The burden of cancer attributable to modifiable risk factors in Canada: Methods overview

Up-to-date estimates of current and projected future cancer burden attributable to various exposures are essential for planning and implementing cancer prevention initiatives. The Canadian Population Attributable Risk of Cancer (ComPARe) study was conducted to: i) estimate the number and proportion of cancers diagnosed among adults in Canada in 2015 that are attributable to modifiable risk factors and ii) project the future avoidable cancers by 2042 under various intervention targets. We estimated the population attributable risk (with 95% confidence intervals) and the potential impact fraction of cancers associated with selected lifestyle, environmental, and infectious factors. Exposure-specific sensitivity analyses were also completed where appropriate. Several exposures of interest included active and passive smoking, obesity and abdominal adiposity, leisure-time physical inactivity, sedentary behaviour, alcohol consumption, insufficient fruit and vegetable intake, red and processed meat consumption, air pollution (PM2.5, NO₂), indoor radon gas, ultraviolet radiation (UVR), hepatitis B and C virus, Helicobacter pylori, Epstein-Barr virus, human papillomavirus, human herpesvirus type 8 and human T-cell lymphotropic virus type 1. We used the 2015 cancer incidence data for 35 cancer sites from the Canadian Cancer Registry and projected cancer incidence to 2042 using historical data from 1983 to 2012. Here, we provide an overview of the data sources and methods used in estimating the current and future cancer burden in Canada. Specific methodologic details for each exposure are included in the individual articles included as part of this special issue.

Estimating the current and future cancer burden in Canada: methodological framework of the Canadian population attributable risk of cancer (ComPARe) study

INTRODUCTION

The Canadian Population Attributable Risk of Cancer project aims to quantify the number and proportion of cancer cases incident in Canada, now and projected to 2042, that could be prevented through changes in the prevalence of modifiable exposures associated with cancer. The broad risk factor categories of interest include tobacco, diet, energy imbalance, infectious diseases, hormonal therapies and environmental factors such as air pollution and residential radon.

METHODS AND ANALYSIS

Using a national network, we will use population-attributable risks (PAR) and potential impact fractions (PIF) to model both attributable (current) and avoidable (future) cancers. The latency periods and the temporal relationships between exposures and cancer diagnoses will be accounted for in the analyses. For PAR estimates, historical exposure prevalence data and the most recent provincial and national cancer incidence data will be used. For PIF estimates, we will model alternative or 'counterfactual' distributions of cancer risk factor exposures to assess how cancer incidence could be reduced under different scenarios of population exposure, projecting incidence to 2042.

DISSEMINATION

The framework provided can be readily extended and applied to other populations or jurisdictions outside of Canada. An embedded knowledge translation and exchange component of this study with our Canadian Cancer Society partners will ensure that these findings are translated to cancer programmes and policies aimed at population-based cancer risk reduction strategies.

An update to the recommended core content for sun safety messages for public education in Canada: A consensus report

Reducing ultraviolet radiation exposure decreases the risk of skin cancer and eye damage. Between 1996 and 2006, Canadians increased their time in the sun without improving protection. National consensus on sun protection information for the public was last achieved in 1994. Public messages have since been modified inconsistently. The Ontario Sun Safety Working Group initiated a review of messages and engaged a scientific panel to draft message content. Working Group members then delivered a national consensus process, engaging a National Steering Committee, a health communications expert and representatives from 28 organizations through a workshop with pre- and post-workshop surveys. The result of the consensus process is the updated Recommended Core Content for Sun Safety Messages in Canada. Four groups of statements comprise the new content: Key Facts, Primary Recommended Protective Action Statements, Additional Recommended Protective Action Statements, and Tips for Implementing the Primary Protective Actions. Organizations are encouraged to adopt, at minimum, the Primary Recommended Protective Action Statements as the basis for public messaging. The recommended core content establishes a common understanding of what is needed for effective sun protection. The underlying expectation is that, as a key next step, content will be tailored for different subpopulations and health promotion campaigns.

Induction of apoptosis and reduction of MMP gene expression in the U373 cell line by polyphenolics in Aronia melanocarpa and by curcumin

Malignant brain tumours are rare but are the most challenging types of cancers to treat. Despite conventional multimodality approaches available for their management, the outlook for most patients remains dismal due to the ability of the tumour cells to invade the normal brain. Attention has now focused on novel therapeutic interventions such as as the use of micronutrients. Both chokeberry extract (Aronia melanocarpa), which is rich in natural pigments such as anthocyanins and curcumin (diferuloylmethane) found in turmeric (Curcuma longa) have been reported to possess anticancer properties in other cancers. The aim of this study was to extend our previous research to evaluate the therapeutic potential of these two agents by testing their ability to induce apoptosis in an established glioblastoma cell line (U373). This was accomplished by treating the cells for 48 h with either chokeberry extract or curcumin, and using the Annexin-V assay. Gene profiles of 8 MMPs (2, 9, 14, 15, 16, 17, 24 and 25) and 4 TIMPs (1, 2, 3 and 4) were analysed for effects of mediators of invasion by quantitative real-time polymerase chain reaction (RT-PCR). The IC50 values determined for curcumin and chokeberry extract were 15 and 200 µg/ml, respectively. Our results also suggest that curcumin induces apoptosis but chokeberry extract is necrotic to this cell line. It is possible that chokeberry extract kills the cells by other non-apoptotic pathways. In addition, the RT-PCR results show downregulation of the gene expression of MMP-2, -14, -16 and -17 for both micronutrients. Taken together, the comparative data suggest that both curcumin and chokeberry extract may exhibit their anticancer potential by inducing apoptosis and inhibiting invasion by reducing MMP gene expression.

BMI, diet and female reproductive factors as risks for thyroid cancer: a systematic review

Background

Thyroid cancer incidence rates have been increasing worldwide but the reason behind this is unclear. Both the increasing use of diagnostic technologies allowing the detection of thyroid cancer and a true increase in thyroid cancer incidence have been proposed. This review assesses the role of body mass index (BMI), diet, and reproductive factors on the thyroid cancer trend.

Methods

Epidemiologic studies of the selected risk factors up to June 2010 were reviewed and critically assessed.

Results

Among the thirty-seven studies reviewed and despite variation in the risk estimates, most papers supported a small but positive association for BMI (risk estimate range: 1.1–2.3 in males and 1.0–7.4 in females.). Among specific dietary components, there was no consistent association of thyroid cancer risk with iodine intake through fortification (risk estimate range: 0.49–1.6) or fish consumption (risk estimate range 0.6–2.2), nor with diets high in cruciferous vegetables (risk estimate range 0.6–1.9). A small number of studies showed a consistent protective effect of diets high in non-cruciferous vegetable (risk estimate range: 0.71–0.92). Among reproductive factors (pregnancy, parity, number of live births, use of prescription hormones, menstrual cycle regularity, and menopausal status), none were consistently associated with higher thyroid cancer risk.

Conclusions

BMI had the strongest link to thyroid cancer risk among those examined. Detailed examinations of population-level risk factors can help identify and support prevention efforts to reduce the burden of thyroid cancer.

Direct determination of the positions of the deuterium atoms of the bound water in -concanavalin A by neutron Laue crystallography

The correct positions of the deuterium (D) atoms of many of the bound waters in the protein concanavalin A are revealed by neutron Laue diffraction. The approach includes cases where these water D atoms show enough mobility to render them invisible even to ultra-high resolution synchrotron-radiation X-ray crystallography. The positions of the bound water H atoms calculated on the basis of chemical and energetic considerations are often incorrect. The D-atom positions for the water molecules in the Mn-, Ca- and sugar-binding sites of concanavalin A are described in detail.

Personal history of childhood abuse among clinicians

We conducted a survey to determine the prevalence, characteristics, and effects of a history of childhood sexual and physical abuse among professionals responsible for evaluating child sexual abuse allegations. A gender-stratified random sample of 1,635 United States clinicians was drawn from the most current national directories of clinical social work, pediatrics, psychiatry, and psychology. We received 656 completed questionnaires, yielding a 42% response rate. Thirteen percent of the men and 20% of the women reported a personal history of childhood sexual abuse; 7.3% of the men and 6.9% of the women reported a history of physical abuse as children. The modal age at which both genders were sexually abused was 8 years. The modal age at the time of physical abuse was 10 years for both sexes. Of those sexually abused, 50% of both genders were sexually abused for only 1 year. Of those physically abused, more than 50% of both genders were physically abused for 3 or more years. Older females were more likely to report a history of sexual abuse than were their younger cohorts. In this population, physical abuse was overwhelmingly perpetrated by parents. However, the modal perpetrators of sexual abuse (for both females and males) were male acquaintances or male strangers. Fathers and stepfathers were unlikely to be perpetrators of sexual abuse (3% for males and 12% for females) in this sample. For both genders, particularly males, sexually abused respondents were less likely to be married than their nonabused cohorts. Both men and women who had been sexually abused were more likely to be in nonmarital relationships than were those who had not been sexually abused. Women who had been sexually abused were less likely to have raised children than were women who had not been sexually abused. Respondents who had been sexually abused and/or physically abused were more likely to believe allegations of sexual abuse contained in 16 vignettes alleging sexual abuse.

Clinician responses to sexual abuse allegations

We conducted a survey using an experimental design to identify how and to what extent specific personal and case factors affect clinicians' judgments about sexual abuse allegations. We drew a stratified random sample of 1,635 United States clinicians from national directories of clinical social work, pediatrics, psychiatry and psychology. Six hundred and fifty-six completed questionnaires were obtained, yielding a 42% response rate. We asked each subject to read and rate, on a 6 point scale, 16 vignettes alleging sexual abuse. The scale ranged from 1 (very confident it did not occur), to 6 (very confident it did occur). On average, respondents were "slightly confident sexual abuse had occurred" (M = 4.03; SD = 0.6). This finding was significantly different from a mean of 3.50, which is the expected null result. Seven case factors affected credibility ratings at the .01 level; perpetrators' race (Caucasians viewed as perpetrators more than minorities); perpetrators' relationship to victim (family members more often seen as perpetrators); victims' race (minorities more credible as victims); victims' affect (those showing negative affect more believable); age (younger victims more often seen as victimized); behavioral changes in the victim; and perpetrator's history of substance abuse. Six clinician factors were significant at the .05 level: age (younger clinicians were more credulous), gender (females more credulous), discipline (clinical social workers more credulous), theoretical orientation (family systems oriented more credulous) and personal history of sexual or physical abuse (abuse history more credulous).