Measurements and determinants of children's exposure to background gamma radiation in Switzerland.

Epidemiological studies of children's cancer risks associated with background gamma radiation exposure have used geographic exposure models to estimate exposure at their locations of residence. We measured personal exposure to background gamma radiation, and we investigated the extent to which it was associated with children's whereabouts. We collected data on whereabouts and exposure to background gamma radiation over a 5-day period among children aged 4-15 years in Switzerland. We used D-Shuttle dosimeters to measure children's exposure, and we asked parents to write their children's activities in diaries. We used Poisson mixed-effects and linear regression models to investigate the association of hourly and overall doses, respectively, with children's reported whereabouts. During the observed time, 149 participating children spent 66% indoors at home; 19% indoors away from home; and 15% outdoors. The mean personal exposure was 85.7 nSv/h (range 52.3 nSv/h-145 nSv/h). Exposure was 1.077 (95% CI 1.067, 1.087) times higher indoors than outdoors and varied by building material and (predicted) outdoor dose rates. Our study provides detailed information about children's patterns of exposure to background gamma radiation in Switzerland. Dwelling building materials and outdoor dose rates are important determinants of children's exposure. Future epidemiological studies may benefit from including information about building materials

Bayesian spatial modelling of terrestrial radiation in Switzerland

The geographic variation of terrestrial radiation can be exploited in epidemiological studies of the health effects of protracted low-dose exposure. Various methods have been applied to derive maps of this variation. We aimed to construct a map of terrestrial radiation for Switzerland. We used airborne $\gamma$-spectrometry measurements to model the ambient dose rates from terrestrial radiation through a Bayesian mixed-effects model and conducted inference using Integrated Nested Laplace Approximation (INLA). We predicted higher levels of ambient dose rates in the alpine regions and Ticino compared with the western and northern parts of Switzerland. We provide a map that can be used for exposure assessment in epidemiological studies and as a baseline map for assessing potential contamination.Comment: 27 pages, 10 figure

Bayesian spatial modelling of terrestrial radiation in Switzerland

The geographic variation of terrestrial radiation can be exploited in epidemiological studies of the health effects of protracted low-dose exposure. Various methods have been applied to derive maps of this variation. We aimed to construct a map of terrestrial radiation for Switzerland. We used airborne γ-spectrometry measurements to model the ambient dose rates from terrestrial radiation through a Bayesian mixed-effects model and conducted inference using Integrated Nested Laplace Approximation (INLA). We predicted higher levels of ambient dose rates in the alpine regions and Ticino compared with the western and northern parts of Switzerland. We provide a map that can be used for exposure assessment in epidemiological studies and as a baseline map for assessing potential contamination

External background ionizing radiation and childhood cancer: Update of a nationwide cohort analysis.

BACKGROUND Exposure to high doses of ionizing radiation is known to cause cancer. Exposure during childhood is associated with a greater excess relative risk for leukemia and tumors of the central nervous system (CNS) than exposure in later life. Cancer risks associated with low-dose exposure (<100 mSv) are uncertain. We previously investigated the association between the incidence of childhood cancer and levels of exposure to external background radiation from terrestrial gamma and cosmic rays in Switzerland using data from a nationwide census-based cohort study. Here, we provide an update of that study using an extended follow-up period and an improved exposure model. METHODS We included all children 0-15 years of age registered in the Swiss national censuses 1990, 2000, and 2010-2015. We identified incident cancer cases during 1990-2016 using probabilistic record linkage with the Swiss Childhood Cancer Registry. Exposure to terrestrial and cosmic radiation at children's place of residence was estimated using geographic exposure models based on aerial spectrometric gamma-ray measurements. We estimated and included the contribution from 137Cs deposition after the Chernobyl accident. We created a nested case-control sample and fitted conditional logistic regression models adjusting for sex, year of birth, neighborhood socioeconomic position, and modelled outdoor NO2 concentration. We also estimated the population attributable fraction for childhood cancer due to external background radiation. RESULTS We included 3,401,113 children and identified 3,137 incident cases of cancer, including 951 leukemia, 495 lymphoma, and 701 CNS tumor cases. Median follow-up in the cohort was 6.0 years (interquartile range: 4.3-10.1) and median cumulative exposure since birth was 8.2 mSv (range: 0-31.2). Hazard ratios per 1 mSv increase in cumulative dose of external background radiation were 1.04 (95% CI: 1.01-1.06) for all cancers combined, 1.06 (1.01-1.10) for leukemia, 1.03 (0.98-1.08) for lymphoma, and 1.06 (1.01-1.11) for CNS tumors. Adjustment for potential confounders had little effect on the results. Based on these results, the estimated population attributable fraction for leukemia and CNS tumors due to external background radiation was 32% (7-49%) and 34% (5-51%), respectively. CONCLUSIONS Our results suggest that background ionizing radiation contributes to the risk of leukemia and CNS tumors in children

Epidemiological studies of natural sources of radiation and childhood cancer: current challenges and future perspectives.

Empirical estimation of cancer risks in children associated with low-dose ionizing radiation (<100 mSv) remains a challenge. The main reason is that the required combination of large sample sizes with accurate and comprehensive exposure assessment is difficult to achieve. An international scientific workshop "Childhood cancer and background radiation" organised by the Institute of Social and Preventive Medicine of the University of Bern brought together researchers in this field to evaluate how epidemiological studies on background radiation and childhood cancer can best improve understanding of the effects of low-dose ionising radiation. This review summarises and evaluates the findings of the existing studies in the light of their methodological differences, identifies key limitations and challenges and proposes ways forward. Large childhood cancer registries, such as those in Great Britain, France and Germany, now allow the conducting of studies that should have sufficient statistical power to detect the effects predicted by standard risk models. Nevertheless, larger studies or pooled studies will be needed to investigate disease subgroups. The main challenge is to accurately assess children's individual exposure to radiation from natural sources and from other sources, as well as potentially confounding non-radiation exposures, in such large study populations. For this, the study groups should learn from each other to improve exposure estimation and develop new ways to validate exposure models with personal dosimetry

Neoadjuvant nivolumab + palbociclib + anastrozole for oestrogen receptor-positive/human epidermal growth factor receptor 2-negative primary breast cancer: Results from CheckMate 7A8

Background: Preclinical data suggest synergistic activity with the combination of programmed death-1 and cyclin-dependent kinase 4/6 blockade in oestrogen receptor-positive/human epidermal growth factor 2-negative (ER+/HER2–) breast cancer. The noncomparative phase 1b/2 CheckMate 7A8 study (NCT04075604) evaluated neoadjuvant treatment with nivolumab, palbociclib, and anastrozole in patients with ER+/HER2− breast cancer. Here, we report outcomes from the safety run-in phase. Methods: Patients with histologically confirmed, untreated ER+/HER2− breast cancer, primary tumour ≥2 cm, ECOG performance status ≤1, and eligible for post-treatment surgery received nivolumab 480 mg intravenously every 4 weeks, palbociclib 125 mg or 100 mg orally once daily for 3 weeks per cycle, and anastrozole 1 mg orally once daily for five 4-week cycles, or until disease progression. The primary endpoint was the proportion of patients with dose-limiting toxicities (DLTs) within 4 weeks of treatment initiation. Results: At safety data review, 21 patients were treated (palbociclib 125-mg group: n = 9; palbociclib 100-mg group: n = 12). DLTs were reported in 2 (22.2%) and 0 patients in the palbociclib 125-mg and 100-mg groups, respectively. Across both groups, 9 patients discontinued treatment due to toxicity (grade 3/4 hepatic adverse events [n = 6], grade 3 febrile neutropaenia [n = 1], grade 1 pneumonitis [n = 1], and grade 3 rash and grade 2 immune-mediated pneumonitis [n = 1]). Consequently, the study was closed early. Conclusions: Neoadjuvant treatment with nivolumab, palbociclib, and anastrozole showed a high incidence of grade 3/4 hepatotoxicity and treatment discontinuation, indicating that this combination should not be further pursued for treatment of primary ER+/HER2− breast cancer