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1.  Trends in prevalence of prognostic factors and survival in lung cancer patients from 1985 to 2004 at a tertiary care center 
Cancer detection and prevention  2008;32(2):101-108.
After a prolonged period of increasing rates of lung cancer incidence and mortality for both men and women, incidence and mortality rates are decreasing in men and stabilizing in women. The goal of this study was to assess changes over 20 years in the prevalence of known risk factors for lung cancer and to elucidate possible predictors associated with lung cancer survival.
The study included a total of 908 patients with primary lung cancer referred to The University of Texas M. D. Anderson Cancer Center over three study periods 1985–1989 (N=392), 1993–1997 (N= 216), and 2000–2004 (N= 300). Detailed questionnaires were used to collect information from the patients. Hazard ratios were estimated by fitting a Cox proportional hazards model. Using the Kaplan Meier method, survival in months was calculated up to 2 years from the date of diagnosis to achieve comparability in the three groups.
We observed a decrease in the proportion of patients who are current cigarette smokers and an increase in the proportion of patients who present with adenocarcinoma of the lung, are obese and patients who present with localized disease. We also found an increase in the number of patients who report a family history of lung cancer. The overall median survival duration has increased over the years from 12.0 months in 1985–1989 to 17.5 months in 2000–2004. Also, the probability of survival of patients who were alive at 2 years after diagnosis has also increased (26.5% in 1985–1989 to 40.8% in 2000–2004). Overall, women had a better median survival than men.
The results show that the demographic, histologic, clinical, and outcome variables of patients with lung cancer have changed over the past 20 years. Most important, the survival of patients with lung cancer has improved.
PMCID: PMC4287275  PMID: 18639390
Lung cancer survival; time-trends; predictors for lung cancer survival
2.  Associations of Menthol Use with Motivation and Confidence to Quit Smoking 
To examine associations of menthol cigarette use with motivation and confidence to quit smoking, and potential moderation by race, among adult current smokers (N = 1067; 85% White, 15% Black).
Regression analyses, adjusted for sociodemographics and tobacco dependence, examined associations of menthol use with motivation and confidence to quit smoking with and without an interaction term for race.
Main effects were not significant; however, there was a significant interaction for confidence to quit smoking (p = .02). Stratified analyses indicated that Black menthol users were more confident about quitting than Black non-menthol users (p = .01).
Given their relatively lower quit rates as cited in previous literature, Black menthol users appear overly confident about their ability to quit smoking.
PMCID: PMC3761418  PMID: 23985285
menthol; race; confidence and motivation to quit
3.  Using Haplotype Analysis to Elucidate Significant Associations between Genes and Hodgkin Lymphoma 
Leukemia research  2012;36(11):1359-1364.
In this study, we estimated the association between the inferred haplotypes in the inflammation, DNA repair, and folate pathways, and developed risk models for Hodgkin Lymphoma. The study population consisted of 200 Hodgkin Lymphoma cases and 220 controls. A susceptible association was observed on the XPC gene with Haplotype CT (rs2228001 and rs2228000), and a protective association was observed on the IL4R gene with Haplotype TCA (rs1805012, rs1805015, and rs1801275). These results can provide the necessary tools to identify high-risk individuals after validation in large data sets.
PMCID: PMC3449215  PMID: 22902050
Single Nucleotide Polymorphism; Haplotypes; Hodgkin lymphoma; DNA Repair; Inflammation
4.  Earlier Age of Onset of BRCA Mutation-Related Cancers in Subsequent Generations 
Cancer  2011;118(2):321-325.
Women who are diagnosed with a deleterious mutation in either breast cancer (BRCA) gene have a high risk of developing breast and ovarian cancers at young ages. In this study, the authors assessed age at diagnosis in 2 generations of families with known mutations to investigate for earlier onset in subsequent generations.
Of the 132 BRCA-positive women with breast cancer who participated in a high-risk protocol at The University of Texas MD Anderson Cancer Center (Gen 2), 106 women could be paired with a family member in the previous generation (Gen 1) who was diagnosed with a BRCA-related cancer (either breast cancer or ovarian cancer). Age at diagnosis, location of the mutation, and year of birth were recorded. A previously published parametric anticipation model was applied in these genetically predisposed families.
The median age of cancer diagnosis was 42 years (range, 28–55 years) in Gen 2 and 48 years (range, 30–72 years) in Gen 1 (P < .001). In the parametric model, the estimated change in the expected age at onset for the entire cohort was 7.9 years (P < .0001). Statistically significant earlier ages at diagnosis also were observed within subgroups of BRCA1 and BRCA2 mutations, maternal inheritance, paternal inheritance, breast cancer only, and breast cancer-identified and ovarian cancer-identified families.
Breast and ovarian cancers in BRCA mutation carriers appeared to be diagnosed at an earlier age in later generations. The authors concluded that patients who are younger at the onset of BRCA-related cancers should continue to be tracked to offer appropriate screening modalities at appropriate ages.
PMCID: PMC4369377  PMID: 21913181
breast cancer; BRCA1; BRCA2; anticipation; hereditary breast and ovarian cancer syndrome
5.  Maternal current smoking: Concordance between adolescent proxy and mother’s self-report 
Nicotine & Tobacco Research  2009;11(8):1016-1019.
The purpose of this study was to examine the extent to which adolescent reports on mother’s smoking status and mother’s self-reports on smoking are concordant with one another.
Mothers self-reported on their smoking at two timepoints (first query and second query), while the adolescents reported on their mother’s smoking status at one timepoint. Kappa values and percent exact agreement as well as sensitivity and specificity were calculated to examine the degree of agreement between child and mother’s reports at the two timepoints.
Overall, the results indicated good concordance between mothers’ self-reports and adolescent reports on smoking. Specifically, higher concordance was observed for mother’s first query compared with mother’s second query (Κ = 0.69 vs. Κ = 0.51). Younger adolescents and girls provided more concordant reports than older adolescents and boys.
The results indicate that adolescent reports on mothers’ smoking behavior can be used as a proxy to obtain data if mothers’ self-report data are not available. Our results further suggest that when reports are not collected concurrently, self-report data obtained from the mothers prior to the proxy report obtained from her adolescent may be more reliable than the other way around.
PMCID: PMC2711984  PMID: 19531668
6.  Development and Validation of a Lung Cancer Risk Prediction Model for African-Americans 
Because existing risk prediction models for lung cancer were developed in white populations, they may not be appropriate for predicting risk among African-Americans. Therefore, a need exists to construct and validate a risk prediction model for lung cancer that is specific to African-Americans. We analyzed data from 491 African-Americans with lung cancer and 497 matched African-American controls to identify specific risks and incorporate them into a multivariable risk model for lung cancer and estimate the 5-year absolute risk of lung cancer. We performed internal and external validations of the risk model using data on additional cases and controls from the same ongoing multiracial/ethnic lung cancer case-control study from which the model-building data were obtained as well as data from two different lung cancer studies in metropolitan Detroit, respectively. We also compared our African-American model with our previously developed risk prediction model for whites. The final risk model included smoking-related variables [smoking status, pack-years smoked, age at smoking cessation (former smokers), and number of years since smoking cessation (former smokers)], self- reported physician diagnoses of chronic obstructive pulmonary disease or hay fever, and exposures to asbestos or wood dusts. Our risk prediction model for African-Americans exhibited good discrimination [75% (95% confidence interval, 0.67−0.82)] for our internal data and moderate discrimination [63% (95% confidence interval, 0.57−0.69)] for the external data group, which is an improvement over the Spitz model for white subjects. Existing lung cancer prediction models may not be appropriate for predicting risk for African-Americans because (a) they were developed using white populations, (b) level of risk is different for risk factors that African-American share with whites, and (c) unique group-specific risk factors exist for African-Americans. This study developed and validated a risk prediction model for lung cancer that is specific to African-Americans and thus more precise in predicting their risks. These findings highlight the importance of conducting further ethnic-specific analyses of disease risk.
PMCID: PMC2854402  PMID: 19138969
7.  Self-Reported Prior Lung Diseases as Risk Factors for Non-small Cell Lung Cancer in Mexican Americans 
This study was conducted to assess the association between prior history of respiratory disease and lung cancer among Mexican Americans using data from a multi-racial/ethnic lung cancer case–control study. Cases (n = 204) were patients with previously untreated lung cancer. Healthy control participants (n = 325) were recruited from a large physician group practice. Demographics, cigarette use, and history of respiratory disease were collected. Multivariable logistic regression models were used to estimate relative risk. Prior history of COPD (OR = 2.0; 95 % CI 1.2–3.3) and pneumonia (OR = 2.2; 95 % CI 1.3–3.6) were associated with an increased risk of lung cancer. These findings illustrate that prior COPD and pneumonia are associated with an increased risk of lung cancer among Mexican Americans. To our knowledge, this is one of largest case–control analyses assessing the role of respiratory disease and lung cancer risk specifically among Mexican-Americans.
PMCID: PMC3919532  PMID: 22847640
Lung diseases; Mexican Americans; Case–control studies; Epidemiology; Lung cancer
8.  Comparison of Attitudes Regarding Preimplantation Genetic Diagnosis Among Patients with Hereditary Cancer Syndromes 
Familial cancer  2014;13(2):291-299.
Preimplantation Genetic Diagnosis (PGD) allows couples to avoid having a child with an inherited condition, potentially reducing cancer burden in families with a hereditary cancer predisposition. This study investigated awareness and acceptance of PGD among patients with hereditary cancer syndromes.
Questionnaires were mailed to 984 adults with hereditary breast and ovarian cancer, Lynch syndrome, familial adenomatous polyposis, or multiple endocrine neoplasia type 1 or 2. Associations between clinical, demographic, and psychosocial factors and awareness and acceptance of PGD were examined.
Of 370 respondents (38% return rate), 28% felt their syndrome impacted family planning, 24% were aware of PGD, 72% felt that PGD should be offered, 43% would consider using PGD, and 29% were uncertain. Family experience and syndrome-specific characteristics, such as disease severity, quality of life and availability of medical interventions as well as gender, family planning stage, and religiosity impact perceptions of the acceptability of PGD, though a high level of uncertainty exists.
Hereditary cancer patients' opinions about the acceptability of PGD are similar to those of genetics and ethical experts. Patients should be told about PGD given that most had not heard of PGD, but feel that PGD should be offered.
PMCID: PMC4159051  PMID: 24072553
Preimplantation genetic diagnosis; hereditary cancer syndromes; hereditary breast and ovarian cancer; Lynch syndrome; familial adenomatous polyposis; multiple endocrine neoplasia
9.  Suppression of Akt-mTOR Pathway-A Novel Component of Oncogene Induced DNA Damage Response Barrier in Breast Tumorigenesis 
PLoS ONE  2014;9(5):e97076.
DNA damage has been thought to be directly associated with the neoplastic progression by enabling mutations in tumor suppressor genes and activating/and amplifying oncogenes ultimately resulting in genomic instability. DNA damage causes activation of the DNA damage response (DDR) that is an important cellular mechanism for maintaining genomic integrity in the face of genotoxic stress. While the cellular response to genotoxic stress has been extensively studied in cancer models, less is known about the cellular response to oncogenic stress in the premalignant context. In the present study, by using breast tissues samples from women at different risk levels for invasive breast cancer (normal, proliferative breast disease and ductal carcinoma in situ) we found that DNA damage is inversely correlated with risk of invasive breast cancer. Similarly, in MCF10A based in vitro model system where we recapitulated high DNA damage conditions as seen in patient samples by stably cloning in cyclin E, we found that high levels of oncogene induced DNA damage, by triggering inhibition of a major proliferative pathway (AKT), inhibits cell growth and causes cells to die through autophagy. These data suggest that AKT-mTOR pathway is a novel component of oncogene induced DNA damage response in immortalized ‘normal-like’ breast cells and its suppression may contribute to growth arrest and arrest of the breast tumorigenesis.
PMCID: PMC4014598  PMID: 24811059
10.  Self-Rated Health Among Adult Women of Mexican Origin 
Self-rated health (SRH), a consistent predictor of mortality among diverse populations, is sensitive to health indicators and social factors. American-born Hispanics report better SRH than their foreign-born counterparts but simultaneously report poorer health indicators and have shorter life expectancy. Using a matched prospective cross-sectional design, we analyzed data from 631 age-matched pairs of women, born in the United States or Mexico, enrolled in a cohort study based in Houston, Texas. Our first goal was to describe the relationships between SRH and health behaviors, physician-diagnosed chronic conditions, acculturation, and socioeconomic status (SES) by birthplace. Our second goal was to investigate the relative influence of SES, acculturation, health behaviors, and physician-diagnosed conditions in explaining expected differences in SRH between the two groups. Number of chronic conditions reported, particularly depression, more strongly influenced SRH than SES, acculturation, or reported health risk behaviors and the influence of birthplace is accounted for by these factors.
PMCID: PMC3940416  PMID: 24600161
Self-rated health; acculturation; SES; health indicators
11.  Variants in inflammation genes are implicated in risk of lung cancer in never smokers exposed to second-hand smoke 
Cancer discovery  2011;1(5):420-429.
Lung cancer in lifetime never smokers is distinct from that in smokers, but the role of separate or overlapping carcinogenic pathways has not been explored. We therefore evaluated a comprehensive panel of 11,737 SNPs in inflammatory-pathway genes in a discovery phase (451 lung cancer cases, 508 controls from Texas). SNPs that were significant were evaluated in a second external population (303 cases, 311 controls from the Mayo Clinic). An intronic SNP in the ACVR1B gene, rs12809597, was replicated with significance and restricted to those reporting adult exposure to environmental tobacco smoke Another promising candidate was a SNP in NR4A1, although the replication OR did not achieve statistical significance. ACVR1B belongs to the TGFR-β superfamily, contributing to resolution of inflammation and initiation of airway remodeling. An inflammatory microenvironment, (second hand smoking, asthma, or hay fever) is necessary for risk from these gene variants to be expressed. These findings require further replication, followed by targeted resequencing, and functional validation.
PMCID: PMC3919666  PMID: 22586632
lung cancer; never smokers; inflammation genes; sidestream exposure
12.  Genetic variants in the cell cycle control pathways contribute to early onset colorectal cancer in Lynch syndrome 
Cancer causes & control : CCC  2009;20(9):1769-1777.
Lynch syndrome is an autosomal dominant syndrome of familial malignancies resulting from germ-line mutations in DNA mismatch repair (MMR) genes. Our goal was to take a pathway-based approach to investigate the influence of polymorphisms in cell-cycle related genes on age of onset for Lynch syndrome using a tree-model.
Experimental Design
We evaluated polymorphisms in a panel of cell-cycle related genes (AURKA, CDKN2A, TP53, E2F2, CCND1, TP73, MDM2, IGF1 and CDKN2B) in 220 MMR gene mutation carriers from 129 families. We applied a novel statistical approach, tree-modeling (Classification and Regression Tree), to the analysis of data on Lynch syndrome patients to identify individuals with a higher probability of developing colorectal cancer at an early age and explore the gene-gene interactions between polymorphisms in cell-cycle genes.
We found that the subgroup with CDKN2A C580T wild-type genotype, IGF1 CA-repeats ≥19, E2F2 variant genotype, AURKA wild-type genotype, and CCND1 variant genotype had the youngest age of onset, with a 45-year median onset age. While the subgroup with CDKN2A C580T wild-type genotype, IGF1 CA-repeats ≥19, E2F2 wild-type genotype and AURKA variant genotype had the latest median age of onset, which was 70 years. Furthermore, we found evidence of a possible gene-gene interaction between E2F2 and AURKA genes related to CRC age of onset.
Polymorphisms in these cell-cycle related genes work together to modify the age at onset of CRC in patients with Lynch syndrome. These studies provide an important part of the foundation for development of a model for stratifying age of onset risk among those with Lynch syndrome.
PMCID: PMC3917505  PMID: 19690970
Tree model; cell cycle pathway; Polymorphisms; Lynch syndrome; Age of onset
13.  A Novel Approach to Exploring Potential Interactions among Single-Nucleotide Polymorphisms of Inflammation Genes in Gliomagenesis: An Exploratory Case-Only Study 
Despite extensive research on the topic, glioma etiology remains largely unknown. Exploration of potential interactions between single-nucleotide polymorphisms (SNPs) of immune genes is a promising new area of glioma research. The case-only study design is a powerful and efficient design for exploring possible multiplicative interactions between factors that are independent of one another. The purpose of our study was to use this exploratory design to identify potential pair wise SNP-SNP interactions from genes involved in several different immune-related pathways for investigation in future studies.
The study population consisted of two case groups: 1224 histological-confirmed, non-Hispanic white glioma cases from the U.S. and a validation population of 634 glioma cases from the U.K. Polytomous logistic regression, in which one SNP was coded as the outcome and the other SNP was included as the exposure, was utilized to calculate the odds ratios of the likelihood of cases simultaneously having the variant alleles of two different SNPs. Potential interactions were examined only between SNPs located in different genes or chromosomes.
Using this data-mining strategy, we found 396 significant SNP-SNP interactions among polymorphisms of immune-related genes that were present in both the U.S. and U.K. study populations.
This exploratory study was conducted for the purpose of hypothesis generation, and thus has provided several new hypotheses that can be tested using traditional case-control study designs to obtain estimates of risk.
This is the first study, to our knowledge, to take this novel approach to identifying SNP-SNP interactions relevant to glioma etiology.
PMCID: PMC3904785  PMID: 21724854
14.  Use of the Cytokinesis-Blocked Micronucleus Assay (CBMN) to Detect Gender Differences and Genetic Instability in a Lung Cancer Case-Control Study 
Although tobacco exposure is the predominant risk factor for lung cancer, other environmental agents are established lung carcinogens. Measuring the genotoxic effect of environmental exposures remains equivocal as increases in morbidity and mortality may be attributed to co-exposures such as smoking.
We evaluated genetic instability and risk of lung cancer associated with exposure to environmental agents (e.g., exhaust) and smoking among 500 lung cancer cases and 500 controls using the Cytokinesis-Blocked Micronucleus (CBMN) assay. Linear regression was applied to estimate the adjusted means of the CBMN endpoints (micronuclei and nucleoplasmic bridges). Logistic regression analyses were used to estimate lung cancer risk and to control for potential confounding by age, gender, and smoking.
Cases showed significantly higher levels of micronuclei and nucleoplasmic bridges as compared to controls (mean ± SEM=3.54±0.04 vs.1.81 ±0.04 and mean ± SEM=4.26±0.03 vs. 0.99±0.03, respectively; p <0.001) with no differences among participants with or without reported environmental exposure. No differences were observed when stratified by smoking or environmental exposure among cases or controls. A difference in lung cancer risk was observed between non-exposed male and female heavy smokers, although it was not statistically significant (I2=64.9%; P-value for Q statistic=0.09).
Our study confirms that the CBMN assay is an accurate predictor of lung cancer and supports the premise that heavy smoking may have an effect on DNA repair capacity and in turn modulate the risk of lung cancer.
Identifying factors that increase lung cancer risk may lead to more effective prevention measures.
PMCID: PMC3538922  PMID: 23195992
Lung cancer; CBMN assay; DNA damage; gender differences
15.  Genetic Variation in the PNPLA3 Gene and Hepatocellular Carcinoma in USA: Risk and Prognosis Prediction 
Molecular carcinogenesis  2013;52(0):10.1002/mc.22057.
Nonalcoholic fatty liver disease (NAFLD) is an emerging epidemic with high prevalence in Western countries. Genome-wide association studies had reported that a variation in the patatin-like phospholipase domain containing 3 (PNPLA3) gene is associated with high susceptibility to NAFLD. However, the relationship between this variation and hepatocellular carcinoma (HCC) has not been well established. We investigated the impact of PNPLA3 genetic variation (rs738409: C>G) on HCC risk and prognosis in the United States by conducting a case–control study that included 257 newly diagnosed and pathologically confirmed Caucasian patients with HCC (cases) and 494 healthy controls. Multivariate logistics and Cox regression models were used to control for the confounding effects of HCC risk and prognostic factors. We observed higher risk of HCC for subjects with a homozygous GG genotype than for those with CC or CG genotypes, the adjusted odds ratio (OR) was 3.21 (95% confidence interval [CI], 1.68–6.41). We observed risk modification among individuals with diabetes mellitus (OR = 19.11; 95% CI, 5.13–71.20). The PNPLA3 GG genotype was significantly associated with underlying cirrhosis in HCC patients (OR = 2.48; 95% CI, 1.05–5.87). Moreover, GG allele represents an independent risk factor for death. The adjusted hazard ratio of the GG genotype was 2.11 (95% CI, 1.26–3.52) compared with CC and CG genotypes. PNPLA3 genetic variation (rs738409: C>G) may determine individual susceptibility to HCC development and poor prognosis. Further experimental investigations are necessary for thorough assessment of the hepatocarcinogenic role of PNPLA3.
PMCID: PMC3808509  PMID: 23776098
molecular epidemiology; genetic susceptibility; case–control; single nucleotide polymorphism
16.  Increased risk of lung cancer in individuals with a family history of the disease: A pooled analysis from the International Lung Cancer Consortium 
Background and Methods
Familial aggregation of lung cancer exists after accounting for cigarette smoking. However, the extent to which family history affects risk by smoking status, histology, relative type and ethnicity is not well described. This pooled analysis included 24 case-control studies in the International Lung Cancer Consortium. Each study collected age of onset/interview, gender, race/ethnicity, cigarette smoking, histology and first-degree family history of lung cancer. Data from 24,380 lung cancer cases and 23,305 healthy controls were analyzed. Unconditional logistic regression models and generalized estimating equations were used to estimate odds ratios and 95% confidence intervals.
Individuals with a first-degree relative with lung cancer had a 1.51-fold increase in risk of lung cancer, after adjustment for smoking and other potential confounders(95% CI: 1.39, 1.63). The association was strongest for those with a family history in a sibling, after adjustment (OR=1.82, 95% CI: 1.62, 2.05). No modifying effect by histologic type was found. Never smokers showed a lower association with positive familial history of lung cancer (OR=1.25, 95% CI: 1.03, 1.52), slightly stronger for those with an affected sibling (OR=1.44, 95% CI: 1.07, 1.93), after adjustment.
The increased risk among never smokers and similar magnitudes of the effect of family history on lung cancer risk across histological types suggests familial aggregation of lung cancer is independent of those associated with cigarette smoking. While the role of genetic variation in the etiology of lung cancer remains to be fully characterized, family history assessment is immediately available and those with a positive history represent a higher risk group.
PMCID: PMC3445438  PMID: 22436981
17.  Genetic variants in the PI3K/PTEN/AKT/MTOR pathway predict head and neck cancer patient second primary tumor/recurrence risk and response to retinoid chemoprevention 
Clinical Cancer Research  2012;18(13):3705-3713.
The development of second primary tumors (SPT) or recurrence alters prognosis for curatively-treated head and neck squamous cell carcinoma (HNSCC) patients. 13-cis-retnoic acid (13-cRA) has been tested as a chemoprevention agent in clinical trials with mixed results. Therefore, we investigated if genetic variants in the PI3K/PTEN/AKT/MTOR pathway could serve as biomarkers to identify which patients are at high risk of an SPT/recurrence while also predicting response to 13-cRA chemoprevention.
Experimental Design
A total of 137 pathway SNPs were genotyped in 440 patients from the Retinoid Head and Neck Second Primary Trial and assessed for SPT/recurrence risk and response to 13-cRA. Risk models were created based on epidemiology, clinical, and genetic data.
Twenty-two genetic loci were associated with increased SPT/recurrence risk with six also being associated with a significant benefit following chemoprevention. Combined analysis of these high-risk/high-benefit loci identified a significant (P = 1.54×10−4) dose-response relationship for SPT/recurrence risk, with patients carrying 4–5 high-risk genotypes having a 3.76-fold (95%CI:1.87–7.57) increase in risk in the placebo group (n=215). Patients carrying 4–5 high-risk loci showed the most benefit from 13-cRA chemoprevention with a 73% reduction in SPT/recurrence (95%CI:0.13–0.58) compared to those with the same number of high-risk genotypes who were randomized to receive placebo. Incorporation of these loci into a risk model significantly improved the discriminatory ability over models with epidemiology, clinical, and previously identified genetic variables.
These results demonstrate that loci within this important pathway could identify individuals with a high-risk/high-benefit profile and are a step towards personalized chemoprevention for HNSCC patients.
PMCID: PMC3404728  PMID: 22577058
18.  Cigarette Experimentation in Mexican Origin Youth: Psychosocial and Genetic Determinants 
Established psychosocial risk factors increase the risk for experimentation among Mexican-origin youth. Now we comprehensively investigate the added contribution of select polymorphisms in candidate genetic pathways associated with sensation seeking, risk taking, and smoking phenotypes to predict experimentation.
Participants, (N=1,118 Mexican origin youth) recruited from a large population-based cohort study in Houston, Texas, provided prospective data on cigarette experimentation over three years. Psychosocial data were elicited twice—baseline and final follow-up. Participants were genotyped for 672 functional and tagging variants in the dopamine, serotonin and opioid pathways.
After adjusting for gender and age, with a Bayesian False Discovery Probability set at 0.8 and prior probability of 0.05, six gene variants were significantly associated with risk of experimentation. After controlling for established risk factors, multivariable analyses revealed that participants with six or more risk alleles were 2.25 (95%CI: 1.62–3.13) times more likely to have experimented since baseline compared to participants with five or fewer. Among committed never smokers (N=872), three genes (OPRM1, SNAP25, HTR1B) were associated with experimentation as were all psychosocial factors. Among susceptible youth (N=246) older age at baseline, living with a smoker, and three different genes (HTR2A, DRD2, SLC6A3) predicted experimentation.
Our findings, which have implications for development of culturally-specific interventions, need to be validated in other ethnic groups.
These results suggest that variations in select genes interact with a cognitive predisposition toward smoking. In susceptible adolescents, the impact of the genetic variants appears to be larger compared to committed never smokers.
PMCID: PMC3382046  PMID: 22028400
19.  Multistage analysis of variants in the Inflammation pathway and lung cancer risk in smokers 
Tobacco-induced lung cancer is characterized by a deregulated inflammatory microenvironment. Variants in multiple genes in inflammation pathways may contribute to risk of lung cancer.
We therefore conducted a three-stage comprehensive pathway analysis (discovery, replication and meta-analysis) of inflammation gene variants in ever smoking lung cancer cases and controls. A discovery set (1096 cases; 727 controls) and an independent and non-overlapping internal replication set (1154 cases; 1137 controls) were derived from an ongoing case-control study. For discovery, we used an iSelect BeadChip to interrogate a comprehensive panel of 11737 inflammation pathway SNPs and selected nominally significant (p<0.05) SNPs for internal replication.
There were 6 SNPs that achieved statistical significance (p<0.05) in the internal replication dataset with concordant risk estimates for former smokers and 5 concordant and replicated SNPs in current smokers. Replicated hits were further tested in a subsequent meta-analysis using external data derived from two published GWAS and a case-control study. Two of these variants (a BCL2L14 SNP in former smokers and a SNP in IL2RB in current smokers) were further validated. In risk score analyses, there was a 26% increase in risk with each additional adverse allele when we combined the genotyped SNP and the most significant imputed SNP in IL2RB in current smokers and a 36% similar increase in risk for former smokers associated with genotyped and imputed BCL2L14 SNPs.
Before they can be applied for risk prediction efforts, these SNPs should be subject to further external replication and more extensive fine mapping studies.
PMCID: PMC3487592  PMID: 22573796
Inflammation SNPS; lung cancer; smokers
20.  Hodgkin Lymphoma Risk: Role of Genetic Polymorphisms and Gene-Gene Interactions in DNA repair pathways 
Molecular carcinogenesis  2011;50(11):825-834.
DNA repair variants may play a potentially important role in an individual’s susceptibility to developing cancer. Numerous studies have reported the association between genetic single nucleotide polymorphisms (SNPs) in DNA repair genes and different types of hematologic cancers. However, to date, the effects of such SNPs on modulating Hodgkin Lymphoma (HL) risk have not yet been investigated. We hypothesized that gene-gene interaction between candidate genes in Direct Reversal, Nucleotide excision repair (NER), Base excision repair (BER) and Double strand break (DSB) pathways may contribute to susceptibility to HL. To test this hypothesis, we conducted a study on 200 HL cases and 220 controls to assess associations between HL risk and 21 functional SNPs in DNA repair genes. We evaluated potential gene-gene interactions and the association of multiple polymorphisms in a chromosome region using a multi-analytic strategy combining logistic regression, multi-factor dimensionality reduction and classification and regression tree approaches. We observed that, in combination, allelic variants in the XPC Ala499Val, NBN Glu185Gln, XRCC3 Thr241Me, XRCC1 Arg194Trp and XRCC1 399Gln polymorphisms modify the risk for developing HL. Moreover, the cumulative genetic risk score revealed a significant trend where the risk for developing HL increases as the number of adverse alleles in BER and DSB genes increase. These findings suggest that DNA repair variants in BER and DSB pathways may play an important role in the development of HL.
PMCID: PMC3131460  PMID: 21374732
21.  Folate Pathway Polymorphisms Predict Deficits in Attention and Processing Speed after Childhood Leukemia Therapy 
Pediatric blood & cancer  2011;57(3):454-460.
Neurocognitive impairment occurs in 20%-40% of childhood acute lymphoblastic leukemia (ALL) survivors, possibly mediated by folate depletion and homocysteine elevation following methotrexate treatment. We evaluated the relationship between folate pathway polymorphisms and neurocognitive impairment after childhood ALL chemotherapy.
Seventy-two childhood ALL survivors treated with chemotherapy alone underwent a neurocognitive battery consisting of: Trail Making Tests A (TMTA) and B (TMTB), Grooved Pegboard Test Dominant-Hand and Nondominant-Hand, Digit Span subtest, and Verbal Fluency Test. We performed genotyping for: 10-methylenetetrahydrofolate reductase (MTHFR 677C>T and MTHFR 1298A>C), serine hydroxymethyltransferase (SHMT 1420C>T), methionine synthase (MS 2756 A>G), methionine synthase reductase (MTRR 66A>G), and thymidylate synthase (TSER). Student's two sample t-test and analysis of covariance were used to compare test scores by genotype.
General impairment on the neurocognitive battery was related to MTHFR 1298A>C (p=0.03) and MS 2756A>G (p=0.05). Specifically, survivors with MTHFR 1298AC/CC genotypes scored, on average, 13 points lower on TMTB than those with MTHFR 1298AA genotype (p=0.001). The MS 2756AA genotype was associated with a 12.2 point lower mean TMTA score, compared to MS 2756 AG/GG genotypes (p=0.01). The TSER 2R/3R and 3R/3R genotypes were associated with an 11.4 point lower mean score on TMTB, compared to the TSER 2R/2R genotype (p=0.03). Survivors with >6 folate pathway risk alleles demonstrated a 9.5 point lower mean TMTA score (p=0.06) and 14.5 point lower TMTB score (p=0.002) than survivors with <6 risk alleles.
Folate pathway polymorphisms are associated with deficits in attention and processing speed after childhood ALL therapy.
PMCID: PMC3134130  PMID: 21618410
folate; leukemia; neurocognitive; survivor
22.  Gender differences in sociodemographic and behavioral influences of physical activity in Mexican-origin adolescents 
Understanding the factors that contribute to physical activity (PA) in Mexican-origin adolescents is essential to the design of effective efforts to enhance PA participation in this population.
Multivariable logistic regression was used to identify sociodemographic and behavioral correlates of self-reported PA in school and community settings in 1,154 Mexican-origin adolescents aged 12–17 years in Houston, TX.
The majority of adolescents were born in the US (74%), approximately half (51%) were overweight or obese, and nearly three-quarters (73%) watched more than 2 hours of weekday television. Similarities and differences by setting and gender were observed in the relationships between sociodemographic and behavioral characteristics and PA. In boys, parental education and attending physical education (PE) were positively associated with PA across multiple PA outcomes. Adolescent linguistic acculturation was inversely associated with participation in community sports, whereas parental linguistic acculturation was positively associated with PA at school. In girls, PA in school and community settings was inversely associated with TV viewing and positively associated with PE participation.
These findings highlight similarities and differences in correlates of PA among boys and girls, and point towards potential sources of opportunities as well as disparities for PA behaviors in Mexican-origin adolescents.
PMCID: PMC3250565  PMID: 21952224
Mexican American; acculturation; physical education
23.  Comparison of therapeutic dosimetric data from passively scattered proton and photon craniospinal irradiations for medulloblastoma 
For many decades, the standard of care radiotherapy regimen for medulloblastoma has been photon (megavoltage x-rays) craniospinal irradiation (CSI). The late effects associated with CSI are well-documented in the literature and are in-part attributed to unwanted dose to healthy tissue. Recently, there is growing interest in using proton therapy for CSI in pediatric and adolescent patients to reduce this undesirable dose. Previous comparisons of dose to target and non-target organs from conventional photon CSI and passively scattered proton CSI have been limited to small populations (n ≤ 3) and have not considered the use of age-dependent target volumes in proton CSI.
Standard of care treatment plans were developed for both photon and proton CSI for 18 patients. This cohort included both male and female medulloblastoma patients whose ages, heights, and weights spanned a clinically relevant and representative spectrum (age 2–16, BMI 16.4–37.9 kg/m2). Differences in plans were evaluated using Wilcoxon signed rank tests for various dosimetric parameters for the target volumes and normal tissue.
Proton CSI improved normal tissue sparing while also providing more homogeneous target coverage than photon CSI for patients across a wide age and BMI spectrum. Of the 24 parameters (V5, V10, V15, and V20 in the esophagus, heart, liver, thyroid, kidneys, and lungs) Wilcoxon signed rank test results indicated 20 were significantly higher for photon CSI compared to proton CSI (p ≤ 0.05) . Specifically, V15 and V20 in all six organs and V5, V10 in the esophagus, heart, liver, and thyroid were significantly higher with photon CSI.
Our patient cohort is the largest, to date, in which CSI with proton and photon therapies have been compared. This work adds to the body of literature that proton CSI reduces dose to normal tissue compared to photon CSI for pediatric patients who are at substantial risk for developing radiogenic late effects. Although the present study focused on medulloblastoma, our findings are generally applicable to other tumors that are treated with CSI.
PMCID: PMC3430590  PMID: 22828073
Proton; Photon; Craniospinal irradiation; CSI; Medulloblastoma
24.  Policy implications of early onset breast cancer among Mexican-origin women 
Cancer  2011;117(2):390-397.
Overall, Latinas are more likely to be diagnosed with a more advanced stage of breast cancer, and are 20% more likely to die of breast cancer than non-Hispanic white women. It is estimated that from 2003–2006, $82.0 billion in direct medical care expenditures, in addition to 100,000 lives annually, could be saved by eliminating health disparities experienced by Latinos and increasing the use of up to five preventive services in the U.S. An additional 3,700 lives could be saved if 90% of women ≥40 years were recently screened for breast cancer. We examined risk for breast cancer in a case-control population-based sample of Mexican-origin women in Harris County, TX (n=714), where rates of breast cancer mortality for Latina women have doubled since 1990. Half of breast cancer cases (n=119) were diagnosed before the age of 50. In a multivariable model, women with a family history of breast cancer (OR=4.3), born in Mexico and having high levels of language acculturation (OR=2.5), and without health insurance (OR=1.6) were found to have the highest risk of breast cancer. Because Mexican-origin women were found to be of high-risk for early onset pre-menopausal breast cancer, we recommend policies targeting screening, education and treatment to prevent increased disparities in mortality. The inclusion of community members and policymakers as partners in these endeavors would further safeguard against an increase in cancer health disparities, and aid in formulating a policy agenda congruent with scientifically-based, community-driven policy efforts addressing breast cancer screening, education and treatment in this vulnerable population.
PMCID: PMC3071526  PMID: 21319396
25.  The Advantage of Imputation of Missing Income Data to Evaluate the Association Between Income and Self-Reported Health Status (SRH) in a Mexican American Cohort Study 
Missing data often occur in cross-sectional surveys and longitudinal and experimental studies. The purpose of this study was to compare the prediction of self-rated health (SRH), a robust predictor of morbidity and mortality among diverse populations, before and after imputation of the missing variable “yearly household income.” We reviewed data from 4,162 participants of Mexican origin recruited from July 1, 2002, through December 31, 2005, and who were enrolled in a population-based cohort study. Missing yearly income data were imputed using three different single imputation methods and one multiple imputation under a Bayesian approach. Of 4,162 participants, 3,121 were randomly assigned to a training set (to derive the yearly income imputation methods and develop the health-outcome prediction models) and 1,041 to a testing set (to compare the areas under the curve (AUC) of the receiver-operating characteristic of the resulting health-outcome prediction models). The discriminatory powers of the SRH prediction models were good (range, 69–72%) and compared to the prediction model obtained after no imputation of missing yearly income, all other imputation methods improved the prediction of SRH (P<0.05 for all comparisons) with the AUC for the model after multiple imputation being the highest (AUC = 0.731). Furthermore, given that yearly income was imputed using multiple imputation, the odds of SRH as good or better increased by 11% for each $5,000 increment in yearly income. This study showed that although imputation of missing data for a key predictor variable can improve a risk health-outcome prediction model, further work is needed to illuminate the risk factors associated with SRH.
PMCID: PMC3205225  PMID: 21103931
Self-rated health; Missing income data; Data imputation techniques; Mean substitution; Multiple imputation; Minority health

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