Risk of primary childhood brain tumors related to season of birth in Kumamoto Prefecture, Japan

Characterizing light-dark cycles in the Neonatal Intensive Care Unit: a retrospective observational study

Objectives: To characterize bedside 24-h patterns in light exposure in the Neonatal Intensive Care Unit (NICU) and to explore the environmental and individual patient characteristics that influence these patterns in this clinical setting. Methods: We conducted a retrospective cohort study that included 79 very preterm infants who stayed in an incubator with a built-in light sensor. Bedside light exposure was measured continuously (one value per minute). Based on these data, various metrics (including relative amplitude, intradaily variability, and interdaily stability) were calculated to characterize the 24-h patterns of light exposure. Next, we determined the association between these metrics and various environmental and individual patient characteristics. Results: A 24-h light-dark cycle was apparent in the NICU with significant differences in light exposure between the three nurse shifts (p < 0.001), with the highest values in the morning and the lowest values at night. Light exposure was generally low, with illuminances rarely surpassing 75 lux, and highly variable between patients and across days within a single patient. Furthermore, the season of birth and phototherapy had a significant effect on 24-h light-dark cycles, whereas no effect of bed location and illness severity were observed. Conclusion: Even without an official lighting regime set, a 24-h light-dark cycle was observed in the NICU. Various rhythmicity metrics can be used to characterize 24-h light-dark cycles in a clinical setting and to study the relationship between light patterns and health outcomes.

Perinatal photoperiod and childhood cancer: pooled results from 182,856 individuals in the international childhood cancer cohort consortium (I4C)

Experimental evidence suggests that perinatal light imprinting of circadian clocks and systems may affect downstream physiology and cancer risk in later life. For humans, the predominant circadian stimulus is the daily light-dark cycle. Herein, we explore associations between perinatal photoperiod characteristics (photoperiod: duration of daylight as determined by time-of-year and location) and childhood cancer risk. We use pooled data on 182,856 mothers and babies from prospective birth cohorts in six countries (Australia, Denmark, Israel, Norway, UK, USA) within the International Childhood Cancer Cohort Consortium (I4C). Cox proportional hazards regression was used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). In line with predicted differential dose-responses, restricted cubic splines indicate a potential non-linear, non-monotonic relationship between perinatal mean daily photoperiod (0-24 h) and childhood cancer risk. In a restricted analysis of 154,121 individuals who experienced third trimester photoperiods exclusively within the 8-16-h range, the relative risk of developing childhood cancer decreased by 9% with every hour increase in third trimester mean daily photoperiod [HR: 0.91 (95%CIs: 0.84-0.99)]. In conclusion, in this first study of perinatal photoperiod and childhood cancer, we detected an inverse ["protective"] linear association between third trimester mean daily photoperiod and childhood cancer risk in the 8-16-h set of the total study population. Limited statistical power impeded the investigation of risks with individuals exposed to more extreme photoperiods. Future studies are needed to confirm differential photoperiod-associated risks and further investigations into the hypothesized circadian imprinting mechanism are warranted.

Birth seasonality of childhood central nervous system tumors: Analysis of primary data from 16 Southern-Eastern European population-based registries

Season of birth, a surrogate of seasonal variation of environmental exposures, has been associated with increased risk of several cancers. In the context of a Southern-Eastern Europe (SEE) consortium, we explored the potential association of birth seasonality with childhood (0-14 years) central nervous system (CNS) tumors. Primary CNS tumor cases (n = 6,014) were retrieved from 16 population-based SEE registries (1983-2015). Poisson regression and meta-analyses on birth season were performed in nine countries with available live birth data (n = 4,987). Subanalyses by birth month, age, gender and principal histology were also conducted. Children born during winter were at a slightly increased risk of developing a CNS tumor overall [incidence rate ratio (IRR): 1.06, 95% confidence intervals (CI): 0.99-1.14], and of embryonal histology specifically (IRR: 1.13, 95% CI: 1.01-1.27). The winter peak of embryonal tumors was higher among boys (IRR: 1.24, 95% CI: 1.05-1.46), especially during the first 4 years of life (IRR: 1.33, 95% CI: 1.03-1.71). In contrast, boys <5 years born during summer seemed to be at a lower risk of embryonal tumors (IRR: 0.73, 95% CI: 0.54-0.99). A clustering of astrocytomas was also found among girls (0-14 years) born during spring (IRR: 1.23, 95% CI: 1.03-1.46). Although the present exploratory results are by no means definitive, they provide some indications for age-, gender- and histology-related seasonal variations of CNS tumors. Expansion of registration and linkage with cytogenetic reports could refine if birth seasonality is causally associated with CNS tumors and shed light into the complex pathophysiology of this lethal disease.

Seasonality in Pediatric Cancer

Although seasonal trends in incidence and diagnosis of pediatric cancers have been widely investigated, the results have been inconclusive. A consistent seasonal trend may possibly provide etiological insights into pediatric cancers. This study aims to determine if there is a seasonal variation in cancer diagnoses in the pediatric population at the IWK Health Centre, a tertiary care center serving three Canadian provinces: Nova Scotia, New Brunswick, and Prince Edward Island. All pediatric cancer patients aged 0-20 y diagnosed from 1995 to 2015 at the center were included in this study. The annual data was divided into four seasonal periods (December to February, March to May, June to August, and September to November). The cancer diagnoses were categorized as leukemia, lymphoma, sarcoma, brain tumors, and miscellaneous. Seasonal variation was assessed by a harmonic function in a Poisson regression model. The amplitude of multiplicative change in the incidence rate caused by the seasonal variation is expressed as the incidence rate ratio (IRR). For all cancer diagnoses for the entire cohort of 1200 patients, the IRR was 1.03 [95% confidence interval (CI) 0.96-1.13]. None of the IRRs for the cancer groups indicated a statistically significant seasonality of cancer diagnosis: Leukemia 1.11 (95% CI 0.96-1.28); Lymphoma 1.17 (95% CI 0.93-1.47); Sarcoma 1.29 (95% CI 0.99-1.69); Brain tumors 1.16 (95% CI 0.97-1.38); Miscellaneous 1.09 (95% CI 0.93-1.27). The present study did not show a seasonal variation in the various cancer types in the pediatric population at the IWK.

Perinatal light imprinting of circadian clocks and systems (PLICCS): A signature of photoperiod around birth on circadian system stability and association with cancer

Recent findings from animal models suggest that plasticity of human circadian clocks and systems may be differentially affected by different paradigms of perinatal photoperiod exposure to the detriment of health in later life, including cancer development. Focusing on the example of cancer, we carry out a series of systematic literature reviews concerning perinatal light imprinting of circadian clocks and systems (PLICCS) in animal models, and concerning the risk of cancer development with the primary determinants of the perinatal photoperiod, namely season of birth or latitude of birth. The results from these systematic reviews provide supporting evidence of the PLICCS and cancer rationale and highlight that investigations of PLICCS in humans are warranted. Overall, we discuss findings from experimental research and insights from epidemiological studies. Considerations as to how to "test" PLICCS in epidemiological studies and as to the potential for non-invasive preventative measures during perinatal periods close our synthesis. If the PLICCS rationale holds true, it opens the exciting prospect for amenable, early-life, preventative measures against cancer development (and other disorders) in later life. Indeed, non-invasive anthropogenic light exposure may have enormous potential to alleviate the public health and economic burden of circadian-related diseases.

Central nervous system tumors: a single center pathology review of 34,140 cases over 60 years

BACKGROUND

Tumor epidemiology is a significant part of CNS (central nervous system) tumor studies. Reassessment of original sections can update our knowledge of tumor spectrum. Here, we discuss the features of CNS tumor pathology in a single center.

METHODS

A total of 34140 cases from 1950 to 2009 were collected; sections from 1990 to 2009 were reassessed according to WHO 2007 classification, and cases from 1950 to 1989 were classified according to the previous pathological diagnosis.

RESULTS

Seven CNS tumor categories during 1990 to 2009 were as follow: neuroepithelial tissue (38.0%), tumors of the meninges (36.5%), tumors of the sellar region (4.1%), germ cell tumors (1.3%), tumors of cranial and paraspinal nerves (13.3%), lymphomas and hematopoietic neoplasm (1.7%), metastatic tumors (5.1%), where histological types by age and sex were diverse. Overall, males exceeded females in distributions of most CNS tumor subtypes, while tumors of the meninges occurred more frequently in females. The case number of lymphomas and hematopoietic neoplasms grew the fastest during the past five years, and the distribution of neuroepithelial tumors remained stable over the past twenty years.

CONCLUSIONS

Despite the possibilities of cross sample biases, the data in this series could suggest a similar CNS tumor spectrum as might occur in other developing countries.

Space-time clustering of childhood central nervous system tumours in Yorkshire, UK

BACKGROUND

We specifically tested the aetiological hypothesis that a factor influencing geographical or temporal heterogeneity of childhood central nervous system (CNS) tumour incidence was related to exposure to a transient environmental agent.

METHODS

Information was extracted on individuals aged 0-14 years, diagnosed with a CNS tumour between the 1st January 1974 and 31st December 2006 from the Yorkshire Specialist Register of Cancer in Children and Young People. Ordnance Survey eight-digit grid references were allocated to each case with respect to addresses at the time of birth and the time of diagnosis, locating each address to within 0.1 km. The following diagnostic groups were specified a priori for analysis: ependymoma; astrocytoma; primitive neuroectodermal tumours (PNETs); other gliomas; total CNS tumours. We applied the K-function method for testing global space-time clustering using fixed geographical distance thresholds. Tests were repeated using variable nearest neighbour (NN) thresholds.

RESULTS

There was statistically significant global space-time clustering for PNETs only, based on time and place of diagnosis (P = 0.03 and 0.01 using the fixed geographical distance and the variable NN threshold versions of the K-function method respectively).

CONCLUSIONS

There was some evidence for a transient environmental component to the aetiology of PNETs. However, a possible role for chance cannot be excluded.

Influence of photoperiod on hormones, behavior, and immune function

Photoperiodism is the ability of plants and animals to measure environmental day length to ascertain time of year. Central to the evolution of photoperiodism in animals is the adaptive distribution of energetically challenging activities across the year to optimize reproductive fitness while balancing the energetic tradeoffs necessary for seasonally-appropriate survival strategies. The ability to accurately predict future events requires endogenous mechanisms to permit physiological anticipation of annual conditions. Day length provides a virtually noise free environmental signal to monitor and accurately predict time of the year. In mammals, melatonin provides the hormonal signal transducing day length. Duration of pineal melatonin is inversely related to day length and its secretion drives enduring changes in many physiological systems, including the HPA, HPG, and brain-gut axes, the autonomic nervous system, and the immune system. Thus, melatonin is the fulcrum mediating redistribution of energetic investment among physiological processes to maximize fitness and survival.