with an increased risk of esophageal adenocarcinoma.

METHODS

Laser scanning cytometer-based immunocytochemical method was used to measure baseline and irradiation-induced γ-H2AX levels in PBLs from 211 patients with esophageal adenocarcinoma and 211 healthy controls. The ratio of induced γ-H2AX level to baseline level was used to evaluate individual susceptibility to DSBs. Relative risks for esophageal adenocarcinoma associated with γ-H2AX were assessed by multivariable logistic regression analysis.

RESULTS

Radiation-induced γ-H2AX level and the γ-H2AX ratio were significantly higher in cases than in controls. Dichotomized at the median in controls, a significantly increased risk for esophageal adenocarcinoma was observed in association with high γ-H2AX ratio [OR = 2.94; 95% confidence interval (CI), 1.83-4.72]. Quartile analyses showed significant dose-response associations between higher γ-H2AX ratio and increased risk of esophageal adenocarcinoma (Ptrend, 1.64E-06). In addition, joint effect between γ-H2AX ratio and smoking was observed: smokers who had high γ-H2AX ratio exhibited the highest risk of esophageal adenocarcinoma (OR = 5.53; 95% CI, 2.71-11.25) compared with never smokers with low γ-H2AX ratio.

CONCLUSION

Radiation-induced DNA damage assessed by γ-H2AX ratio is associated with an increased risk of esophageal adenocarcinoma.

IMPACT

γ-H2AX assay is a new and robust method to measure DSB damage in PBLs, which can be used to assess mutagen sensitivity and esophageal adenocarcinoma risk.

Ionizing radiation-induced γ-H2AX activity in whole blood culture and the risk of lung cancer

BACKGROUND

Phenotypic biomarkers of DNA damage repair may enhance cancer risk prediction. The γ-H2AX formed at the sites of double-strand break (DSB) after ionizing radiation is a specific marker of DNA damage.

METHODS

In an ongoing case-control study, the baseline and ionizing radiation-induced γ-H2AX levels in peripheral blood lymphocytes (PBL) from frequency-matched 306 untreated patients with lung cancer and 306 controls were measured by a laser scanning cytometer-based immunocytochemical method. The ratio of ionizing radiation-induced γ-H2AX level to the baseline was used to evaluate interindividual variation of DSB damage response and to assess the risk of lung cancer by using unconditional multivariable logistic regression with adjustment of age, sex, ethnicity, smoking status, family history of lung cancer, dust exposure, and emphysema.

RESULTS

The mean γ-H2AX ratio was significantly higher in cases than controls (1.46 ± 0.14 vs. 1.41 ± 0.12, P < 0.001). Dichotomized at the median in controls, high γ-H2AX ratio was significantly associated with increased risk of lung cancer [OR = 2.43; 95% confidence interval (CI): 1.66-3.56]. There was also a significant dose-response relationship between γ-H2AX ratio and lung cancer risk in quartile analysis. Analysis of joint effects with other epidemiologic risk factors revealed elevated risk with increasing number of risk factors.

CONCLUSION

γ-H2AX activity as shown by measuring DSB damage in ionizing radiation-irradiated PBLs may be a novel phenotypic marker of lung cancer risk.

IMPACT

γ-H2AX assay is a robust and quantifiable image-based cytometer method that measures mutagen-induced DSB response in PBLs as a potential biomarker in lung cancer risk assessment.

DNA damage response in monozygotic twins discordant for smoking habits

Previous studies in twins indicate that non-shared environment, beyond genetic factors, contributes substantially to individual variation in mutagen sensitivity; however, the role of specific causative factors (e.g. tobacco smoke, diet) was not elucidated. In this investigation, a population of 22 couples of monozygotic twins with discordant smoking habits was selected with the aim of evaluating the influence of tobacco smoke on individual response to DNA damage. The study design virtually eliminated the contribution of genetic heterogeneity to the intra-pair variation in DNA damage response, and thus any difference in the end-points investigated could directly be attributed to the non-shared environment experienced by co-twins, which included as main factor cigarette smoke exposure. Peripheral lymphocytes of study subjects were challenged ex vivo with γ-rays, and the induction, processing, fixation of DNA damage evaluated through multiple approaches. Folate status of study subjects was considered significant covariate since it is affected by smoking habits and can influence radiosensitivity. Similar responses were elicited by γ-rays in co-twins for all the end-points analysed, despite their discordant smoking habits. Folate status did not modify DNA damage response, even though a combined effect of smoking habits, low-plasma folic acid level, and ionising radiation was observed on apoptosis. A possible modulation of DNA damage response by duration and intensity of tobacco smoke exposure was suggested by Comet assay and micronucleus data, but the effect was quantitatively limited. Overall, the results obtained indicate that differences in smoking habits do not contribute to a large extent to inter-individual variability in the response to radiation-induced DNA damage observed in healthy human populations.

[Comparative analysis of clinical features of lung cancer in west China hospital in 2000 and 2010]

背景与目的

原发性支气管肺癌是最常见的恶性肿瘤之一，本研究旨在回顾性分析2000年与2010年四川大学华西医院原发性支气管肺癌临床特征的变化，为肺癌的早期诊断和治疗提供参考。

方法

收集2000年与2010年在四川大学华西医院住院的四川地区常住人口中初诊原发性支气管肺癌病例，对两组患者的主要就诊原因、发病到就诊时间、伴随基础疾病、合并肺癌的双原发癌、家族恶性肿瘤史、肿瘤位置、分化程度、肿瘤分期及首诊主要治疗方式等临床资料进行对比分析。

结果

收集有细胞学或组织学依据的肺癌病例共2, 167例，其中2000年616例，2010年1, 551例。10年中因体检而就诊的肺癌患者构成比上升（5.2% vs 16.7%, P < 0.001），肺癌患者发病到就诊时间缩短（P < 0.001），伴家族恶性肿瘤史的肺癌患者增多（3.9% vs 13.7%, P < 0.001）；鳞癌低分化癌构成比明显增加（59.4% vs 76.7%, P=0.002），而腺癌低分化癌构成比明显减少（72.3% vs 51.8%, P=0.002）；非小细胞肺癌患者Ⅰa期及Ⅳ期构成比明显上升（Ⅰa期：1.0% vs 4.5%, P < 0.001; Ⅳ期：30.4% vs 37.8%, P < 0.001），Ⅲa期构成比明显下降（26.6% vs 14.8%, P=0.002）；治疗上非小细胞肺癌患者首诊采取化疗构成比上升（35.9% vs 42.4%, P=0.007），Ⅲa期首诊采取手术者明显上升（41.8% vs 63.4%, P=0.002），Ⅳ期首诊采取手术者明显下降（9.4% vs 3.1%, P=0.001），小细胞肺癌患者首诊采取手术者明显下降（30.4% vs 4.3%, P < 0.001）。

结论

近十年肺癌患者的临床特征部分已产生了较为明显的变化，根据这些变化选择更适合的预防、诊断和治疗措施对降低肺癌发病率、提高生存率有一定意义。

DNA repair: from genome maintenance to biomarker and therapeutic target

A critical link exists between an individual's ability to repair cellular DNA damage and cancer development, progression, and response to therapy. Knowledge gained about the proteins involved and types of damage repaired by the individual DNA repair pathways has led to the development of a variety of assays aimed at determining an individual's DNA repair capacity. These assays and their use in the analysis of clinical samples have yielded useful though somewhat conflicting data. In this review article, we discuss the major DNA repair pathways, the proteins and genes required for each, assays used to analyze activity, and the relevant clinical studies to date. With the recent results from clinical trials targeting specific DNA repair proteins for the treatment of cancer, accurate, reproducible, and relevant analysis of DNA repair takes on an even greater significance. We highlight the strengths and limitations of these DNA repair studies and assays, with respect to the clinical assessment of DNA repair capacity to determine cancer development and response to therapy.

Evaluating the effects of genetic variants of DNA repair genes using cytogenetic mutagen sensitivity approaches

Mutagen sensitivity, measured in short-term cultures of peripheral blood lymphocytes by cytogenetic endpoints, is an indirect measure for DNA repair capacity and has been used for many years as a biomarker for intrinsic susceptibility for cancer. In this article, we briefly give an overview of the different cytogenetic mutagen sensitivity approaches that have been used successfully to evaluate the biological effects of polymorphisms in DNA repair genes based on a current review of the literature and based on the need for biomarkers that would allow the characterization of the biological and functional significance of such polymorphisms. We also address some of the future challenges facing this emerging area of research.

[A case-control study on non-smoking primary lung cancers in Sichuan, China]

BACKGROUND AND OBJECTIVE

The incidence of lung cancer in non-smokers is increasing in recent years. The aim of this investigation is to explore main risk factors of non-smoking primary lung cancers in Sichuan province in order to provide more accurate data for clinical.

METHODS

One hundred and fourty-five non-smoking pairs of cases and 145 of controls were matched by age and sex. The patients were newly-diagnosed definitely as primary lung cancer at West China Hospital of Sichuan University from March to December 2009.

RESULTS

Seventeen exposure factors were explored as epidemic agents for non-smoking lung cancer in Sichuan by using univariate analysis; mutivariate conditional Logistic regression analysis showed that passive smoking, moved into newly renovated homes over the past 10 years, family cancer history from second/ third-degree relatives, lack of emotion regulation, heavy work pressure and poor quality of sleep were main risk agents for the non-smoking lung cancer incidence with OR 2.267 (95% CI: 1.231-4.177), 5.080 (95% CI: 1.632-15.817), 7.937 (95% CI: 1.815-34.705), 2.491 (95% CI: 1.230-4.738), 5.769 (95% CI: 2.030-16.396), 2.538 (95% CI: 1.277-4.861), respectively. While higher body mass index, eating fruit and vegetable and regular participating in physical exercise might be protective factors with OR 0.419 (95% CI: 0.226-0.779), 0.344 (95% CI: 0.155-0.762), 0.507 (95% CI: 0.274-0.937), respectively.

CONCLUSION

The occurrence of non-smoking primary lung cancer associated with a variety of exposure factors including passive smoking, history of exposure to harmful environmental, family cancer history, mental and psychological factors in Sichuan Province.

Genetic polymorphisms in DNA repair genes as modulators of Hodgkin disease risk

BACKGROUND

Although the pathogenesis of Hodgkin disease (HD) remains unknown, the results of epidemiologic studies suggest that heritable factors are important in terms of susceptibility. Polymorphisms in DNA repair genes may contribute to individual susceptibility for development of different cancers. However, to the authors' knowledge, few studies to date have investigated the role of such polymorphisms as risk factors for development of HD.

METHODS

The authors evaluated the relation between polymorphisms in 3 nucleotide excision repair pathway genes (XPD [Lys751Gln], XPC [Lys939Gln], and XPG [Asp1104His]), the base excision repair XRCC1 (Arg399Gln), and double-strand break repair XRCC3 (Thr241Met) in a population of 200 HD cases and 220 matched controls. Variants were investigated independently and in combination; odd ratios (OR) were calculated.

RESULTS

A positive association was found for XRCC1 gene polymorphism Arg399Gln (OR, 1.77; 95% confidence interval [95% CI], 1.16-2.71) and risk of HD. The combined analysis demonstrated that XRCC1/XRCC3 and XRCC1/XPC polymorphisms were associated with a significant increase in HD risk. XRCC1 Arg/Arg and XRCC3 Thr/Met genotypes combined were associated with an OR of 2.38 (95% CI, 1.24-4.55). The XRCC1 Arg/Gln and XRCC3 Thr/Thr, Thr/Met, and Met/Met genotypes had ORs of 1.88 (95% CI, 1.02-4.10), 1.97 (95% CI, 1.05-3.73), and 4.13 (95% CI, 1.50-11.33), respectively. XRCC1 Gln/Gln and XRCC3 Thr/Thr variant led to a significant increase in risk, with ORs of 3.00 (95% CI, 1.15-7.80). Similarly, XRCC1 Arg/Gln together with XPC Lys/Lys was found to significantly increase the risk of HD (OR, 2.14; 95% CI, 1.09-4.23).

CONCLUSIONS

These data suggest that genetic polymorphisms in DNA repair genes may modify the risk of HD, especially when interactions between the pathways are considered.

Correlates of susceptibility to smoking among Mexican origin youth residing in Houston, Texas: a cross-sectional analysis

Background

Survey data suggest that in Texas Latino youth exhibit higher rates of susceptibility to smoking than youth from other ethnic groups. In this analysis we examined the relationship between susceptibility to smoking and well-known risk factors associated with smoking initiation among a cohort of 11 to 13 year old Mexican origin youth residing in Houston, Texas.

Methods

We analyzed cross-sectional survey data from 1,187 participants who reported they had never smoked, even a puff of a cigarette. The survey assessed peer and family social influence, school and neighborhood characteristics, level of family acculturation and socioeconomic status, and attitudes toward smoking. Bivariate associations, Student's t-tests, and logistic regression analysis were used to examine predictors of susceptibility.

Results

Overall, 22.1% of the never-smokers were susceptible to smoking. Boys were more likely to be susceptible than girls (25.6% vs. 18.9%), and susceptible children were slightly older than non-susceptible children (12.1 vs. 11.8 years). In addition, multivariate analyses revealed that positive expectations about smoking exerted the strongest influence on susceptibility status (odds ratio = 4.85). Multivariate analyses further revealed that compared to non-susceptible participants, susceptibles were more likely to report peer influences supportive of smoking, lower subjective social status and more detentions at school, more temptations to try smoking and to have a mother and a brother who smokes.

Conclusion

Our findings suggest that interventions that target positive expectations about smoking may be useful in this population. Furthermore, because youth encounter smoking-initiation risk factors in different social environments, our results underscore the continued need for both family- and school-based primary prevention programs to adequately combat their influence. The results also can be used to inform the development of culturally sensitive programs for Mexican origin youth.

Smoking-related genomic signatures in non-small cell lung cancer

RATIONALE

Tobacco smoking is responsible for 85% of all lung cancers. To further our understanding of the molecular pathogenesis of lung cancer, we determined whether smoking history leads to the emergence of specific genomic alterations found in non-small cell lung cancer (NSCLC).

OBJECTIVES

To identify gene copy number alterations in NSCLCs associated with smoking history or DNA repair capacity.

METHODS

Seventy-five NSCLCs were selected for this study from patients with current, none, or past smoking history, including pack year information. Tissue sections were microdissected, and DNA was extracted, purified, and labeled by random priming before hybridization onto bacterial artificial chromosome (BAC) arrays. Normalized ratios were correlated with smoking history and DNA repair capacity was measured by an in vitro lymphocyte assay in the same patients.

MEASUREMENTS AND MAIN RESULTS

We identified smoking-related genomic signatures in NSCLCs that could be predicted with an overall 74% accuracy. Lung tumors arising from current-smokers had the greatest number of copy number alterations. The genomic regions most significantly associated with smoking were located within 60 regions and were functionally associated with genes controlling the M phase of the cell cycle, the segregation of chromosomes, and the methylation of DNA. Verification of the data is provided from data in the public domain and by quantitative real-time polymerase chain reaction. The associations between genomic abnormalities and DNA repair capacity did not reach statistical significance.

CONCLUSIONS

These findings indicate that smoking history leaves a specific genomic signature in the DNA of lung tumors and suggest that these alterations may reflect new molecular pathways to cancer development.

An expanded risk prediction model for lung cancer

Risk prediction models are useful in clinical decision making. We have published an internally validated prediction tool for lung cancer based on easily obtainable epidemiologic and clinical data. Because the precision of the model was modest, we now estimate the improvement obtained by adding two markers of DNA repair capacity. Assay data (host-cell reactivation and mutagen sensitivity) were available for 725 White lung cancer cases and 615 controls, all former or current smokers, a subset of cases and controls from the previous analysis. Multivariable models were constructed from the original variables with addition of the biomarkers separately and together. Pairwise comparisons of the area under the receiver operating characteristic curves (AUC) and 3-fold cross-validations were done. For former smokers, the AUC and 95% confidence intervals were 0.67 (0.63-0.71) for the baseline model and 0.70 (0.66-0.74) for the expanded model. For current smokers, the comparable AUC values were 0.68 (0.64-0.72) and 0.73 (0.69-0.77). For both groups, the expanded models were statistically significantly better than the baseline models (P = 0.006 and P = 0.0048, respectively), although the increases in the concordance statistics were modest. We also recomputed 1-year absolute risks of lung cancer as described previously for two different risk profiles and showed that individuals who exhibited poor repair capacity or heightened mutagen sensitivity had increased absolute risks of lung cancer. Addition of biomarker assays improved the sensitivity of the expanded models.

Automated detection of genetic abnormalities combined with cytology in sputum is a sensitive predictor of lung cancer

Detection of lung cancer by sputum cytology has low sensitivity but is noninvasive and, if improved, could be a powerful tool for early lung cancer detection. To evaluate whether the accuracy of diagnosing lung cancer by evaluating sputa for cytologic atypia and genetic abnormalities is greater than that of conventional cytology alone, automated scoring of genetic abnormalities for 3p22.1 and 10q22.3 (SP-A) by fluorescence in situ hybridization (FISH) and conventional cytology was done on sputa from 35 subjects with lung cancer, 25 high-risk smokers, and 6 healthy control subjects. Multivariate analysis was performed to select variables that most accurately predicted lung cancer. A model of probability for the presence of lung cancer was derived for each subject. Cells exfoliated from patients with lung cancer contained genetic aberrations and cytologic atypias at significantly higher levels than in those from control subjects. When combined with cytologic atypia, a model of risk for lung cancer was derived that had 74% sensitivity and 82% specificity to predict the presence of lung cancer, whereas conventional cytology achieved only 37% sensitivity and 87% specificity. For diagnosing lung cancer in sputum, a combination of molecular and cytologic variables was superior to using conventional cytology alone.

BPDE induced lymphocytic chromosome 3p deletions may predict renal cell carcinoma risk

PURPOSE

Cigarette smoking is a risk factor for renal cell carcinoma. BPDE (benzo[alpha]pyrene diol epoxide) (Midwest Research Institute, Kansas City, Missouri), which is a major constituent of cigarette smoke, induces 3p aberrations that are associated with susceptibility to other smoking associated cancers. Because chromosome 3p deletions are known to be the most frequent genetic alterations in renal cell carcinoma, we tested whether 3p sensitivity to BPDE predicts susceptibility to renal cell carcinoma.

MATERIALS AND METHODS

Cultured peripheral blood lymphocytic cells from 170 cases and 135 controls were treated with 2 microM BPDE for 24 hours and assessed for 3p deletions by fluorescence in situ hybridization using probes directed to 3p25.2, 3p21.3, 3p14.2 and 3p12.2. A probe for 3q13 served as a control. One thousand lymphocyte interphases were scored per sample.

RESULTS

At each locus BPDE induced 3p deletions were significantly more common in cases than in controls. No significant differences between cases and controls were observed for deletions in 3q13. Using the median value in controls as the cutoff point for BPDE sensitivity we found that the OR in subjects with high BPDE sensitivity at 3p25.2, 3p21.3, 3p14.2 and 3p12.2 was 2.02 (95% CI 1.18-3.46), 2.28 (95% CI 1.33-3.92), 1.84 (95% CI 1.07-3.16) and 1.97 (95% CI 1.15-3.37), respectively. There were dose dependent relationships between the number of deletions at each locus and the risk of renal cell carcinoma.

CONCLUSIONS

This study demonstrates that chromosome 3p may be a specific molecular target of cigarette carcinogens and BPDE sensitivity in chromosome 3p may reflect the genetic susceptibility of an individual to renal cell carcinoma.

Inherited susceptibility to bleomycin-induced micronuclei: correlating polymorphisms in GSTT1, GSTM1 and DNA repair genes with mutagen sensitivity

Susceptibility to DNA damage varies among individuals and sensitivity to bleomycin (BLM) may reflect the inter-individual differences. BLM sensitivity in part may be explained by inherited differences in DNA repair genes. We investigated the association between genetic polymorphisms in the GSTT1, GSTM1, XPD, XRCC1 and XRCC3 genes and the levels of spontaneous and BLM-induced DNA damage in peripheral blood lymphocytes from 200 healthy, unexposed individuals. The investigation of BLM sensitivity on cancer- or disease-free subjects and not occupationally exposed to known mutagen represents the strengths of the present study, as the detection of genetic damage is not biased by any disease- and occupational-related factor. The micronucleus (MN) assay was used to detect the spontaneous and BLM-induced genetic damage whereas, genotype analysis was carried out using methods based on polymerase chain reaction. Poisson regression analysis showed that subject's age, gender and smoking status had no effect on the spontaneous and BLM-induced MN frequencies. Genotype analysis revealed a clear association between GSTT1-null and XPD polymorphisms and both spontaneous and BLM-induced MN frequencies, whereas the effect of the XRCC1 polymorphism was marginally significant only with regard to spontaneous MN frequency. Genotype analysis did not reveal a clear association between the other studied SNPs (GSTM1 and XRCC3) and MN frequencies. Poisson regression analysis revealed no association between the score of protective alleles and the frequency of spontaneous MN. However, an increased number of protective alleles was significantly associated with a lower frequency of BLM-induced MN (P=0.0003). This finding highlights the genetic basis for BLM sensitivity, which could be a valid and useful surrogate for identifying genotypes that might increase susceptibility in population exposed to carcinogens. Further investigations in a large sample size and including more SNPs, reflecting the complexity of DNA repair machinery, might lead to the identification of a genetic profile responsible for the susceptibility to genotoxicants, with a far-reaching long-term impact on primary prevention and early detection of disease associated genes.

Mutagen sensitivity: a genetic predisposition factor for cancer

Mutagen sensitivity, measured by quantifying the chromatid breaks induced by mutagens in short-term cultures of peripheral blood lymphocytes, has been used as an indirect measure of DNA repair capacity. Numerous epidemiologic studies have suggested that mutagen sensitivity is a cancer susceptibility factor for a variety of epithelial cancers. A recent classic twin study examined systematically the role of genetic and environmental factors on the mutagen sensitivity phenotype and provided compelling evidence that mutagen sensitivity is highly heritable. A new prospective analysis provides further support to the notion that mutagen sensitivity increases the risk of cancer. In this review, we briefly summarize nearly two decades of epidemiologic and genetic studies linking mutagen sensitivity and cancer risk. The evidence is becoming increasingly convincing that mutagen sensitivity is a risk factor for cancer development.