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Purpose: Uterine sarcomas are a rare group of uterine malignancies. Due to the low incidence and changes in uterine sarcoma classification, risk factors are not well characterized. Our objective was to evaluate risk factors for uterine sarcoma and compare risk factors between uterine sarcoma, malignant mixed Mullerian tumors (MMMTs), and type I endometrial carcinomas., Methods: This nested case-control study utilized linked data from population-based medical birth and cancer registries in Denmark, Finland, Norway, and Sweden. Up to 10 controls were matched on country and birth year for each uterine cancer case. Using multivariable adjusted multinomial logistic regression, estimates of the associations between pregnancy-related factors and risk of uterine sarcoma, MMMTs, and type I endometrial carcinomas were determined., Results: Having a very-low-birth-weight infant (< 1500 vs. 2500-3999 g: OR [95% CI] 2.83 [1.61-4.96]) was associated with an increased risk of uterine sarcoma. Whereas, having a more recent pregnancy was associated with reduced risks of MMMT (< 10 vs. ≥ 30 years: 0.66 [0.20-2.23]) and type 1 endometrial carcinomas (0.35 [0.30-0.41]) but not uterine sarcomas (1.33 [0.90-1.98], p-heterogeneity < 0.01)., Conclusion: Our study provides evidence that risk factors for uterine sarcoma and MMMT, previously grouped with uterine sarcomas, vary substantially. Additionally, MMMT and type I endometrial carcinomas are more similar than uterine sarcoma in that pregnancy complications like gestational hypertension and preeclampsia were associated with reduced risks of both but not uterine sarcoma, suggesting different etiologies., (© 2023. This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply.)

Background: Most anti-tumour necrosis factor (anti-TNF) agents are transferred across the placenta and may increase paediatric susceptibility to infections., Aims: To assess the risk of paediatric infections after maternal anti-TNF treatment., Methods: Population-based cohort study in Denmark, Finland and Sweden 2006-2013 in which 1027 children born to women with rheumatoid arthritis, psoriasis, psoriatic arthritis, ankylosing spondylitis or inflammatory bowel disease, treated with anti-TNF, and 9346 children to women with non-biologic systemic treatment, were compared to 1 617 886 children of the general population. Children were followed for 3 years., Results: Adjusted by maternal age, parity, smoking, body mass index, country and calendar year, the incidence rate ratios with 95% confidence interval (CI) for hospital admissions for infection in the first year were 1.43 (1.23-1.67) for anti-TNF and 1.14 (1.07-1.21) for non-biologic systemic treatment, and 1.29 (1.11-1.50) and 1.09 (1.02-1.15), respectively, when additionally adjusting for adverse birth outcomes. There was a slight increase in antibiotic prescriptions in the second year for anti-TNF, 1.19 (1.11-1.29), and for non-biologic systemic treatment, 1.10 (1.07-1.13). There was no difference among anti-TNF agents, treatment in the third trimester, or between mono/combination therapy with non-biologic systemic treatment., Conclusions: Both anti-TNF and non-biologic systemic treatment were associated with an increased risk of paediatric infections. However, reassuringly, the increased risks were present regardless of treatment in the third trimester, or with combination treatment, and were not persistent during the first 3 years of life. Our findings may indicate a true risk, but could also be due to unadjusted confounding by disease severity and healthcare-seeking behaviour. This may in turn shift the risk-benefit equation towards continuation of treatment even in the third trimester., (© 2020 The Authors. Alimentary Pharmacology & Therapeutics published by John Wiley & Sons Ltd.)

Purpose: To study the risk of preterm birth, caesarean section, and small for gestational age after anti-tumor necrosis factor agent treatment (anti-TNF) in pregnancy., Methods: Population-based study including women with inflammatory bowel disease, rheumatoid arthritis, ankylosing spondylitis, psoriatic arthritis, and psoriasis, and their infants born 2006 to 2013 from the national health registers in Denmark, Finland, and Sweden. Women treated with anti-TNF were compared with women with nonbiologic systemic treatment. Adalimumab, etanercept, and infliximab were compared pairwise. Continuation of treatment in early pregnancy was compared with discontinuation. Odds ratios with 95% confidence intervals were calculated in logistic regression models adjusted for country and maternal characteristics., Results: Among 1 633 909 births, 1027 infants were to women treated with anti-TNF and 9399 to women with nonbiologic systemic treatment. Compared with non-biologic systemic treatment, women with anti-TNF treatment had a higher risk of preterm birth, odds ratio 1.61 (1.29-2.02) and caesarean section, 1.57 (1.35-1.82). The odds ratio for small for gestational age was 1.36 (0.96-1.92). In pairwise comparisons, infliximab was associated with a higher risk of severely small for gestational age for inflammatory joint and skin diseases but not for inflammatory bowel disease. Discontinuation of anti-TNF had opposite effects on preterm birth for inflammatory bowel disease and inflammatory joint and skin diseases., Conclusions: Anti-TNF agents were associated with increased risks of preterm birth, caesarean section, and small for gestational age. However, the diverse findings across disease groups may indicate an association related to the underlying disease activity, rather than to agent-specific effects., (© 2020 John Wiley & Sons, Ltd.)

Epithelial ovarian cancer is a fatal disease of largely unknown etiology. Higher parity is associated with reduced risk of ovarian cancer. However, among parous women, the impact of pregnancy-related factors on risk is not well understood. This population-based case-control study included all parous women with epithelial ovarian cancer in Denmark, Finland, Norway and Sweden during 1967-2013 (n = 10,957) and up to 10 matched controls (n = 107,864). We used conditional logistic regression to estimate odds ratios (ORs) with 95% confidence intervals (CIs) for pregnancy-related factors and ovarian cancer risk by histological subtype. Preterm delivery was associated with an increased risk [pregnancy length (last pregnancy) ≤30 vs. 39-41 weeks, OR 1.33 (95% CI 1.06-1.67), adjusted for number of births]; the OR increased as pregnancy length decreased (p for trend < 0.001). Older age at first and last birth was associated with a decreased risk [first birth: 30-39 vs. <25 years: adjusted OR 0.76 (95% CI 0.70-0.83); last birth 30-39 vs. <25 years: adjusted OR 0.76 (95% CI 0.71-0.82)]. Increasing number of births was protective [≥4 births vs. 1; OR 0.63 (95% CI 0.59-0.68)] for all subtypes, most pronounced for clear-cell tumors [OR 0.30, (95% CI 0.21-0.44), p heterogeneity  < 0.001]. No associations were observed for multiple pregnancies, preeclampsia or offspring size. In conclusion, in addition to high parity, full-term pregnancies and pregnancies at older ages were associated with decreased risk of ovarian cancer. Our findings favor the cell clearance hypothesis, i.e. a recent pregnancy provides protection by clearing of precancerous cells from the epithelium of the ovary/fallopian tubes, mediated by placental or ovarian hormones., (© 2018 UICC.)

Certain features of pregnancy are important risk factors for breast cancer, such as protection afforded by young age at first birth. Preeclampsia, a pregnancy complication, is associated with reduced maternal breast cancer risk. However, questions remain regarding causality, biological mechanisms and the relation of other hypertensive conditions to risk. We conducted a population-based case-control study of breast cancer cases (n = 116,196) in parous women identified through linkage of birth and cancer registries in Denmark, Finland, Norway and Sweden (1967-2013), including up to 10 matched controls per case (n = 1,147,192) sampled from the birth registries (complete data were not available on all variables). Odds ratios (ORs) with 95% confidence intervals (CIs) were derived from unconditional logistic regression models including matching factors (country, maternal birth year) and parity. Hypertension diagnosed before pregnancy (OR 0.87; 95% CI 0.78-0.97), gestational hypertension (OR 0.90; 95% CI 0.86-0.93) and preeclampsia (OR 0.91; 95% CI 0.88-0.95) were associated with reduced breast cancer risk. Results remained similar after adjustment for smoking and maternal body mass index before first pregnancy, and were generally similar stratified by parity, age at breast cancer diagnosis, time since first and last birth, sex of the offspring and calendar time. Except for retained placenta (OR 1.14; 95% CI 0.98-1.32), no other pregnancy complication appeared associated with breast cancer risk. The mechanisms mediating the modest risk reductions for history of preeclampsia or hypertension preceding or arising during pregnancy, and possible increased risk with history of retained placenta are unknown and warrant further laboratory, clinical and epidemiological investigation., (© 2018 UICC.)

Objective: The etiology of childhood cancers is largely unknown. Studies have suggested that birth characteristics may be associated with risk. Our goal was to evaluate the risk of childhood cancers in relation to fetal growth., Methods: We conducted a case-control study nested within Nordic birth registries. The study included cancer cases diagnosed in Denmark, Finland, Norway, and Sweden among children born from 1967 to 2010 and up to 10 matched controls per case, totaling 17,698 cases and 172,422 controls. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were derived from conditional logistic regression., Results: Risks of all childhood cancers increased with increasing birth weight (P trend ≤ .001). Risks of acute lymphoid leukemia and Wilms tumor were elevated when birth weight was >4000 g and of central nervous system tumors when birth weight was >4500 g. Newborns large for gestational age were at increased risk of Wilms tumor (OR: 2.1 [95% CI: 1.2-3.6]) and connective/soft tissue tumors (OR: 2.1 [95% CI: 1.1-4.4]). In contrast, the risk of acute myeloid leukemia was increased among children born small for gestational age (OR: 1.8 [95% CI: 1.1-3.1]). Children diagnosed with central nervous system tumors at <1 year of age had elevated risk with increasing head circumference (P trend < .001). Those with head circumference >39 cm had the highest risk (OR: 4.7 [95% CI: 2.5-8.7])., Conclusions: In this large, Nordic population-based study, increased risks for several childhood tumors were associated with measures of fetal growth, supporting the hypothesis that tumorigenesis manifesting in childhood is initiated in utero.

Purpose: All five Nordic countries have nationwide prescription databases covering all dispensed drugs, with potential for linkage to outcomes. The aim of this review is to present an overview of therapeutic areas studied and methods applied in pharmacoepidemiologic studies using data from these databases., Methods: The study consists of a Medline-based structured literature review of scientific papers published during 2005-2010 using data from the prescription databases in Denmark, Finland, Iceland, Norway, and Sweden, covering 25 million inhabitants. Relevant studies were analyzed in terms of pharmacological group, study population, outcomes examined, type of study (drug utilization vs. effect of drug therapy), country of origin, and extent of cross-national collaboration., Results: A total of 515 studies were identified. Of these, 262 were conducted in Denmark, 97 in Finland, 4 in Iceland, 87 in Norway, and 61 in Sweden. Four studies used data from more than one Nordic country. The most commonly studied drugs were those acting on the nervous system, followed by cardiovascular drugs and gastrointestinal/endocrine drugs. A total of 228 studies examined drug utilization and 263 focused on the effects and safety of drug therapy. Pregnant women were the most commonly studied population in safety studies, whereas prescribers' adherence to guidelines was the most frequent topic of drug utilization studies., Conclusions: The Nordic prescription databases, with their possibility of record-linkage, represent an outstanding resource for assessing the beneficial and adverse effects of drug use in large populations, under routine care conditions, and with the potential for long-term follow-up., (Copyright © 2013 John Wiley & Sons, Ltd.)

Introduction: In contrast to research in adults, there have been limited studies on testicular germ-cell cancer among boys aged <15 years. The aim of the study was to investigate the association between perinatal characteristics and childhood testicular germ-cell cancer., Methods: We identified 152 patients with childhood germ-cell cancer among boys (<15 years) born in Norway, Sweden, Finland and Denmark between 1967 and 2006 using the cancer and medical birth registries. For each case we sampled 10 population controls matched on year and country of birth. We used conditional logistic regression analysis to estimate odds ratios for cancer risk., Results: There was a weak, positive association between high (≥4000 g) birth weight and childhood testicular germ-cell cancer (adjusted OR=1.25; 95% CI: 0.83-1.90) compared with normal birth weight, and a correspondingly elevated risk for low birth weight (adjusted OR=1.41; 95% CI: 0.43-4.56). For Ponderal Index (PI) there was an increased risk for low and high values compared to those in the middle category (adjusted OR=1.64; 95% CI: 1.03-2.62 and 1.67; 95% CI: 0.93-2.99), respectively. There was no association between birth length and childhood testicular germ-cell cancer. The adjusted OR for testicular cancer among first born was 1.40; 95% CI: 0.96-2.05. Greater maternal age and less maternal education appeared to increase the risk, but the estimates were not statistically significant., Conclusion: We found a U-shaped association between fetal growth, measured as the PI, and childhood testicular germ-cell cancer. Our findings support the notion that abnormal fetal growth rate confers a risk in pediatric testicular cancer [corrected]., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

The Nordic countries have a long tradition of registry-based epidemiological research. Many population-based health registries were established in the 1960s, with use of unique personal identifiers facilitating linkage between registries. In recent years, each country has established a national database to track prescription drugs dispensed to individuals in ambulatory care. The objectives were to present an overview of the prescription databases established in the Nordic countries, as well as to elaborate on their unique potential for record linkage and cross-national comparison of drug utilization. Five Nordic countries collect drug exposure data based on drugs dispensed at pharmacies and have the potential to link these data to health outcomes. The databases together cover 25 million inhabitants (Denmark: 5.5 million; Finland: 5.3 million; Iceland: 0.3 million; Norway: 4.8 million; and Sweden: 9.2 million). In 2007, the registries encompassed 17 million prescription drug users (68% of the total population). We provide examples of how these databases have been used for descriptive drug utilization studies and analytical pharmacoepidemiological studies linking drug exposure to other health registries. Comparisons are facilitated by many similarities among the databases, including data source, content, coverage and methods used for drug utilization studies and record linkage. There are, however, some differences in coding systems and validity, as well as in some access and technical issues. To perform cross-national pharmacoepidemiological studies, resources, networks and time are needed, as well as methods for pooling data. Interpretation of results needs to account for inter-country heterogeneity and the possibility of spurious relationships. The Nordic countries have a unique potential for collaborative high-quality cross-national pharmacoepidemiological studies with large populations. This research may assist in resolving safety issues of international interest, thus minimizing the risk of either over-reacting on possible signals or underestimating drug safety issues.