Effect of maternal weight status on the relationship between prenatal smoking and infant birth weight

The purpose of this study was to assess the effect of maternal pre-pregnancy weight status on the relationship between prenatal smoking and infant birth weight (IBW). Prenatal cigarette smoking and maternal weight exert opposing effects on IBW; smoking decreases birth weight while maternal pre-pregnancy weight is positively correlated with birth weight. As such, mutual effect modification may be sufficiently significant to alter the independent effects of these two birth weight correlates. Finding of such an effect has implications of prenatal smoking cessation education. Perception of risk is an important determinant of smoking cessation, and reduced or low birth weight (LBW) as a smoking-associated risk predominates prenatal smoking counseling and education. In a population such as the US, where obesity is becoming epidemic, particularly among minority and low-income groups, perception of risk may be lowered should increased maternal size attenuate the effect of smoking. Previous studies have not found a significant interaction effect of prenatal smoking and maternal pre-pregnancy weight on IBW; however, use of self-reported smoking status may have biased findings. Reliability of self-reported smoking status reported in the literature is variable, with deception rates ranging from a low of 5% to as high as 16%. This study, using data from a prenatal smoking cessation project, in which smoking status was validated by saliva cotinine, was an opportunity to assess effect modification of smoking and maternal weight using biochemically determined smoking status in lieu of self report. Stratified by saliva cotinine, 151 women from a prenatal smoking cessation cohort, who were 18 years and older and had full-term, singleton births, were included in this study. The effect of smoking in terms of mean birth weight across three levels of maternal pre-pregnancy weight was assessed by general linear modeling procedures, adjusting for other known correlates of IBW. Effect modification was marginally significant, p = .104, but only with control for differential effects among racial/ethnic groups. A smaller than planned sample of nonsmokers, or women who quit smoking during the pregnancy, prohibited rejection of the null hypothesis of no difference in the effect of smoking across levels of pre-pregnancy weight. ^

Behavioral decision making and the levels of change: An application of the transtheoretical model to prenatal smoking in low -income women

Despite continued research and public health efforts to reduce smoking during pregnancy, prenatal cessation rates in the United States have decreased and the incidence of low birth weight has increased from 1985 to 1991. Lower socioeconomic status women who are at increased risk for poor pregnancy outcomes may be resistant to current intervention efforts during pregnancy. The purpose of this dissertation was to investigate the determinants of continued smoking and quitting among low-income pregnant women.^ Using data from cross-sectional surveys of 323 low-income pregnant smokers, the first study developed and tested measures of the pros and cons of smoking during pregnancy. The original decisional balance measure for smoking was compared with a new measure that added items thought to be more salient to the target population. Confirmatory factor analysis using structural equation modeling showed neither the original nor new measure fit the data adequately. Using behavioral science theory, content from interviews with the population, and statistical evidence, two 7-item scales representing the pros and cons were developed from a portion (n = 215) of the sample and successfully cross-validated on the remainder of the sample (n = 108). Logistic regression found only pros were significantly associated with continued smoking. In a discriminant function analysis, stage of change was significantly associated with pros and cons of smoking.^ The second study examined the structural relationships between psychosocial constructs representing some of the levels of and the pros and cons of smoking. The cross-sectional design mandates that statements made regarding prediction do not prove causation or directionality from the data or methods analysis. Structural equation modeling found the following: more stressors and family criticism were significantly more predictive of negative affect than social support; a bi-directional relationship was found between negative affect and current nicotine addiction; and negative affect, addiction, stressors, and family criticism were significant predictors of pros of smoking.^ The findings imply reversing the trend of decreasing smoking cessation during pregnancy may require supplementing current interventions for this population of pregnant smokers with programs addressing nicotine addiction, negative affect, and other psychosocial factors such as family functioning and stressors. ^

Attention-Deficit/Hyperactivity Disorder and antidepressants and prescription medications: A pilot study

Background. Attention Deficit-Hyperactivity Disorder (AD/HD) diagnosis in children and adolescents has been on the rise over the last couple of decades and a multitude of studies have been conducted in an aim to better understand the disease. Literature has explored the role of several factors suspected of contributing to development of the disease, including: prenatal smoking exposures, environmental exposures, and low-birth weight. However, there is very limited reporting of fetal/infant exposure to antidepressants and prescription medications and the long-term behavioral outcomes, namely development of AD/HD. The purpose of this study was to evaluate the relationship between mother's exposure to prescription medications and/or antidepressants around the time of conception, during pregnancy, or while breastfeeding and the development of Attention-Deficit/Hyperactivity Disorder in offspring. Methods. Secondary analysis of data from a case-control study was performed. Exposure histories were collected for the mother and offspring. Data were collected using a secure, confidential, self-report, online survey to evaluate the relationship between antidepressant and/or prescription medication exposure and the development of AD/HD. The period of exposure to these drugs was defined as: around the time of conception, during pregnancy, or while breastfeeding. Cases were defined as a child who had been diagnosed with AD/HD. Controls were defined as a child who had not been diagnosed with AD/HD. Results. Prescription medication and antidepressant medication exposures around the time of conception, during pregnancy, or while breastfeeding were not associated with development of AD/HD. However, traumatic brain injury (OR=2.77 (1.61–4.77)) and preterm birth (OR=1.48 (1.04–2.12)) were identified as potential risk factors. These results support existing literature on AD/HD, but future work must be undertaken to better evaluate fetal/infant medication exposures and long-term behavioral outcomes.^

Ultrasound feedback and motivational interviewing targeting smoking cessation in the second and third trimesters of pregnancy.

INTRODUCTION: Cigarette smoking during pregnancy is associated with poor maternal and child health outcomes. Effective interventions to increase smoking cessation rates are needed particularly for pregnant women unable to quit in their first trimester. Real-time ultrasound feedback focused on potential effects of smoking on the fetus may be an effective treatment adjunct, improving smoking outcomes. METHODS: A prospective randomized trial was conducted to evaluate the efficacy of a smoking cessation intervention consisting of personalized feedback during ultrasound plus motivational interviewing-based counseling sessions. Pregnant smokers (N = 360) between 16 and 26 weeks of gestation were randomly assigned to one of three groups: Best Practice (BP) only, Best Practice plus ultrasound feedback (BP+US), or Motivational Interviewing-based counseling plus ultrasound feedback (MI+US). Assessments were conducted at baseline and end of pregnancy (EOP). RESULTS: Analyses of cotinine-verified self-reported smoking status at EOP indicated that 10.8% of the BP group was not smoking at EOP; 14.2% in the BP+US condition and 18.3% who received MI+US were abstinent, but differences were not statistically significant. Intervention effects were found conditional upon level of baseline smoking, however. Nearly 34% of light smokers (< or =10 cigarettes/day) in the MI+US condition were abstinent at EOP, followed by 25.8% and 15.6% in the BP+US and BP conditions, respectively. Heavy smokers (>10 cigarettes/day) were notably unaffected by the intervention. DISCUSSION: Future research should confirm benefit of motivational interviewing plus ultrasound feedback for pregnant light smokers and explore mechanisms of action. Innovative interventions for pregnant women smoking at high levels are sorely needed.

Content of prenatal care and spontaneous preterm birth: Findings from the 1988 National Maternal and Infant Health Survey

The purposes of this study were to examine (1) the relationship between selected components of the content of prenatal care and spontaneous preterm birth; and (2) the degree of comparability between maternal and caregivers' responses regarding the number of prenatal care visits, selected components of the content of prenatal care, and gestational age, based on analyses of the 1988 National Maternal and Infant Health Survey conducted by the National Centers for Health Statistics. Spontaneous preterm birth was subcategorized into very preterm and moderately preterm births, with term birth as the controls. The study population was limited to non-Hispanic Anglo- and African-American mothers. The racial differences in terms of birth outcomes were also compared.^ This study concluded that: (1) there was not a high degree of comparability (less than 80%) between maternal and prenatal care provider's responses regarding the number of prenatal care visits and the content of prenatal care; (2) there was a low degree of comparability (less than 50%) between maternal and infant's hospital of delivery responses regarding gestational age at birth; (3) there were differences in selected components of the content of prenatal care between the cases and controls, overall and stratified by ethnicity (i.e., hemoglobin/hematocrit test, weight measurement, and breast-feeding counseling), but they were confounded with missing values and associated preterm delivery bias; (4) there were differences in selected components of the content of prenatal care between Anglo- and African-American cases (i.e., vitamin/mineral supplement advice, weight measurement, smoking cessation and drug abuse counseling), but they, too, were difficult to interpret definitively due to item nonresponse and preterm delivery biases; (5) no significant predictive association between selected components of the content of prenatal care and spontaneous preterm birth was found; and (6) inadequate/intermediate prenatal care and birth out of wedlock were found to be associated with moderately preterm birth.^ Future research is needed to examine the validity of maternal and prenatal care providers' responses and identify the sources of disagreement between their responses. In addition, further studies are needed to examine the relationship between the quality of prenatal care and preterm birth. Finally, the completeness and quality of patient and provider data on the utilization and content of prenatal care needs to be strengthened in subsequent studies. ^

Factors affecting prenatal care use and pregnancy outcome in Texas: A comparative study among and within Black, Anglo, and Hispanic populations

This research project is a study in the field of public health to test the relationships of demographic, socioeconomic, behavioral, and biological factors with (1) prenatal care use and (2) pregnancy outcome, measured by birth weight. It has been postulated that demographic, socioeconomic, and behavioral factors are associated with differences in the use of prenatal care services. It has also been postulated that differences in demographic, socioeconomic, behavioral, and biological factors result in differences in birth weight. This research attempts to test these two basic conceptual frameworks. At the same time, an attempt is made to determine the population groups and subgroups that are at increased risk (1) of using fewer prenatal care visits, and (2) of displaying a higher incidence of low birth weight babies. An understanding of these relationships of the demographic, socioeconomic, behavioral, and biological factors in the use of prenatal care visits and pregnancy outcome, measured by birth weight, will potentially offer guidance in the planning and policy development of maternal and child health services. The research considers four major components of maternal characteristics: (1) Demographic factors. Ethnicity, household size, maternal parity, and maternal age; (2) Socioeconomic factors. Maternal education, family income, maternal employment, health insurance coverage, and household dwelling; (3) Behavioral factors. Maternal smoking, attendance at child development classes, mother's first prenatal care visit, total number of prenatal care visits, and adequacy of care; and, (4) Biological factors. Maternal weight gain during pregnancy.^ The research considers 16 independent variables and two dependent variables.^ It was concluded that: (1) Generally, differences in demographic, socioeconomic, and behavioral factors were associated with differences in the average number of prenatal care visits between and within population groups and subgroups. The Hispanic mothers were the lowest users of prenatal care services. (2) In some cases, differences in demographic, socioeconomic, behavioral, and biological factors demonstrated differences in the average birth weight of infants between and within population groups and subgroups. (3) Differences in demographic, socioeconomic, behavioral, and biological factors resulted in differences in the rates of low birth weight babies between and within population groups and subgroups. The Black mothers delivered the highest incidence of low birth weight infants.^ These findings could provide guidance in the formulation of public health policies such as MCH services, an increase in the use of prenatal care services by prospective mothers, resulting in reduction of the incidence of low birth weight babies, and consequently aid in reducing the rates of infant mortality. ^

The effects of adequacy and content of prenatal care on birth outcomes in a high -risk Missouri population

The purpose of this observational study was investigation of the relationship between quantitative adequacy of prenatal care, specific prenatal care content and pregnancy outcome in a high risk Missouri population. A sample of 1484 women from three Missouri regions known to have high rates of low birth weight, infant mortality, and inadequate prenatal care rates participated in structured post-partum interviews. Approximately one-half of the sample had received adequate prenatal care and the other half inadequate prenatal care as determined by an index utilized by the Missouri Department of Health.^ Prenatal care content was assessed by reports of prenatal education in six different areas: Diet, smoking, alcohol, drug, preterm labor counseling, and advice on when to call the health provider if preterm labor was suspected by the woman. Low birth weight, in both term and preterm infants, were the two birth outcomes examined. A variety of maternal socio-demographic variables were also considered.^ The results of this study suggest that specific educational content, delivered during prenatal care, may have lessen the risk of giving birth to a preterm-low birth weight infant. Prenatal education for recognition of preterm labor, and advice on when to call the health provider if preterm labor was suspected were found to be associated with a decreased risk of preterm delivery. Specific educational content was not, however, associated with risk of term-low weight birth nor was quantitative adequacy of care associated with the risk of either term- or preterm-low birth weight.^ These findings reinforce a body of literature which stresses the importance of appropriate prenatal care in preventing preterm low birth weight. Additionally, the findings suggest interventions that may be specifically effective for prematurity prevention. ^

Does cigarette smoking modify the association between change in body mass index during young adulthood and risk of coronary mortality during middle-age in men? Twenty-five year follow-up results from the Chicago Western Electric Study

Many persons in the U.S. gain weight during young adulthood, and the prevalence of obesity has been increasing among young adults. Although obesity and physical inactivity are generally recognized as risk factors for coronary heart disease (CHD), the magnitude of their effect on risk may have been seriously underestimated due to failure to adequately handle the problem of cigarette smoking. Since cigarette smoking causes weight loss, physically inactive cigarette smokers may remain relatively lean because they smoke cigarettes. We hypothesize cigarette smoking modifies the association between weight gain during young adulthood and risk of coronary heart disease during middle age, and that the true effect of weight gain during young adulthood on risk of CHD can be assessed only in persons who have not smoked cigarettes. Specifically, we hypothesize that weight gain during young adulthood is positively associated with risk of CHD during middle-age in nonsmokers but that the association is much smaller or absent entirely among cigarette smokers. The purpose of this study was to test this hypothesis. The population for analysis was comprised of 1,934 middle-aged, employed men whose average age at the baseline examination was 48.7 years. Information collected at the baseline examinations in 1958 and 1959 included recalled weight at age 20, present weight, height, smoking status, and other CHD risk factors. To decrease the effect of intraindividual variation, the mean values of the 1958 and 1959 baseline examinations were used in analyses. Change in body mass index ($\Delta$BMI) during young adulthood was the primary exposure variable and was measured as BMI at baseline (kg/m$\sp2)$ minus BMI at age 20 (kg/m$\sp2).$ Proportional hazards regression analysis was used to generate relative risks of CHD mortality by category of $\Delta$BMI and cigarette smoking status after adjustment for age, family history of CVD, major organ system disease, BMI at age 20, and number of cigarettes smoked per day. Adjustment was not performed for systolic blood pressure or total serum cholesterol as these were regarded as intervening variables. Vital status was known for all men on the 25th anniversary of their baseline examinations. 705 deaths (including 319 CHD deaths) occurred over 40,136 person-years of experience. $\Delta$BMI was positively associated with risk of CHD mortality in never-smokers, but not in ever-smokers (p for interaction = 0.067). For never-smokers with $\Delta$BMI of stable, low gain, moderate gain, and high gain, adjusted relative risks were 1.00, 1.62, 1.61, and 2.78, respectively (p for trend = 0.010). For ever-smokers, with $\Delta$BMI of stable, low gain, moderate gain, and high gain, adjusted relative risks were 1.00, 0.74, 1.07, and 1.06, respectively (p for trend = 0.422). These results support the research hypothesis that cigarette smoking modifies the association between weight gain and CHD mortality. Current estimates of the magnitude of effect of obesity and physical inactivity on risk of coronary mortality may have been seriously underestimated due to inadequate handling of cigarette smoking. ^

Cigarette smoking and Ecuadorian adolescents: A cross-sectional survey and policy review

This study investigates the relationship between cigarette smoking and adolescents in Ecuador, South America. Using the Social Learning Theory as a basis, the cross-sectional survey focuses attention on such social influences as the smoking habits of family members and peers as well as, the role of cigarette advertisements. Actual use prevalence, access to cigarettes and knowledge and attitudes about smoking are also obtained.^ The survey was conducted in both urban and rural areas, with 50 schools in 40 different communities participating. Two thousand four hundred and fifty-seven adolescents aged 9 to 15 years completed a self-administered questionnaire. This part of the study was conducted in collaboration with the international health organization Amigos de las Americas (AMIGOS). Staff assigned to the AMIGOS Ecuador projects worked with local health and education officials to implement the cross-sectional survey in the field.^ The key informant survey and subsequent policy review were designed to illuminate the social, cultural and institutional environment for anti-smoking activities and interventions in Ecuador. Key individuals involved with this issue on both national and local levels were interviewed. A review of past legislative efforts and present anti-smoking laws was also conducted.^ The current smoking prevalence among the study population was 8.6 percent. Findings from the cross-sectional survey revealed significant positive associations between the smoking habits of siblings and peers and the smoking behavior of the adolescents surveyed. Significant age and gender differences were also found in association with several different variables.^ The policy review found an unfavorable environment for anti-smoking efforts. Several factors contribute to this including, most importantly, lack of funding and lack of public support. The present anti-smoking law is often vague and lacks important provisions, such as a prohibition on selling tobacco products to minors.^ Together, the two surveys provide comprehensive information for the purpose of designing smoking prevention interventions. Using the results from the two surveys, recommendations for intervention are proposed. ^

A study of the impact of cigarette advertising on adolescent susceptibility to smoking among 5th-, 8th-, and 12th-grade students in Hempstead and Hitchcock Independent School Districts

This study assessed the impact of cigarette advertising on adolescent susceptibility to smoking in the Hempstead and Hitchcock Independent School Districts. A convenience sample of 217 youths, 10-19 years of age was recruited in the study. Students completed both a paper-and-pencil and a computer-aided questionnaire in April 1996. Adolescents were defined as susceptible to smoking if they could not definitely rule out the possibility of future smoking. For the analysis, an index was devised: a 5-point index of an individual's receptivity to cigarette advertising. The index is determined by the number of positive responses to five survey items (recognizing cigarette brand logos, recognizing cigarette advertisement's pictures, recognizing cigarette brand slogans, evaluating adolescent attitudes toward cigarette advertising, and the degree to which adolescents were exposed to cigarette advertisements). Using logistic regression, we assessed the independent importance of the index in predicting susceptibility to smoking and ever smoking after adjusting for sociodemographic variables, perceived school performance and family composition. Of students surveyed, 54.4% of students appeared to have started the smoking uptake process as measured by susceptibility to smoking. Camel was recognized by the majority of students (88%), followed by Marlboro (41.5%) and Newport (40.1%). The pattern for recognition of the cigarette advertisements was the same as the pattern of market for cigarette. Advertisement featuring the cartoon character Joe Camel was significantly more appealing to adolescents than were advertisements with human models, with animal models, and with text only (p $<$ 0.001). Text only advertisement was significantly less appealing than other types of advertisements. The cigarette advertisement with White models (Marlboro) had significantly higher appeal to White students than to African-American students (p $<$ 0.001). The cigarette advertisement featuring African-American models (Virginia Slims) was significantly more appealing to African-American students than other ethnic groups (p $<$ 0.001). Receptivity to cigarette advertising was to be an important concurrent predictor of past smoking experience and intention to smoke in the future. Adolescents who scored in the fourth quartile of the Index of Receptivity to Cigarette Advertising were 7.54 (95% confidence interval (CI) = 1.92-29.56) times as likely to be susceptible to smoking, and were 4.56 (95% CI = 1.55-13.38) times as likely to have tried smoking, as those who scored in the first quartile of the Index. The findings confirmed the hypothesis that cigarette advertising may be a strong current influence in encouraging adolescents to initiate the smoking uptake process than sociodemographic variables, perceived school performance and family composition. ^

The relationship of maternal low birthweight and infant low birthweight among African-American women at term delivery: Findings from the 1988 National Maternal and Infant Health Survey

A cohort study study design was used to study the relationship of maternal low birthweight and infant low birthweight among African American women delivering full term infants. The cohort consisted of 3,157 mother-infant pairs drawn from the 1988 National Maternal and Infant Health Survey conducted by the National Center for Health Statistics. The objectives of the study were (1) to determine if low birthweight, African American mothers delivering term infants experienced higher rates of infant low birthweight and (2) to examine the role of selected contributory variables in the relationship of maternal low birthweight and infant low birthweight. Contributory risk factors examined included maternal marital status, maternal age, maternal education, maternal height, maternal prepregnant weight, birth order, history of a prior low birthweight delivery, timing of prenatal care, number of prenatal visits, gestational length, infant gender, and behavioral factors of smoking, alcohol, and illicit drug use during pregnancy.^ Using logistic regression analysis, risk of infant low birthweight among maternal low birthweight mothers increased after controlling for less than a high school education, less than 20 years of age, prepregnant weight less than 100 lbs, history of a prior low birthweight delivery, birth order, smoking during pregnancy, and use of alcohol and illicit drugs during pregnancy, but was not statistically significant. Loss of statistical significance was attributed to a large reduction in cases available for analysis after including illicit drug use in the model.^ This study demonstrated a consistent pattern of increased rates of infant low birthweight among low birthweight mothers. The force of history remains, hence women with this trait should be carefully monitored and advised during pregnancy to decrease risk of a low birthweight infant, in order to decrease the chain of events leading to future generations of low birthweight mothers. ^

Hormonal risk factors and testicular cancer

The cause of testicular cancer is not known and recent hypotheses have suggested an altered hormonal milieu may increase the risk of testis cancer. This study examined modulation of testicular cancer risk by hormonal factors, specifically: environmental xenoestrogens (e.g. organochlorines), prenatal maternal estrogens, testosterone indices (age at puberty, severe adolescent acne, self-reported balding), sedentary lifestyle and dietary consumption of fats and phytoestrogens.^ A hospital based friend matched case-control study was conducted at the University of Texas M. D. Anderson Cancer Center in Houston, Texas, between January 1990 and October 1996. Cases had a first primary testis tumor diagnosed between age 18 to 50 years and resided in Texas, Louisiana, Oklahoma or Arkansas.^ Cases and friend controls completed a mail questionnaire and case/control mothers were contacted by phone regarding pregnancy related variables. The study population comprised 187 cases, 148 controls, 147 case mothers and 86 control mothers. Odds ratios were virtually identical whether the match was retained or dissolved, thus the analyses were conducted using unconditional logistic regression.^ Cryptorchidism was a strong risk factor for testis cancer with an age-adjusted odds ratio (OR) of 7.7 (95% confidence interval (CI): 2.3-26.3). In a final model (adjusted for age, education, and cryptorchidism), history of severe adolescent acne and self-reported balding were both significantly protective, as hypothesized. For acne (yes vs. no) the OR was 0.5 (CI: 0.3-1.0) and for balding (yes vs. no) the OR was 0.6 (CI: 0.3-1.0). Marijuana smoking was a risk factor among heavy, regular users (17 times/week, OR = 2.4; CI: 0.9-6.4) and higher saturated fat intake increased testis cancer risk (saturated fat intake $>$ 15.2 grams/day vs. $<$ 11.8 grams/day, OR = 3.3; CI: 1.5-7.1). Early puberty, xenoestrogen exposure, elevated maternal estrogen levels, sedentary lifestyle and dietary phytoestrogen intake were not associated with risk of testicular cancer.^ In conclusion, testicular cancer may be associated with endogenous androgen metabolism although environmental estrogen exposure can not be ruled out. Further research is needed to understand the underlying hormonal mechanisms and possible dietary influences. ^

Prenatal care: A survey of African American women in Houston

The focus of the study was to identify variables that African American women who delivered at a teaching hospital in Houston, Harris County, Texas, between January 12, 1998 and April 24, 1998 perceived to prevent them from receiving adequate prenatal care. The research was based on Aday and Andersen's Framework for the Study of Access to Medical Care. A self-administered questionnaire, using realized and potential access indicators, was developed and administered to 161 African American patients at the study hospital. ^ The objectives of the study were (1) to describe the demographic characteristics of African American women who delivered at a large urban teaching hospital between January 12, 1998 and April 24, 1998; and to determine the relationships between (2) predisposing factors such as age, race, educational level, marital status, family structure, social support and attitude toward prenatal care and prenatal care utilization; (3) enabling factors such as income, employment, insurance status, transportation, appointment, and regular source of care; (4) need factors such as perceived health status, number of past pregnancies, pregnancy occurrence; and (5) the relative importance of predisposing, enabling and need factors as predictors of utilization of prenatal care. The indicators of prenatal care utilization examined included the trimester in which the women initiated prenatal care, number of visits, and numbers and types of services received during pregnancy. Barriers cited included low income and inadequate insurance coverage, problems of transportation and child care, unawareness of pregnancy, delays in the scheduling of appointments, and having too many other problems. ^ The results of the study have implications for well-defined public health promotion campaigns, social support system enhancement, and appointment scheduling reform with an emphasis on prenatal care. ^

Primary lung cancer after breast cancer: The role of radiation therapy and cigarette smoking

The magnitude of the interaction between cigarette smoking, radiation therapy, and primary lung cancer after breast cancer remains unresolved. This case control study further examines the main and joint effects of cigarette smoking and radiation therapy (XRT) among breast cancer patients who subsequently developed primary lung cancer, at The University of Texas M. D. Anderson Cancer Center (MDACC) in Houston, Texas. Cases (n = 280) were women diagnosed with primary lung cancer between 1955 and 1970, between 30–89 years of age, who had a prior history of breast cancer, and were U.S. residents. Controls (n = 300) were randomly selected from 37,000 breast cancer patients at MDACC and frequency matched to cases on age at diagnosis (in 5-year strata), ethnicity, year of breast cancer diagnosis (in 5-year strata), and had survived at least as long as the time interval for lung cancer diagnosis in the cases. Stratified analysis and unconditional logistic regression modeling were used to calculate the main and joint effects of cigarette smoking and radiation treatment on lung cancer risk. Medical record review yielded smoking information on 93% of cases and 84% of controls, and among cases 45% received XRT versus 44% of controls. Smoking increased the odds of lung cancer in women who did not receive XRT (OR = 6.0, 95%CI, 3.5–10.1) whereas XRT was not associated with increased odds (OR = 0.5, 95%CI, 0.2–1.1) in women who did not smoke. Overall the odds ratio for both XRT and smoking together compared with neither exposure was 9.00 (9 5% CI, 5.1–15.9). Similarly, when stratifying on laterality of the lung cancer in relation to the breast cancer, and when the time interval between breast and lung cancers was >10 years, there was an increased odds for both smoking and XRT together for lung cancers on the same side as the breast cancer (ipsilateral) (OR = 11.5, 95% CI, 4.9–27.8) and lung cancers on the opposite side of the breast cancer (contralateral) (OR= 9.6, 95% CI, 2.9–0.9). After 20 years the odds for the ipsilateral lung were even more pronounced (OR = 19.2, 95% CI, 4.2–88.4) compared to the contralateral lung (OR = 2.6, 95% CI, 0.2–2.1). In conclusion, smoking was a significant independent risk factor for lung cancer after breast cancer. Moreover, a greater than multiplicative effect was observed with smoking and XRT combined being especially evident after 10 years for both the ipsilateral and contralateral lung and after 20 years for the ipsilateral lung. ^