Karin C. Söderberg

Cohort studies of association between self‐reported allergic conditions, immune‐related diagnoses and glioma and meningioma risk

An inverse association between self‐reported allergies and glioma and meningioma risk, has been previously observed in case‐control studies. Approximately 27% (median) of the information on both glioma and meningioma in these studies, however, is collected from proxy respondents. In fact, the odds ratios (OR) among previous brain tumor studies are inversely related to the proportion of proxy respondents (Pearson correlation coefficient = −0.94; 95% CI = −1.00 to −0.65); this correlation suggests bias. We therefore constructed 3 cohorts based on the Swedish Twin, Hospital Discharge, and Cancer Registries. In Cohorts I (14,535 people developed 37 gliomas and 41 meningiomas) and II (29,573 people developed 42 gliomas and 26 meningiomas) median time from self‐report of allergies to brain tumor diagnosis was 15.4 years. Cohort III, which overlaps with Cohorts I and II (52,067 people developed 68 gliomas and 63 meningiomas), was linked to the Swedish Hospital Discharge Registry where pre‐brain tumor immune‐related discharge diagnoses were recorded. Allergies are inversely associated with glioma risk in Cohort I (Hazard ratio [HR] = 0.45; 95% CI = 0.19–1.07) and among high grade (III and IV, HR = 0.45; 95% CI = 0.11–1.92) but not low grade (I and II, HR = 2.60; 95% CI = 0.86–7.81) gliomas in Cohort II. In Cohort III, immune‐related discharge diagnoses are also inversely associated with glioma (HR = 0.46; 95% CI = 0.14–1.49). There is no strong evidence against (and some for) the hypothesis that allergies reduce glioma risk.

Parental Autoimmune Diseases Associated With Autism Spectrum Disorders in Offspring

Background: Autism spectrum disorders are often idiopathic. Studies have suggested associations between immune response and these disorders. We explored associations between parental autoimmune disorders and childrens diagnosis of autism by linking Swedish registries. Methods: Data for each participant were linked across 3 Swedish registries. The study includes 1227 cases and 25 matched controls for each case (30,693 controls with parental linkage). Parental diagnoses comprised 19 autoimmune disorders. We estimated odds ratios (ORs) using multivariable conditional logistic regression. Results: Parental autoimmune disorder was weakly associated with autism spectrum disorders in offspring (maternal OR = 1.6 [95% confidence interval = 1.1–2.2]; paternal OR = 1.4 [1.0–2.0]). Several maternal autoimmune diseases were correlated with autism. For both parents, rheumatic fever was associated with autism spectrum disorders. Conclusions: These data support previously reported associations between parental autoimmune disorders and autism spectrum disorders. Parental autoimmune disorders may represent a critical pathway that warrants more detailed investigation.

Allergic conditions and risk of hematological malignancies in adults: a cohort study.

BackgroundTwo contradictory hypotheses have been proposed to explain the relationship between allergic conditions and malignancies, the immune surveillance hypothesis and the antigenic stimulation hypothesis. The former advocates that allergic conditions may be protective against development of cancer, whereas the latter proposes an increased risk. This relationship has been studied in several case-control studies, but only in a few cohort studies.MethodsThe association between allergic conditions and risk of developing leukemia, Hodgkins disease, non-Hodgkins lymphoma and myeloma was investigated in a cohort of 16,539 Swedish twins born 1886–1925. Prospectively collected, self-reported information about allergic conditions such as asthma, hay fever or eczema was obtained through questionnaires administered in 1967. The cohort was followed 1969–99 and cancer incidence was ascertained from the Swedish Cancer Registry.ResultsHives and asthma tended to increase the risk of leukemia (relative risk [RR] = 2.1, 95% Confidence Interval [CI] 1.0–4.5 and RR = 1.6, 95% CI 0.8–3.5, respectively). There was also an indication of an increased risk of non-Hodgkins lymphoma associated with eczema during childhood (RR = 2.3, 95% CI 1.0–5.3).ConclusionIn contrast to most previous studies, our results do not indicate a protective effect of allergic conditions on the risk of developing hematological malignancies. Rather, they suggest that allergic conditions might increase the risk of some hematological malignancies.

Prior Hospitalization for Epilepsy, Diabetes, and Stroke and Subsequent Glioma and Meningioma Risk

We conducted a case-control study to evaluate the preclinical association between epilepsy, diabetes, and stroke and primary adult brain tumors. We first identified all 1,501 low-grade glioma, 4,587 high-grade glioma (HGG), and 4,193 meningioma cases reported to the Swedish Cancer Registry from 1987 to 1999. Next, controls (137,485) were randomly selected from the continuously updated Swedish Population Registry and matched to cases diagnosed that year on age and sex. Finally, cases and controls were linked to the Swedish Hospital Discharge Registry (1969-1999). We found that ≥8 years before HGG diagnosis (or control reference year) there was an elevated risk of HGG among people discharged with epilepsy [odds ratio (OR), 3.01; 95% confidence interval (95% CI), 1.73-5.22]. Two to 3 years before HGG diagnosis, this risk increased (OR, 5.33; 95% CI, 3.58-7.93) and was especially strong among people ages <55 years (OR, 13.49; 95% CI, 6.99-25.94). During this 2- to 3-year prediagnostic period, we also found an increased risk of HGG among people discharged with meningitis (OR, 3.02; 95% CI, 1.06-8.59) or viral encephalitis (OR, 12.64; 95% CI, 2.24-71.24). Results are similar for glioblastoma multiforme, low-grade glioma, and meningioma. In contrast, risk of HGG among people discharged with diabetes or stroke does not increase until year of brain tumor diagnosis. The occurrence of excess epilepsy ≥8 years before HGG diagnosis suggests a relatively long preclinical phase, but excess diabetes or stroke appear late in HGG development.

Overweight, obesity and risk of haematological malignancies: a cohort study of Swedish and Finnish twins.

BACKGROUND Obesity is related to an increased risk of several forms of cancer. However, findings from studies on haematological malignancies are inconsistent. METHODS We used prospectively collected data from two Swedish twin cohorts and the Finnish Twin Cohort (in total 70,067 persons) to study the effects of overweight and obesity on the development of leukaemia, non-Hodgkin lymphoma, Hodgkins lymphoma and myeloma. The cohorts were followed from baseline through 2002 (Sweden) and through 2004 (Finland). RESULTS We found a risk increase of myeloma with a relative risk (RR) of 2.1 (95% confidence interval [CI] 1.1-3.7) among obese persons, a RR of 2.5 (1.0-6.2) for chronic myeloid leukaemia and a RR of 2.7 (0.8-9.6) for acute lymphoblastic leukaemia among overweight persons as compared to normal-weighted ones. CONCLUSIONS Our results add further evidence suggesting that overweight and obesity may have an impact on some haematological malignancies, in particular myeloma.

Co-twin control and cohort analyses of body mass index and height in relation to breast, prostate, ovarian, corpus uteri, colon and rectal cancer among Swedish and Finnish twins

Associations between anthropometric measures and cancer have been studied previously, but relatively few studies have had the opportunity to control for genetic and early shared environmental factors. In this study, we analyzed 2 twin cohorts from Sweden born 1886–1925 (n = 21,870) and 1926–1958 (n = 30,279) and 1 from Finland born 1880–1958 (n = 25,882) including in total 78,031 twins, and studied the association between BMI and height and risk of prostate, breast, ovarian, corpus uteri, colon and rectal cancer. The cohorts were both analyzed through a co‐twin control method and as traditional cohorts. In co‐twin control analyses, older obese (BMI ≥ 30 kg/m2) subjects (median age 56 years at baseline) were at higher risk of cancer of the corpus uteri (OR = 3.0; 95% CI 0.9–10.6), colon (OR = 1.9; 95% CI 0.8–4.5) and breast (OR = 2.5; 95% CI 1.3–4.2). For younger obese women (median age 30 years at baseline), an inverse tendency was observed for breast cancer (OR = 0.6; 95% CI 0.3–1.5, p for trend = 0.05). The tallest women had an increased risk of breast (OR = 1.8; 95% CI 1.3–2.7) and ovarian cancer (OR = 1.7; 95% CI 0.8–3.5). No consistent associations were found for prostate cancer either for BMI or height. There are some suggestions in our study that uncontrolled genetic or early shared environmental factors may affect risk estimates in studies of anthropometric measures and cancer risk, but do not explain observations of increased cancer risks related to BMI or height.

Childhood leukemia and magnetic fields in infant incubators.

In studies of magnetic field exposure and childhood leukemia, power lines and other electrical installations close to the children’s homes constitute the most extensively studied source of exposure. We conducted a study to assess whether exposure to magnetic fields in infant incubators is associated with an increased leukemia risk. We identified all children with leukemia born in Sweden between 1973 and 1989 from the national Cancer Registry and selected at random one control per case, individually matched by sex and time of birth, from the study base. We retrieved information about treatment in infant incubators from medical records. We made measurements of the magnetic fields inside the incubators for each incubator model kept by the hospitals. Exposure assessment was based on measurements of the magnetic field level inside the incubator, as well as on the length of treatment. For acute lymphoblastic leukemia, the risk estimates were close to unity for all exposure definitions. For acute myeloid leukemia, we found a slightly elevated risk, but with wide confidence intervals and with no indication of dose response. Overall, our results give little evidence that exposure to magnetic fields inside infant incubators is associated with an increased risk of childhood leukemia.