Skip to main content
eScholarship
Open Access Publications from the University of California

Scholarly Works (10 results)

  • Thesis
  • Peer Reviewed
UCLA Electronic Theses and Dissertations (2017)

It is hypothesized that about half of all childhood cancers have prenatal origins. The first two studies of this dissertation focus on prenatal risk factors for childhood cancers. The first study includes cancer cases identified from the California Cancer Registry and diagnosed under six years of age between 1988 and 2013. Controls were selected from California birth records and matched to cases on birth year. Using birth certificate information, we assessed the association between pre-pregnancy diabetes, gestational diabetes, pre-pregnancy body mass index, gestational weight gain, and childhood cancer risk. We found an increased risk of acute lymphoblastic leukemia in offspring of mothers with pre-pregnancy diabetes.

Our second study includes the same sample of children, but limited to children of Hispanic mothers. Census tract data from the US decennial census (1990, 2000) and the American Community Survey (2007-2011) was used to create an index measure of Hispanic enclaves. Overall, offspring of mothers residing outside of Hispanic enclaves during pregnancy were at reduced risk of acute myeloid leukemia, hepatoblastoma, and retinoblastoma.

The effect of prenatal exposures can also be assessed using measures of placental vascular resistance, which have been shown to be predictive of adverse pregnancy outcomes. In the third study, we examined whether prenatal exposure to air pollution and smoking increases placental vascular resistance. Our sample includes pregnant women recruited between 1993 and 1996 in Los Angeles, California. We found that air pollution exposure increased uterine artery resistance in late pregnancy. Additionally, being a former smoker increases umbilical resistance in late pregnancy while smoking during pregnancy increases umbilical resistance, and uterine resistance and notching in mid-pregnancy.

In conclusion, our findings underline the importance of management of diabetes during pregnancy in childhood cancer prevention. Our results also suggest that Hispanic women living in densely populated Hispanic neighborhoods may be more vulnerable to certain risk factors as offspring of mothers living outside of these enclaves had a reduced risk of some cancers. Lastly, our results for prenatal air pollution and smoking support that both influence placental vascular resistance, providing insight on a potential mechanistic link between these exposures and adverse pregnancy outcomes.

    Cover page: Prenatal risk factors for childhood cancer and placental vascular resistance: an investigation of maternal metabolic factors and smoking, Hispanic enclaves, and air pollution
    • Article
    • Peer Reviewed
    Tobacco-Related Disease Research Program Funded Publications (2016)
      Cover page: Maternal pre-pregnancy and gestational diabetes, obesity, gestational weight gain, and risk of cancer in young children: a population-based study in California
      • Article
      • Peer Reviewed
      UCLA Previously Published Works (2019)

      Objectives

      Only a small number of studies have reported on the association of parental occupational exposure to benzene and risk of childhood and adolescent leukaemias. We examined associations with acute lymphoblastic leukaemia (ALL) in this population-based study in Denmark.

      Methods

      Benzene was largely banned from Danish workplaces after 1975, thus this case-control study focused on the immediately prior years. Paediatric cancer cases (ResultsWe identified 217 employed case fathers and 169 employed case mothers, of which 22 (10.1%) and 11 (6.5%), respectively, were exposed to benzene (vs 6.7% and 2.9% of control fathers and mothers). Most exposed parents worked as machine or engine mechanics, or in the shoe industry. Maternal occupational exposure to benzene in pregnancy was related to increased risk of ALL in offspring (adjusted OR=2.28, 95% CI 1.17 to 4.41), while paternal preconceptional benzene exposure was not as strongly associated (adjusted OR=1.40, 95% CI 0.88 to 2.22).

      Conclusions

      Our study supports an increased risk for ALL with parental occupational benzene exposure.
        Cover page: Parental occupational exposure to benzene and the risk of childhood and adolescent acute lymphoblastic leukaemia: a population-based study
        • Article
        • Peer Reviewed
        UCLA Previously Published Works (2016)
        Smoking during pregnancy is a plausible risk factor for childhood cancer, yet previous studies have yielded conflicting results, and few prospective studies have been published. Data on maternal smoking were obtained from California birth certificates. We linked California birth certificates (births 2007-2011) with California Cancer Registry records for childhood cancer cases (diagnosed January 2007-September 2013) that were ages 5 or younger at diagnosis (N cases = 2,021). Controls (N = 40,356) were frequency-matched by birth year and randomly selected from birth certificate records. We used unconditional logistic regression to obtain odds ratios (OR) and 95% confidence intervals (CI) to assess the association between smoking during pregnancy and childhood cancer. We observed positive associations for gliomas (OR = 1.8, 95% CI: 1.0-3.4) and retinoblastoma (OR = 3.0, 95% CI: 1.4-6.6), particularly bilateral retinoblastoma (OR = 9.4, 95% CI 3.6-24.7) with maternal smoking in pregnancy. Maternal smoking during pregnancy may be a risk factor for retinoblastoma and certain types of childhood brain tumors.
          • Article
          • Peer Reviewed
          Tobacco-Related Disease Research Program Funded Publications (2016)

          Smoking during pregnancy is a plausible risk factor for childhood cancer, yet previous studies have yielded conflicting results, and few prospective studies have been published. Data on maternal smoking were obtained from California birth certificates. We linked California birth certificates (births 2007-2011) with California Cancer Registry records for childhood cancer cases (diagnosed January 2007- September 2013) that were ages 5 or younger at diagnosis (N cases=2,021). Controls (N=40,356) were frequency-matched by birth year and randomly selected from birth certificate records. We used unconditional logistic regression to obtain odds ratios (OR) and 95% confidence intervals (CI) to assess the association between smoking during pregnancy and childhood cancer. We observed positive associations for gliomas (OR=1.8, 95% CI: 1.0-3.4) and retinoblastoma (OR=3.0, 95% CI: 1.4-6.6), particularly bilateral retinoblastoma (OR=9.4, 95% CI 3.6-24.7) with maternal smoking in pregnancy. Maternal smoking during pregnancy may be a risk factor for retinoblastoma and certain types of childhood brain tumors. This article is protected by copyright. All rights reserved.

            Cover page: Smoking in pregnancy and risk of cancer among young children: A population-based study.
            • Article
            • Peer Reviewed
            Tobacco-Related Disease Research Program Funded Publications (2017)
            Background

            Though the association between parental age at child’s birth and the risk of childhood cancer has been previously investigated, the evidence to date is inconclusive and scarce for rarer cancer types.

            Methods

            Cancer cases (N=5,856) were selected from all children born from 1968–2014 and diagnosed from 1968–2015 in Denmark at less than 16 years of age listed in the nationwide Danish Cancer Registry. Cases were individually matched to controls (1:100) on sex and year of birth with a total of 585,594 controls randomly sampled from all live births in Denmark from the Danish Central Population Registry. Parental age at child’s birth was extracted from the Central Population Registry. Conditional logistic regression models were used to estimate odds ratios for the association between parental age at child’s birth and childhood cancer risk. Parental age was modeled as both categorical (referent group, parents aged 25–29) and continuous per 5-year increase in age.

            Results

            Offspring of older mothers were at an increased risk of acute lymphoblastic leukemia (ALL) [OR=1.10, 95% CI: (1.02, 1.19) per 5-year increase in age]. Older maternal age (40+) increased the risk of non-Hodgkin lymphoma (NHL) [OR=1.96, 95%CI: (1.12, 3.43)]. The risk of Wilms’ tumor also appeared elevated with older paternal age [OR=1.11, 95% CI: (0.97, 1.28) per 5-year increment in age].

            Conclusion

            Older parental age was a risk factor for various childhood cancers in Danish children. Further investigation of the biological and social factors that may be contributing to these associations is warranted.

              Cover page: Parental age and childhood cancer risk: A Danish population-based registry study
              • Article
              • Peer Reviewed
              UCLA Previously Published Works (2017)

              Background

              Though the association between parental age at child's birth and the risk of childhood cancer has been previously investigated, the evidence to date is inconclusive and scarce for rarer cancer types.

              Methods

              Cancer cases (N=5,856) were selected from all children born from 1968 to 2014 and diagnosed from 1968 to 2015 in Denmark at less than 16 years of age listed in the nationwide Danish Cancer Registry. Cases were individually matched to controls (1:100) on sex and year of birth with a total of 585,594 controls randomly sampled from all live births in Denmark from the Danish Central Population Registry. Parental age at child's birth was extracted from the Central Population Registry. Conditional logistic regression models were used to estimate odds ratios for the association between parental age at child's birth and childhood cancer risk. Parental age was modeled as both categorical (referent group, parents aged 25-29) and continuous per 5-year increase in age.

              Results

              Offspring of older mothers were at an increased risk of acute lymphoblastic leukemia [OR=1.10, 95% CI: (1.02, 1.19) per 5-year increase in age]. Older maternal age (40+) increased the risk of non-Hodgkin lymphoma [OR=1.96, 95%CI: (1.12, 3.43)]. The risk of Wilms' tumor also appeared elevated with older paternal age [OR=1.11, 95% CI: (0.97, 1.28) per 5-year increment in age].

              Conclusion

              Older parental age was a risk factor for various childhood cancers in Danish children. Further investigation of the biological and social factors that may be contributing to these associations is warranted.
                • Article
                • Peer Reviewed
                UCLA Previously Published Works (2016)

                Importance

                The Hispanic epidemiologic paradox is the phenomenon that non-US-born Hispanic mothers who immigrate to the United States have better pregnancy outcomes than their US-born counterparts. It is unknown whether this advantage extends to childhood cancer risk.

                Objective

                To determine whether the risk for childhood cancers among Hispanic children varies by maternal birthplace.

                Design, setting, and participants

                In this population-based case-control study conducted in June 2015, cohort members were identified through California birth records of children born in California from January 1, 1983, to December 31, 2011. Information on cancer diagnoses was obtained from California Cancer Registry records from 1988 to 2012. Cases (n = 13 666) were identified from among children younger than 6 years in the California Cancer Registry and matched to California birth certificates. Control children (n = 15 513 718) included all other children born in California during the same period. Maternal birthplace and ethnic ancestry were identified from the birth certificate.

                Main exposures

                Maternal race/ethnicity and birthplace.

                Main outcomes and measures

                We used Cox proportional hazards modeling to estimate hazard ratios (HRs) of childhood cancer.

                Results

                Included in the study were 4 246 295 children of non-Hispanic white mothers (51.3% male), 2 548 822 children of US-born Hispanic mothers (51.0% male), and 4 397 703 children of non-US-born Hispanic mothers (51.0% male). Compared with children of non-Hispanic white mothers, the children of non-US-born Hispanic mothers had a reduced risk for glioma (HR, 0.50; 95% CI, 0.44-0.58), astrocytoma (HR, 0.43; 95% CI, 0.36-0.51), neuroblastoma (HR, 0.47; 95% CI, 0.40-0.54), and Wilms tumor (HR, 0.70; 95% CI, 0.59-0.82). For these cancer types, the risk estimates for children of US-born Hispanic mothers fell between those of the children of US-born white and non-US-born Hispanic mothers. Children of Mexican-born mothers had a higher risk of yolk sac tumors (HR, 1.46; 95% CI, 0.99-2.17), while children of US-born Hispanic mothers with ancestry from countries other than Mexico had a higher risk for unilateral retinoblastoma (HR, 2.03; 95% CI, 1.33-3.11).

                Conclusions and relevance

                For several cancers, we observed differential risk by maternal place of birth. Examining the differences in health behaviors and environment between Hispanic groups may shed light on childhood cancer etiology.
                  • Article
                  • Peer Reviewed
                  UCLA Previously Published Works (2018)

                  Background

                  Prenatal exposure to air pollution and smoking increases the risk of pregnancy complications and adverse birth outcomes, but pathophysiologic mechanisms are still debated. Few studies to date have examined the influence of air pollution on uterine vascular resistance and no studies have examined the independent impact of these exposures. We aimed to assess the impact of prenatal exposure to traffic-related air pollution and smoking on uterine vascular resistance.

                  Methods

                  Our study included 566 pregnant women recruited between 1993 and 1996 in Los Angeles who completed visits at three gestational ages. Information on smoking was collected and uterine vascular resistance was measured at each visit by Doppler ultrasound. We calculated three resistance indices: the resistance index (RI), the pulsatility index (PI), and the systolic/diastolic (S/D) ratio. We estimated exposure to NO2 at the home address of the mother using a land use regression (LUR) model and to NOx using CALINE4 air dispersion modeling. We used generalized linear mixed models to estimate the effects of air pollution and smoking on uterine vascular resistance indices.

                  Results

                  LUR-derived NO2 and CALINE4-derived NOx exposure increased the risk of high uterine artery resistance in late pregnancy. Smoking during pregnancy also increased the risk of higher uterine resistance and contributed to bilateral notching in mid-pregnancy.

                  Conclusion

                  Our results suggest that uterine vascular resistance is a mechanism underlying the association between smoking and air pollution, and adverse birth outcomes.
                    Cover page: Prenatal air pollution exposure, smoking, and uterine vascular resistance
                    • Article
                    • Peer Reviewed
                    UCLA Previously Published Works (2019)
                    The aim of this study was to examine various psychosocial, behavioral, and socio-environmental factors in a multiethnic sample of healthy-weight, overweight, and obese youths in the United States (US) and Mexico and determine differences by sex. We conducted a cross-sectional analysis of 633 youths aged 11-18 years who completed a self-reported questionnaire. Height and weight were measured to determine body mass index (BMI). Overweight and obese youth in both countries were significantly more likely to report a higher body image dissatisfaction (Odds Ratio (OR) = 1.67 and OR= 2.95, respectively), depressive symptoms (OR = 1.08 and OR = 1.12, respectively), perceive themselves as overweight (OR = 2.57) or obese (OR = 5.30), and a lower weight-specific quality of life (OR = 0.97 and OR = 0.95, respectively) than healthy-weight youth. Obese youth have lower healthy lifestyle priorities (OR = 0.75) and are less likely to be physically active (OR = 0.79) and eat breakfast (OR = 0.47) than healthy-weight youth. Additionally, overweight and obese youth are more likely to engage in weight control behaviors (OR = 5.19 and OR = 8.88, respectively) and restrained eating than healthy-weight youth. All the aforementioned results had a p-value of <0.05, which was considered statistically significant. The association between these factors and overweight or obesity remained significant after controlling for age, sex, race/ethnicity, and country. In conclusion, obesity was associated with a range of psychosocial, behavioral, and socio-environmental risk factors in both countries. Our findings support the need for multifactorial approaches when developing interventions to address the growing problem of obesity among youth in the US and Mexico.
                      Cover page: Increased Prevalence of Psychosocial, Behavioral, and Socio-Environmental Risk Factors among Overweight and Obese Youths in Mexico and the United States
                      Top