Trevor J B Dummer’s research while affiliated with University of British Columbia and other places

Cancer is rapidly increasing worldwide and urgent global action towards cancer control is required. Consistent with global trends, Canada is expected to experience a near doubling in new cases and cancer deaths between 2020–2040; population growth and ageing being the primary drivers. The projected increased cancer incidence and its associated costs is expected to further exacerbate socioeconomic inequities. Focused actions to prevent cancer, to detect it earlier when more treatable, and, to lower the risk of recurrence, must be prioritized. Almost half of all cancers are preventable, caused by risk factors that are potentially avoidable and modifiable. Integrating cancer prevention with care-based models is necessary and represents the most cost-effective and sustainable approach to control cancer. To be effective, prevention efforts must consider the cancers impacting local populations and understand how community and individual factors interact within the spatial and temporal contexts in which people live. This study is part of the Nova Scotia Community Cancer Matrix project which profiles the cancers impacting communities over time; measuring associations between cancer and socioeconomic status (SES); and determining how the joint spatial distribution of cancers can be used to address inequities, identify priority populations and strengthen prevention efforts. Using Bayesian inference to model spatio-temporal variations in 58,206 cases diagnosed in 301 communities between 2001–2017, across 10 preventable cancer types, we report significant disparities in cancer risk across communities based on sex and community SES. The work highlights the utility of small-area mapping to identify at-risk communities and understand how community-SES impacts risk. It also uncovers significant inequities rooted in the differential distribution of material and social capacity, operating beyond the control of individuals. The approach is implementable to other regions to inform and strengthen prevention efforts aiming at reducing the burden of cancer or that of other diseases.

Breast cancer is a significant global health concern, with millions of cases diagnosed annually. Risk factors for breast cancer include obesity, physical inactivity, poor diet, and alcohol use. Urbanization introduces exposures such as traffic-related air pollution (TRAP), which may impact breast cancer risk. To assess the impact of TRAP, measured in this study using nitrogen dioxide (NO2), on the risk of post-menopausal breast cancer we conducted a secondary analysis of baseline and follow-up data from the Alberta Tomorrow Project (ATP) cohort, linked to geographic data at the postal code level from the Canadian Urban Environmental Health Research Consortium (CANUE). Cox proportional hazard regression models were built to assess the association between breast cancer risk and NO2. Direct acyclic graphs (DAG) were used to identify and select relevant confounders for adjustment. The study included 15,536 post-menopausal women and 523 incident breast cancer cases over 12.6 years of follow-up. The hazard ratio (HR) for the initial model, which included all potential confounders (age, education, number of births, fruits and vegetables consumption, income, physical activity, BMI, and smoking) was 1.01 per 10-ppb increase in NO2. The adjusted HR for a 10-ppb increase in NO2 measured at baseline (the year participants completed the health and behaviours survey) was 1.10 (95% CI = 0.90, 1.34). Our study found no significant association between NO2 exposure and post-menopausal breast cancer risk. The variation in reported hazard ratios (HRs) — ranging from 1.01 to 1.10 — reflects different models adjusting for different variables. Our findings suggest a risk magnitude similar to other studies, yet the lack of significant association may be due to sample size limitations and lower NO2 levels in Alberta compared to other regions globally. Supplementary Information The online version contains supplementary material available at 10.1038/s41598-025-04373-x.

Background Breast cancer is the most commonly diagnosed cancer among women in Canada. Screening is effective in reducing breast cancer mortality through early cancer detection. However, data on individual social and medical characteristics contributing to variation in adherence to screening is limited. Methods Using multivariable logistic regression, we analyzed self‐reported questions on engagement in screening mammography from five regions of the Canadian Partnership for Tomorrow's Health (CanPath), including the BC Generations Project (BCGP), Alberta's Tomorrow Project (ATP), the Ontario Health Study (OHS), Quebec's CARTaGENE, and the Atlantic Partnership for Tomorrow's Health Study (Atlantic PATH). Results The study population included 79,986 and 46,907 individuals aged 50–74 and 40–49 years at study enrollment, respectively. Most participants self‐reported undergoing screening mammography less than 2 years from study enrollment, ranging from 77.8% in OHS to 86.3% in BCGP. Factors significantly associated with a lower odd of ever undergoing screening mammography were lower household income, being single/never married, current daily smoking, poor self‐perceived health, no history of breast feeding, and ≥ 24 months since last routine medical check‐up by a doctor or nurse. Among women aged 40–49 years with a first‐degree family history of breast cancer (N = 4212 [8.9%]), the likelihood of ever being screened varied by region and was significantly lower among individuals with post menopause and more than 12 months since last medical check‐up. Conclusion Factors associated with screening adherence that were identified in this study namely household income, self‐perceived health, and routine medical check‐ups should be considered as potential factors for targeting undeserved communities and increasing engagement in screening at both provincial and national levels. The observed variation in mammography among women aged 40 to 49 years with family history of breast cancer, may inform the current guidelines for potential benefits of early screening initiation.

Objectives Long-term exposure to air pollution has been associated with higher risk of cardiovascular mortality. Less is known about the association of air pollution with initial development of cardiovascular disease. Herein, the association between low-level exposure to air pollutants and subclinical carotid atherosclerosis in adults without known clinical cardiovascular disease was investigated. Design Cross-sectional analysis within a prospective cohort study. Setting The Canadian Alliance for Healthy Hearts and Minds Cohort Study; a pan-Canadian cohort of cohorts. Participants Canadian adults (n = 6645) recruited between 2014–2018 from the provinces of British Columbia, Alberta, Ontario, Quebec, and Nova Scotia, were studied, for whom averages of exposures to nitrogen dioxide (NO2), ozone (O3), and fine particulate matter (PM2.5) were estimated for the years 2008–2012. Main outcome measure Carotid vessel wall volume (CWV) measured by magnetic resonance imaging (MRI). Results In adjusted linear mixed models, PM2.5 was not consistently associated with CWV (per 5 μg/m³ PM2.5; adjusted estimate = -8.4 mm³; 95% Confidence Intervals (CI) -23.3 to 6.48; p = 0.27). A 5 ppb higher NO2 concentration was associated with 11.8 mm³ lower CWV (95% CI -16.2 to -7.31; p<0.0001). A 3 ppb increase in O3 was associated with 9.34 mm³ higher CWV (95% CI 4.75 to 13.92; p<0.0001). However, the coarse/insufficient O3 resolution (10 km) is a limitation. Conclusions In a cohort of healthy Canadian adults there was no consistent association between PM2.5 or NO2 and increased CWV as a measure of subclinical atherosclerosis by MRI. The reasons for these inconsistent associations warrant further study.

Background Patterns of health services utilization among children with inflammatory bowel disease (IBD) are important to understand as the number of children with IBD continues to increase. We compared health services utilization and surgery among children diagnosed <10 years of age (Paris classification: A1a) and between 10 and <16 years of age (A1b). Methods Incident cases of IBD diagnosed <16 years of age were identified using validated algorithms from deterministically linked health administrative data in 5 Canadian provinces (Alberta, Manitoba, Nova Scotia, Ontario, Quebec) to conduct a retrospective cohort study. We compared the frequency of IBD-specific outpatient visits, emergency department visits, and hospitalizations across age groups (A1a vs A1b [reference]) using negative binomial regression. The risk of surgery was compared across age groups using Cox proportional hazards models. Models were adjusted for sex, rural/urban residence location, and mean neighborhood income quintile. Province-specific estimates were pooled using random-effects meta-analysis. Results Among the 1165 (65.7% Crohn’s) children with IBD included in our study, there were no age differences in the frequency of hospitalizations (rate ratio [RR], 0.88; 95% confidence interval [CI], 0.74-1.06) or outpatient visits (RR, 0.95; 95% CI, 0.78-1.16). A1a children had fewer emergency department visits (RR, 0.70; 95% CI, 0.50-0.97) and were less likely to require a Crohn’s-related surgery (hazard ratio, 0.49; 95% CI, 0.26-0.92). The risk of colectomy was similar among children with ulcerative colitis in both age groups (hazard ratio, 0.71; 95% CI, 0.49-1.01). Conclusions Patterns of health services utilization are generally similar when comparing children diagnosed across age groups.

Background Lung cancer is one of the most commonly diagnosed cancers and the leading cause of cancer-related death worldwide. Although smoking is the primary cause of the cancer, lung cancer is also commonly diagnosed in people who have never smoked. Currently, the proportion of people who have never smoked diagnosed with lung cancer is increasing. Despite this alarming trend, this population is ineligible for lung screening. With the increasing proportion of people who have never smoked among lung cancer cases, there is a pressing need to develop prediction models to identify high-risk people who have never smoked and include them in lung cancer screening programs. Thus, our systematic review is intended to provide a comprehensive summary of the evidence on existing risk prediction models for lung cancer in people who have never smoked. Methods Electronic searches will be conducted in MEDLINE (Ovid), Embase (Ovid), Web of Science Core Collection (Clarivate Analytics), Scopus, and Europe PMC and Open-Access Theses and Dissertations databases. Two reviewers will independently perform title and abstract screening, full-text review, and data extraction using the Covidence review platform. Data extraction will be performed based on the Checklist for Critical Appraisal and Data Extraction for Systematic Reviews of Prediction Modeling Studies (CHARMS). The risk of bias will be evaluated independently by two reviewers using the Prediction model Risk-of-Bias Assessment Tool (PROBAST) tool. If a sufficient number of studies are identified to have externally validated the same prediction model, we will combine model performance measures to evaluate the model’s average predictive accuracy (e.g., calibration, discrimination) across diverse settings and populations and explore sources of heterogeneity. Discussion The results of the review will identify risk prediction models for lung cancer in people who have never smoked. These will be useful for researchers planning to develop novel prediction models, and for clinical practitioners and policy makers seeking guidance for clinical decision-making and the formulation of future lung cancer screening strategies for people who have never smoked. Systematic review registration This protocol has been registered in PROSPERO under the registration number CRD42023483824.

Purpose The incidence of childhood-onset inflammatory bowel disease (IBD) is rising. We described variation in health services utilization and need for surgery among children with IBD between six and 60 months following IBD diagnosis across Canadian pediatric centers and evaluated the associations between care provided at diagnosis at each center and the variation in these outcomes. Patients and Methods Using population-based deterministically-linked health administrative data from four Canadian provinces (Alberta, Manitoba, Nova Scotia, Ontario) we identified children diagnosed with IBD <16 years of age using validated algorithms. Children were assigned to a pediatric center of care using a hierarchical approach based on where they received their initial care. Outcomes included IBD-related hospitalizations, emergency department (ED) visits, and IBD-related abdominal surgery occurring between 6 and sixty months after diagnosis. Mixed-effects meta-analysis was used to pool results and examine the association between center-level care provision and outcomes. Results We identified 3784 incident cases of pediatric IBD, of whom 2937 (77.6%) were treated at pediatric centers. Almost a third (31.4%) of children had ≥1 IBD-related hospitalization and there were 0.66 hospitalizations per person during follow-up. More than half (55.8%) of children had ≥1 ED visit and there were 1.64 ED visits per person. Between-center heterogeneity was high for both outcomes; centers where more children visited the ED at diagnosis had more IBD-related hospitalizations and more ED visits during follow-up. Between-center heterogeneity was high for intestinal resection in Crohn’s disease but not colectomy in ulcerative colitis. Conclusion There is variation in health services utilization among children with IBD and risk of undergoing intestinal resection in those with Crohn’s disease, but not colectomy among children with ulcerative colitis, across Canadian pediatric tertiary-care centers. Improvements in clinical care pathways are needed to ensure all children have equitable and timely access to high quality care.

Introduction Visceral adiposity is emerging as a key driver of cardio-metabolic risk factors and cardiovascular disease (CVD), but its relationship with cardiac structure and function is not well characterized across sexes. Using the Canadian Alliance for Healthy Heart and Minds (CAHHM), a large population-based cohort study, we sought to determine the association of visceral adipose tissue (VAT) on subclinical left ventricular (LV) remodeling in males and females. Methods As part of the CAHHM study, 6522 participants free of clinical CVD (mean age: 57.4 [8.8 SD] years; 3,671 females, 56%) underwent magnetic resonance imaging (MRI) in which LV parameters and VAT volume were measured. Information about demographic factors, CV risk factors, and anthropometric measurements were obtained. Subclinical cardiac remodelling was defined as altered LV concentricity, represented by increased LV mass-to-volume ratio (LVMV). Results Males had a higher VAT volume (80.8 mL; 95% CI: 74.6 t 86.9) compared to females (64.7 mL; 95% CI: 58.5 to 70.8), adjusted for age and height. Among both males and females, VAT was significantly associated with subclinical cardiac remodeling (increased LVMV), independent of other CV risk factors. In multiple regression models adjusted for cardiovascular risk factors, age, and height, every 1 sex-specific standard deviation increase in VAT corresponded to an increase of 0.037 g/mL in LVMV (95% CI: 0.032 to 0.041; p<0.001), which was consistent across both sexes. Notably, a 1 standard deviation increase in VAT is associated with a LVMV that is 20 times higher than what is observed with natural aging alone (0.0020 g/mL rise in LVMV (95% CI 0.0016 to 0.0025), and 1.5 times higher than the impact of an integrated measure of CV risk factors (0.024 g/mL; 95% CI: 0.020 to 0.028). Conclusion VAT significantly influences subclinical cardiac remodeling in both males and females, independent of other cardiovascular risk factors and age. Further research to understand the pathways by which VAT contributes to accelerated cardiac aging is needed.