Childhood cancer in the Northern Region, 1968-82: incidence in small geographical areas.

The place of residence of all cases of childhood cancer occurring in the Northern Region from 1968 to 1982 has been analysed by electoral wards. The wards have been ranked according to rate and Poisson probability. Both rankings show a wide geographical scatter throughout the region of areas with an apparent excess incidence of cancer. These areas are not confined to the Cumbrian coast.     

Cause-specific hospital admission and mortality among working men: association with socioeconomic circumstances in childhood and adult life, and the mediating role of daily stress

BACKGROUND: The aim of this study was to investigate the association of childhood and adulthood social class with the occurrence of specific diseases, including those not associated with a high mortality rate, and to investigate daily stress as the mechanism for that part of any association which cannot be accounted for by established risk factors. METHODS: This was a prospective cohort study with 25 years of follow-up for cause-specific morbidity and mortality. A total of 5577 Scottish men were recruited from 27 workplaces in the West of Scotland. Childhood social class was determined from the occupation held by the individual's father, and adulthood social class from the individual's occupation at enrolment. Daily stress was measured at enrolment using the Reeder Stress Inventory. RESULTS: Health differentials were found for cardiovascular diseases, lung cancer, peptic ulcer, asthma, accidents and violence, alcohol-related diseases, and perhaps psychiatric illness. Adulthood circumstances were associated with the incidence of most diseases in adulthood, the exception being stroke, which was strongly associated with less privileged circumstances in childhood. Both childhood and adulthood circumstances contributed to the incidence of coronary heart disease. Daily stress did not underlie any of these associations once the influence of established risk factors had been taken into account. CONCLUSIONS: Socioeconomic circumstances in childhood and adulthood both contribute to health differentials in adulthood, the relative contributions depending upon the particular disease. Where known risk factors explained only part of the excess of a disease among individuals raised or living in less-privileged circumstances, there was no evidence to suggest that daily stress was the reason for the unexplained excess.     

International variations in the incidence of childhood lymphomas

The International Agency for Research on Cancer has coordinated a worldwide study of childhood cancer incidence, with data provided by contributors from over 50 countries. We present here the results on lymphomas from this study and other sources. Hodgkin's disease had a relatively high incidence in North Africa and West Asia and a low incidence throughout East Asia. In populations of predominantly European origin, the highest rates tended to be in warmer countries of lower latitude. In industrialised Western countries, the incidence increased steeply with age and was low in childhood compared with that in young adults whereas elsewhere the increase in incidence between childhood and adults aged 20-34 was much less marked. The age-distribution of Hodgkin's disease in childhood appears to be related to levels of socio-economic development but the total incidence seems to be determined more by ethnic and environmental factors. The highest incidence of Burkitt's lymphoma occurred in tropical Africa and Papua New Guinea. Elsewhere, Burkitt's lymphoma was rare, though the incidence was higher in Spain, North Africa and the Middle East than in other areas. In most Western countries, a third of all non-Hodgkin lymphomas may be Burkitt's. There was no consistent pattern in the incidence of other non-Hodgkin lymphomas except for a tendency towards higher rates around the Mediterranean and in some Latin American registries.     

International variations in the incidence of childhood lymphomas

Summary. The International Agency for Research on Cancer has coordinated a worldwide study of childhood cancer incidence, with data provided by contributors from over 50 countries. We present here the results on lymphomas from this study and other sources. Hodgkin's disease had a relatively high incidence in North Africa and West Asia and a low incidence throughout East Asia. In populations of predominantly European origin, the highest rates tended to be in warmer countries of lower latitude. In industrialised Western countries, the incidence increased steeply with age and was low in childhood compared with that in young adults whereas elsewhere the increase in incidence between childhood and adults aged 20–34 was much less marked. The age-distribution of Hodgkin's disease in childhood appears to be related to levels of socio-economic development but the total incidence seems to be determined more by ethnic and environmental factors. The highest incidence of Burkitt's lymphoma occurred in tropical Africa and Papua New Guinea. Elsewhere, Burkitt's lymphoma was rare, though the incidence was higher in Spain, North Africa and the Middle East than in other areas. In most Western countries, a third of all non-Hodgkin lymphomas may be Burkitt's. There was no consistent pattern in the incidence of other non-Hodgkin lymphomas except for a tendency towards higher rates around the Mediterranean and in some Latin American registries.     

Spatiotemporal incidence rate data analysis by nonparametric regression

To monitor the incidence rates of cancers, AIDS, cardiovascular diseases, and other chronic or infectious diseases, some global, national, and regional reporting systems have been built to collect/provide population‐based data about the disease incidence. Such databases usually report daily, monthly, or yearly disease incidence numbers at the city, county, state, or country level, and the disease incidence numbers collected at different places and different times are often correlated, with the ones closer in place or time being more correlated. The correlation reflects the impact of various confounding risk factors, such as weather, demographic factors, lifestyles, and other cultural and environmental factors. Because such impact is complicated and challenging to describe, the spatiotemporal (ST) correlation in the observed disease incidence data has complicated ST structure as well. Furthermore, the ST correlation is hidden in the observed data and cannot be observed directly. In the literature, there has been some discussion about ST data modeling. But, the existing methods either impose various restrictive assumptions on the ST correlation that are hard to justify, or ignore partially or entirely the ST correlation. This paper aims to develop a flexible and effective method for ST disease incidence data modeling, using nonparametric local smoothing methods. This method can properly accommodate the ST data correlation. Theoretical justifications and numerical studies show that it works well in practice.     

Childhood leukemia and socioeconomic status in Canada

BACKGROUND: Leukemia is one of the most common potentially fatal illnesses in children, and its causes are not well understood. Although socioeconomic status (SES) has been related to leukemia in some studies, this apparent association may be attributable to ascertainment or participation bias. This study was undertaken to determine whether there is a difference in incidence of childhood leukemia for different levels of SES, as measured by neighborhood income, in an unselected population case group. METHODS: All cases of childhood leukemia diagnosed in the years 1985-2001 were identified from population-based cancer registries in Canada. Postal codes for the place of residence at diagnosis were used to ascertain the census neighborhoods for cases. We constructed neighborhood-based income quintiles from census population data, and stratified the population at risk by sex and 5-year age groupings. Age-standardized incidence rates and 95% confidence intervals (CIs) were calculated. We used Poisson regression to compare incidence rate ratios (RRs) across income quintiles. RESULTS: A slightly lower relative risk of childhood leukemia was observed in the poorest quintile compared with the richest (RR = 0.87; 95% CI = 0.80-0.95). The lower risk in the poorest quintile was restricted to acute lymphoid leukemia (0.86; 0.78-0.95) and was strengthened slightly by restriction to urban areas (0.83; 0.74-0.93). CONCLUSIONS: This analysis suggests that high SES is a true risk factor for childhood leukemia and that inconsistent results from other studies may be related to differences in case ascertainment or study participation.     

Diabetes and cancer risk: oncologic considerations

Type 2 diabetes mellitus and malignant tumors are frequent diseases worldwide. The incidence of these two diseases is growing continuously and causes serious health care problem. Population based epidemiologic studies show that the coexistence of type 2 diabetes and malignant tumors is more frequent than expected by the age-corrected incidence and prevalence of each disease. Epidemiologic studies and meta-analyses show that type 2 diabetes increases the risk and tumor specific mortality of certain cancers. The overlapping risk factors of the diseases suggest a relationship between type 2 diabetes and malignant tumors, with a significant role of obesity as a major risk factor. In the pathophysiology of type 2 diabetes there are several biological processes, which may explain the higher cancer risk in type 2 diabetes. In vitro experiments, and in vivo animal studies show that the mitotic effect of hyperinsulinemia plays an important role in the relationship of cancer and type 2 diabetes mellitus. Recent studies show that the different treatment modalities, antidiabetic drugs and their combinations used for the treatment of type 2 diabetes can modify cancer risk. The majority of the data show that metformin therapy decreases, while insulin secretagog drugs slightly increase the risk of certain types of cancers in type 2 diabetes. Metformin can decrease cell proliferation and induce apoptosis in certain cancer cell lines. Endogenous and exogenous (therapy induced) hyperinsulinemia may be mitogenic and may increase the risk of cancer in type 2 diabetes. Human studies showed that the analogue insulin glargin increases the risk of certain cancers. As a result of conceptual weaknesses in study design, data collection, and statistical methods the results of these studies are questionable. According to present knowledge, obtaining and maintaining optimal metabolic target values with the appropriate choice of treatment modality is the aim of treatment in type 2 diabetes. Presently, study results showing elevated mitogenic potential with some antidiabetic treatment modalities are not taken into account, when considering the choice of antidiabetic treatment in type 2 diabetic patients. In the care of patients with increased cancer risk, oncologic considerations should be taken into account. Well designed, prospective, clinical studies would be necessary to demonstrate the possible correlation between treatment modalities of type 2 diabetes and change of cancer risk in type 2 diabetes mellitus.     

The role of dietary fiber in gastrointestinal disease

The most consistent benefit of consumption of adequate dietary fiber is regular laxation; this effect alone justifies inclusion of fiber in the diet, in view of the enormous expenditure on drugs for digestive diseases. Dietary fiber has proved effective in decreasing symptoms of diverticular disease, Crohn's disease, and hemorrhoids in a limited number of small clinical studies. Fiber may also reduce the incidence of gallstone formation. Fiber is currently being touted as protection against colon cancer. However, the epidemiological and experimental data do not provide convincing evidence that fiber alone is a major determinant of risk for colon cancer. Furthermore, the data from international comparisons indicating that fiber is protective against colon cancer can be used in a similar simplistic manner to suggest that fiber may be a risk factor for stomach cancer. This should not dissuade individuals from obtaining adequate fiber from a wide variety of foods but should caution them against consumption of excessive amounts of fiber from a single source or from dietary supplements.     

Current status and epidemiological research needs for achieving a better understanding of the consequences of the Chernobyl accident

Twenty years after the Chernobyl accident, there is no clearly demonstrated increase in the incidence of cancers in the most affected populations that can be attributed to radiation from the accident, except for the dramatic increase in thyroid cancer incidence among those exposed in childhood and adolescence. Increases in the incidence of cancers and other diseases have been reported in Belarus, the Russian Federation, and Ukraine, but much of the increase appears to be due to other factors, including improvements in diagnosis, reporting, and registration. Recent findings indicate a possible doubling of leukemia risk among Chernobyl liquidators and a small increase in the incidence of premenopausal breast cancer in the very most contaminated districts. Increased risks of cardiovascular diseases and cataracts have also been reported. These findings, however, need confirmation in well-designed analytical epidemiological studies with careful individual dose reconstruction. The absence of demonstrated increases in cancer risk--apart from thyroid cancer--is not the proof that no increase has in fact occurred. Based on the experience of atomic bomb survivors, and assuming that there is a linear, no-threshold dose-response relationship between exposure to ionizing radiation and the development of cancer in humans, a small increase in the relative risk of cancer is expected, even at the low to moderate doses received. Given the large number of individuals exposed, the absolute number of cancer cases caused could be substantial, particularly in the future. It is therefore essential to continue to use population registries to monitor trends in disease morbidity and mortality in the most contaminated areas, as well as among liquidators, in order to assess the public health impact of the accident. Studies of selected populations and diseases are also essential in order to study the real effect of the accident and compare it to predictions. Careful studies may in particular provide important information on the effect of exposure rate and exposure type in the low to medium dose range and on factors that may modify radiation effects. As such, they may have important consequences for the radiation protection of patients and of the general population in case of further nuclear emergencies.     

Potential bias due to prevalent diseases in prospective studies

In prospective studies, subjects found to have the disease under investigation at the initial screening examination are commonly excluded from analyses. However, the possibility of bias due to prevalent conditions other than the disease of interest is usually not considered. In the present study, an algebraic development enables analysis of the effects of inclusion and exclusion of subjects with certain prevalent conditions upon risk estimates. Hypothetical data are presented for which an association between a risk factor and an incident disease could become null or even reversed after removing subjects with certain prevalent diseases. Bias appears even when the only association present is between risk factor and total disease incidence. Data from the Honolulu Heart Study also have been used to illustrate this finding, examining the association between coronary heart disease (CHD) incidence and smoking. Decisions regarding the inclusion or exclusion of subjects with prevalent diseases requires prior knowledge of alteration of usual risk factors levels by individuals with these diseases. Simply removing all subjects with prevalent diseases might on the contrary create bias. Therefore, people with prevalent diseases should be screened for potential alteration of their risk factor levels as a result of the diseases. The situation becomes still more complex when several risk factors and prevalent diseases need to be considered at the same time as it happens in multivariate analyses. Because this situation represents a bias, and not confounding or effect modification, controlling for the effect of prevalent diseases is not appropriate.     

Excess cumulative incidence estimation for matched cohort survival studies

We suggest a regression approach to estimate the excess cumulative incidence function (CIF) when matched data are available. In a competing risk setting, we define the excess risk as the difference between the CIF in the exposed group and the background CIF observed in the unexposed group. We show that the excess risk can be estimated through an extended binomial regression model that actively uses the matched structure of the data, avoiding further estimation of both the exposed and the unexposed CIFs. The method naturally deals with two time scales, age and time since exposure and simplifies how to deal with the left truncation on the age time-scale. The model makes it easy to predict individual excess risk scenarios and allows for a direct interpretation of the covariate effects on the cumulative incidence scale. After introducing the model and some theory to justify the approach, we show via simulations that our model works well in practice. We conclude by applying the excess risk model to data from the ALiCCS study to investigate the excess risk of late events in childhood cancer survivors.     

Surveillance of occupational and work-related diseases between 1993 and 1996 in an engineering company

There are established reporting schemes for some occupational and work-related illnesses but these schemes may underestimate the true incidence of such diseases. Not all cases may be referred to a participating physician and access to adequate diagnostic facilities are not always available. Collecting data directly from occupational health departments may overcome some problems related to under-reporting as they have good access to the entire working population within their company. The aim of this paper is to report the results from such a reporting scheme operated by a large multi-national engineering company during the period 1993-96. All UK sites of Lucas Industries (later LucasVarity) participated. A report form was completed by the occupational health department of each participating site each month. The report form gave abbreviated details of each case of occupational and work-related disease occurring at that site during the previous month. Forms were posted to a central office where the data was collated and analyzed. The incidence of respiratory diseases was broadly similar or slightly higher to that reported from other schemes. Musculoskeletal diseases were by far the most common category of disease reported. During a four year period of reporting the incidence of occupational and work-related diseases decreased overall by approximately 75%. As the reported incidence of respiratory disease was comparable with or slightly higher than that from other schemes, it appears that reporting schemes such as this can provide useful and accurate data. Musculoskeletal diseases are the most common type of disease attributed to work and should probably receive greater attention. The decrease in incidence seen in LucasVarity over time may reflect increased emphasis given to health and safety issues within the company during the reporting period.     

A comparison of spatial clustering and cluster detection techniques for childhood leukemia incidence in Ohio, 1996 – 2003

Background  

Spatial cluster detection is an important tool in cancer surveillance to identify areas of elevated risk and to generate hypotheses about cancer etiology. There are many cluster detection methods used in spatial epidemiology to investigate suspicious groupings of cancer occurrences in regional count data and case-control data, where controls are sampled from the at-risk population. Numerous studies in the literature have focused on childhood leukemia because of its relatively large incidence among children compared with other malignant diseases and substantial public concern over elevated leukemia incidence. The main focus of this paper is an analysis of the spatial distribution of leukemia incidence among children from 0 to 14 years of age in Ohio from 1996–2003 using individual case data from the Ohio Cancer Incidence Surveillance System (OCISS).     

Toward health for all in the European region of the WHO. Survey of progress accomplished. II. Preliminary conditions: demographic and health status

A review of recent progress towards the regional targets set for health for all by the Member States of the European Region of WHO, as regards preliminary conditions for health, and for indicators of mortality, morbidity and disability. Life expectancy, infant and maternal mortality, and mortality from ischaemic heart disease and from traffic accidents show an improvement, as does the incidence of several infectious diseases, but the situation has worsened or stagnated as regards suicide and cancer, and there is a lack of information on disability and chronic morbidity. Despite some progress, the goal of equity in health is still very far from being attained.     

Does smoking kill workers or working kill smokers? OR The mutual relationship between smoking, occupation, and respiratory disease.

Evidence accumulated since 1964 appears to show that occupation, not cigarette smoking, may be the primary cause of lung disease, especially of cancer and chronic obstructive disease. Comparisons of groups of individuals who smoke more with those who smoke less actually serve to contrast groups with a high proportion of blue-collar workers exposed to toxic fumes and a low proportion of professionals, managers, and proprietors with groups having lower proportions of blue-collar workers and higher proportions of professionals, managers, and proprietors. Thus, many diseases associated with smoking actually may be of occupational origin. Indeed, more than a dozen recent investigations of lung cancer epidemics among industrial workers have failed to find smoking to be a major cause (in some, not even a contributing cause). This evidence is strengthened further by shifts in the incidence of lung cancer that follow in time shifts in industrial employment patterns. Yet a worker's past smoking habits seem to play a key role in decreasing compensation awards for injuries that actually may be due to occupational exposure rather than personal habits. Thus, the relationship between smoking, occupation, and disease needs serious clarification. Smoking appears to have been used to divert attention away from the effects of occupational and environmental exposures to toxic substances.     

Paternal occupational exposure to pesticides or herbicides as risk factors for cancer in children and young adults: a case-control study from the North of England

Researchers in numerous studies have suggested that preconception paternal occupational exposures to various substances, including pesticides and herbicides, may be involved in the etiology of childhood cancers. Using data from the Northern Region Young Persons' Malignant Disease Registry, the authors investigated whether paternal occupations likely to involve such exposures, as recorded at the time of a child's birth, were associated with children's cancer risk. The authors matched cases (n = 4,723), on sex and year of birth, to controls from 2 independent sources: (1) all other patients from the registry with a different cancer and (2) 100 cancer-free individuals per case from the Cumbrian Births Database. An inverse association existed, particularly in males, between lymphoid leukemia and paternal occupations with likely exposures to pesticides and/or herbicides. However, this was not significant after stratifying by residential status (urban versus rural). Results do not support a role for preconception paternal occupational exposures to pesticides or herbicides in the etiology of childhood cancer.     

A monitoring system for occupational cancer

INTRODUCTION: The Italian Occupation and Safety Act (d.lgs 626/94) provided for the establishment of a nationwide occupational cancer registry, under the National Institute for Occupational Health and Safety (ISPESL), with the aim of detecting cancer cases of occupational origin and estimating the influence of occupation in cancer causation. METHODS: Information on cancer cases, drawn from six Italian population-based cancer registries (CRs of Friuli Venezia Giulia Region, Genoa Town and Genoa Province, Macerata Town, Umbria Region, Varese Town, Veneto Region), and on a random sample of population controls selected in each CRs area were linked with data on subjects employed in private enterprises that have been available in electronic form since 1974 at the National Institute for Social Security (INPS). In this way, both for cases and controls, the occupational histories of past employment were collected. A population-based case-control study covering the period 1990-1998 was carried out with the aim of estimating occupational cancer risk in the private sector by site and economic category in each area. Since one of the major drawbacks of this approach is the difficulty in distinguishing true occupational hazards from incidental findings derived from multiple comparisons, an extensive research of occupational literature was carried out, independently of the study results, to compare our results with existing knowledge on occupational risks. RESULTS: Pooled analysis of the most recent incidence data based on 36,379 cases and 29,572 controls was performed; 34 "statistically significant" associations were found for 11 economic categories. Using our literature review, 10 associations were supported by more than 5 publishedpapers, 14 by a number of papers between 1 and 5, and 10 associations had not been previously reported. CONCLUSIONS: This system appears suitable for assessing existing occupational cancer risks and can eventually lead to detecting occupational hazards in many areas of Italy. The system can also provide a list of cases suitable for in-depth search for past occupational exposures.     

Validity of cigarette smoking habits in three epidemiologic studies in Utah

Utah has lower incidence and mortality for many smoking-related forms of cancer and heart disease. It is an important epidemiologic question to assess whether the population attributable risk associated with cigarette smoking in this low-risk population is biased from under-reporting because of societal pressures not to smoke. To answer this question, we compared reported cigarette use to serum cotinine values in three different epidemiologic study designs. Included in these analyses were data from men interviewed for a cross-sectional study of dietary intake and hormones, women interviewed as a part of a case-control study of cervical cancer, and men interviewed in conjunction with a cardiovascular disease and hypertension family follow-up study. Cross-sectional study participants reported accurate cigarette usage 93.8% of the time; case-control participants accurately reported cigarette use 98.5% of the time; participants interviewed in the family cohort study correctly reported usage 82.8% of the time. Most inaccurate reporting of smoking was by exsmokers being followed for a disease known to be linked to smoking. The low attributable risk of smoking related to diseases in Utah is not from underreporting of cigarette smoking, and makes Utah an ideal population to examine other risk factors for diseases where smoking increases risk.