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Background: Epithelial ovarian cancer is associated with reproductive factors, but we lack knowledge if hormonal factors during pregnancy influence the mother's risk. Because pregnancy hormones are primarily produced by the placenta, placental weight may be an indirect marker of hormone exposure during pregnancy., Methods: In a nationwide Swedish cohort study, we included women with singleton births from 1982 to 1989. Women were followed for occurrence of invasive epithelial ovarian cancer, death, or emigration through 2004. Hazard ratios (HR) with 95% confidence intervals (95% CI) from Cox models were used to estimate associations between pregnancy exposures and epithelial ovarian cancer., Results: Among 395,171 women with information on placental weight in their first recorded birth, 316 women developed invasive epithelial ovarian cancer. Mean age at diagnosis was 44 years. Compared with women with a placental weight of 500 to 699 g, women with a high (>or=700 g) placental weight had an increased risk of developing epithelial ovarian cancer (HR, 1.47; 95% CI, 1.14-1.90). Compared with women with term pregnancies (40-41 weeks), women with post-term (>or=42 weeks) pregnancies had an increased risk of developing epithelial ovarian cancer (HR, 1.48; 95% CI, 1.00-2.19). These associations were slightly stronger when we included information about women's overall first birth, and slightly weaker when we included information about last recorded birth or ever last birth from 1982 to 1989., Conclusions: Because pregnancy hormone levels increase with placental weight, our study supports the hypothesis that hormone exposures during pregnancy influence the risk of invasive epithelial ovarian cancer among young women.

Scandinavian moist snuff (snus) is claimed to be a safer alternative to smoking. We aimed to quantify cancer incidence among male snus users and to shed light on the net health outcome by studying their overall mortality. A cohort, comprised of 9,976 men who participated in a population-based survey, was compiled in 1973-74. Follow-up until January 31, 2002, was accomplished through record-linkages with nation-wide and essentially complete registers of demographics, cancer and causes of deaths. Adjusted relative risks among exposed relative to unexposed men were estimated using Cox proportional hazards regression. The cohort members contributed more than 220,000 person-years at risk for cancer. A statistically significant increase in the incidence of the combined category of oral and pharyngeal cancer among daily users of snus (incidence rate ratio 3.1, 95% confidence interval 1.5-6.6) was found. Overall mortality was also slightly increased (hazard ratio 1.10, 95% confidence interval 1.01-1.21). Although the combined previous literature on snus and oral cancer weigh toward no association, this population-based prospective study provided suggestive evidence of snus-related risks that cannot be lightly ignored., ((c) 2008 Wiley-Liss, Inc.)

Snus-induced lesions (SILs) are mucosal changes that are regularly seen in users of moist snuff (snus). Their role in oral carcinogenesis remains undefined. Our aim was to assess the natural course of SILs over several decades. A cohort of 1,115 individuals with SILs, confirmed in 1973-1974 during a population-based survey was followed for 27-29 years through multiple record linkages with virtually complete population- and health registers. A sample (n = 267) of the cohort members were invited for reexamination after 19-22 years. Register-based follow-up through January 2002 revealed a total of 3 incident cases of oral cancer (standardized incidence ratio of 2.3, 95% CI 0.5-6.7), none of which occurred at the site of the original SIL. There was a strong association noted between the degree of SIL and current snus consumption. The SILs had disappeared in all 62 individuals who had permanently quit using snus. In no case did we observe an important clinical change for the worse among individuals who had decreased their use or continued unabatedly. While the incidence of oral cancer in this cohort of individuals with SILs tended to be higher than expected, we conclude that cancers rarely occur at the site of lesions observed in the distant past., (2006 Wiley-Liss, Inc.)

Background: The accuracy of maternal self-reported smoking information, especially exposure to environmental tobacco smoke, has been questioned. This study aimed to validate self-reported smoking, smoking cessation, and environmental tobacco smoke exposure in early and late pregnancy, using the biomarker cotinine as the gold standard., Methods: Prospective cohort study of 953 pregnant Swedish women between 1996 and 1998. In-person interviews and cotinine measurements were performed at 6-12 and 31-34 completed weeks of gestation. All women were asked about nicotine exposures throughout pregnancy, including cigarette smoking, oral snuff, nicotine replacement therapy, and environmental tobacco smoke exposure., Results: The validity of self-reported daily smoking was high in early and late pregnancy. However, among women reporting smoking cessation before the first interview and between the first and second interviews, 13% and 25% misreported active smoking, respectively. According to cotinine measurements, 22% of non-smoking women were exposed to environmental tobacco smoke in early pregnancy, and 8% were exposed in late pregnancy. Self-reported information on environmental tobacco smoke exposure in early and late pregnancy misclassified most exposed women as unexposed., Conclusion: The results of this study indicate that self-reported smoking information among pregnant women can be trusted. However, among women reporting smoking cessation during pregnancy, the misclassification rate increased with recency of quitting. Environmental tobacco smoke exposure was common among non-smokers, and the low validity of self-reported environmental tobacco smoke exposure suggests that future studies on environmental tobacco smoke exposure and risks of pregnancy outcomes may have to rely on biomarker assessments.

Background: The increase in esophageal adenocarcinoma incidence in developed countries remains unexplained. Although low socioeconomic status (SES) is linked to an increased risk of esophageal squamous cell carcinoma (SCC), the relation with adenocarcinoma is uncertain., Methods: We addressed the importance of various socioeconomic factors in a Swedish population-based case-control study, where 189 and 262 cases of esophageal adenocarcinoma and the gastric cardia, respectively, 167 cases of esophageal SCC, and 820 control participants underwent personal interviews. Our classification of SES was derived from occupational histories. Relative risks were estimated by odds ratios with 95% confidence intervals (95% CI), derived from conditional logistic regression, in crude and adjusted models., Results: The risk of both esophageal adenocarcinoma and SCC increased with decreasing SES; unskilled workers had 3.7-fold (95% CI, 1.7-7.7) and 2.1-fold (95% CI, 1.0-4.7) increased risks, respectively, compared with age- and sex-comparable professionals. Adjustment for reflux symptoms, body mass, and tobacco smoking attenuated the excess risk for esophageal adenocarcinoma, whereas adjustment for Helicobacter pylori infection in a subset of the interviewed participants did not influence the results. Life without a partner was associated with a >2-fold increased risk of both histologic types of esophageal cancer, associations that remained even after multiple adjustments., Conclusions: Esophageal adenocarcinoma and SCC are both linked to low SES and a life without a partner. These associations are only partly explained by established risk factors.

Purpose: To analyze the risk of cognitive impairment among female Swedish Twins with regard to endogenous and exogenous hormone exposure., Design and Setting: A cross-sectional analysis of data from the HARMONY Study, a population-based cohort study of cognitive impairment in the Swedish Twin Registry., Methods: Information regarding age at menarche and menopause, parity, and length and type of hormone therapy (HT) was collected via a telephone interview from 6604 women, aged 65-84. Cognitive impairment was assessed with the TELE, a brief telephone cognitive screen., Results: Length of reproductive period was inversely associated with risk of cognitive impairment (p<0.01). The OR was 1.15 (CI 95% 0.96-1.36) for women with reproductive periods <35 years and 0.82 (CI 95% 0.66-1.00) for women with reproductive periods >39 years. Age at menopause was inversely associated with risk of cognitive impairment. Use of HT was associated with average 40% decline in the risk of cognitive impairment, independent of type and timing of treatment., Conclusion: Our results suggest that both increased length of reproductive period and HT are associated with reduced risk of cognitive impairment.

Objective: To describe the magnitude of change in the proportion of term and postterm (37 completed weeks or more) large for gestational age (LGA) infants between 1992-2001 in Sweden and to examine whether time trends in prevalence of LGA births can be explained by changes in maternal risk factors., Methods: Using the population-based Swedish Birth Register, we analyzed data from 1992 through 2001 on births of women who delivered live, singleton, term infants without malformations (N = 874,163). Unconditional logistic regression was used to model the odds of LGA birth., Results: Mean birth weight and proportions of LGA births and births 4,500 g or more rose during the period 1992 to 2001. An unadjusted analysis estimated that the risk of LGA birth increased by 23% over 10 years. However, the prevalence of overweight and obesity (body mass index of 25 or greater) increased from 25% to 36%, and the prevalence of smoking decreased from 23% to 11% during the same period. After adjusting trends in all covariates simultaneously, the association between risk of LGA birth and calendar year disappeared., Conclusion: The increasing proportions of LGA births over time is explained by concurrent increases in maternal body mass index and decreases in maternal smoking. With the increasing prevalence of overweight among adolescents and young women, the prevalence of LGA infants and associated risks may increase over time., Level of Evidence: II-2

Background: For reasons yet unknown, the incidence of esophageal and gastric cardia adenocarcinoma is increasing rapidly and moderately, respectively. These tumors occur predominantly among males. We hypothesized that stressful psychosocial working conditions might be involved in the etiology of these cancers., Objective: To study if job strain, work pace satisfaction and coping are linked to the risk of esophageal or cardia cancers., Methods: A nationwide Swedish population-based case-control study including 189 and 262 esophageal and cardia adenocarcinoma cases, respectively, 167 esophageal squamous-cell carcinoma cases, and 820 controls. All study subjects were interviewed. The relative risk was estimated using odds ratios, with 95% confidence intervals, adjusted for potential confounders., Results: We found no statistically significant associations between two different measures of job strain and the three cancer types, except between one job strain measure and risk of cardia adenocarcinoma (OR: 2.2; 95% CI: 1.0-4.8). There was a moderately strong association between having a covert coping style, compared to an overt, and risk of both esophageal (OR: 1.8; 95% CI: 1.2-2.8) and cardia adenocarcinoma (OR: 1.5; 95% CI: 1.0-2.3). Among subjects reporting low work pace satisfaction we found an almost 4-fold increased risk of esophageal squamous-cell carcinoma (OR: 3.8; 95% CI: 1.3-11.0), and a nearly 3-fold increased risk of esophageal adenocarcinoma (OR: 2.8; 95% CI: 1.1-7.0)., Conclusions: Work-related stress does not seem to be of importance in the etiology of adenocarcinoma of the esophagus or the gastric cardia. However, the interaction of a stressful work environment and the individual's responses to it may be associated with a moderately increased risk of these cancer types.