A cohort study of the multipollutant effects of PM2.5, NO2, and O3 on C-reactive protein levels during pregnancy.

Background: PM2.5, NO2, and O3 contribute to the development of adverse pregnancy complications. While studies have investigated the independent effects of these exposures, literature on their combined effects is limited. Our objective was to study the multipollutant effects of PM2.5, NO2, and O3 on maternal systemic C-reactive protein (CRP) levels. Methods: We used data from 1170 pregnant women enrolled in the Maternal-Infant Research on Environmental Chemicals Study (MIREC) study in Canada. Air pollution exposures were assigned to each participant based on residential location. CRP was measured in third-trimester blood samples. We fit multipollutant linear regression models and evaluated the effects of air pollutant mixtures (14-day averages) using repeated-holdout Weighted Quantile Sum (WQS) regression and by calculating the Air Quality Health Index (AQHI). Results: In multipollutant models adjusting for NO2, O3, and green space, each interquartile range (IQR) increase in 14-day average PM2.5 (IQR: 6.9 µg/m3) was associated with 27.1% (95% confidence interval [CI] = 6.2, 50.7) higher CRP. In air pollution mixture models adjusting for green space, each IQR increase in AQHI was associated with 37.7% (95% CI = 13.9, 66.5) higher CRP; and an IQR increase in the WQS index was associated with 78.6% (95% CI = 29.7, 146.0) higher CRP. Conclusion: PM2.5 has the strongest relationship of the individual pollutants examined with maternal blood CRP concentrations. Mixtures incorporating all three pollutants, assessed using the AQHI and WQS index, showed stronger relationships with CRP compared with individual pollutants and illustrate the importance of conducting multipollutant analyses.

Health effects of green prescription: A systematic review of randomized controlled trials.

An increasing number of studies have examined the effects of green prescription on various health outcomes. The aim of this study was to systematically review published randomized controlled trial studies on the health benefits of green prescriptions. We searched PubMed, Scopus, and Web of Science for the relevant original articles published in English until June 30, 2023. Our search initially retrieved 26176 articles, of which 31 studies were included in our review after removing the duplicates and excluding ineligible articles based on their titles, abstracts, and full-text review. Consistent positive health benefits of green prescription were reported for psychological health and wellbeing (16 out of 24 studies), cardiometabolic health (five out of nine studies), physical activity (eight out of nine studies), and inflammation (two out of two studies). The reviewed studies did not report any significant benefits in orthopedic conditions, pain, and recovery from exhaustion disorder due to their implemented green prescriptions; however, the number of studies was too small to generalize the effect of green prescriptions on these outcomes. The quality of these studies was generally acceptable, with 28 studies having some concerns regarding their overall risk of bias and only three studies with a high risk of bias. All in all, this systematic review suggests that green prescriptions can be effective in improving various health outcomes, but further studies with larger sample sizes and objective measures are needed.

External Validation of the FLIPI Risk Score Measured at Diagnosis and POD24 Among Individuals With Follicular Lymphoma at the Time of Subsequent Relapse.

BACKGROUND: The Follicular lymphoma international prognostic index (FLIPI) risk score and POD24 have previously been shown to have prognostic value in follicular lymphoma (FL), but the extent to which they can inform prognosis at the time of subsequent relapse is uncertain. PATIENTS AND METHODS: We conducted a longitudinal cohort study of individuals diagnosed with FL between 2004 and 2010 in Alberta, Canada who received front-line therapy and subsequently relapsed. FLIPI covariates were measured prior to the initiation of front-line therapy. Median overall survival (OS), progression-free survival (PFS2), and time to next treatment (TTNT2) were estimated from the time of relapse. RESULTS: A total of 216 individuals were included. The FLIPI risk score was highly prognostic at the time of relapse for OS (c-statistic = 0.70; HR[High vs. Low] = 7.38; 95% CI: 3.05-17.88), PFS2 (c-statistic = 0.68; HR[High vs. Low] = 5.84; 95% CI: 2.93-11.62) and TTNT2 (c-statistic = 0.68; HR[High vs. Low] = 5.72; 95% CI: 2.87-11.41). POD24 was not prognostic at the time of relapse for either OS, PFS2, or TTNT2 (c-statistic = 0.55). CONCLUSION: The FLIPI score measured at diagnosis may help with the risk stratification of individuals with relapsed FL.

Understanding Real-World Treatment Patterns and Clinical Outcomes among Metastatic Melanoma Patients in Alberta, Canada.

Immunotherapy and targeted therapies have been shown to considerably improve long-term survival outcomes in metastatic melanoma patients. Real-world evidence on the uptake of novel therapies and outcomes for this patient population in Canada are limited. We conducted a population-based retrospective cohort study of all metastatic melanoma patients diagnosed in Alberta, Canada (2015-2018) using electronic medical records and administrative data. Information on BRAF testing for patients diagnosed in 2017 or 2018 was obtained through chart abstraction. In total, 434 metastatic melanoma patients were included, of which 110 (25.3%) were de novo metastatic cases. The median age at diagnosis was 66 years (IQR: 57-76) and 70.0% were men. BRAF testing was completed for the majority of patients (88.7%). Among all patients, 60.4%, 19.1%, and 6.0% initiated first-line, second-line, and third-line systemic therapy. The most common therapies were anti-PD-1 and targeted therapies. The two-year survival probability from first-line therapy, second-line therapy, and third-line therapy was 0.50 (95% CI: 0.44-0.57), 0.26 (95% CI: 0.17-0.40), and 0.14 (95% CI: 0.40-0.46), respectively. In the first-line setting, survival was highest for patients that received ipilimumab or ipilimumab plus nivolumab, while targeted therapy had the highest survival in the second-line setting. This study indicates that novel therapies improve survival in the real world but a considerable proportion of patients do not receive treatment with systemic therapy.

Performance of the fecal immunochemical test for colorectal cancer and advanced neoplasia in individuals under age 50.

The increased demand for colonoscopy combined with increased incidence of colorectal cancer (CRC) among younger populations presents a need to determine FIT performance among individuals in this age group. We conducted a systematic review to assess test performance characteristics of FIT in detecting CRC and advanced neoplasia in younger age populations. A search through December 2022 identified published articles assessing the sensitivity and specificity of FIT for advanced neoplasia or CRC among populations under age 50. Following the search, 3 studies were included in the systematic review. Sensitivity to detect advanced neoplasia ranged from 0.19 to 0.36 and specificity between 0.94 and 0.97 and the overall sensitivity and specificity were 0.23 (0.17-0.30) and 0.96 (0.94-0.98), respectively. Two studies that assessed these metrics in multiple age categories found similar sensitivity and specificity across all age groups 30-49. Sensitivity and specificity to detect CRC was assessed in one study and found no significant differences by age groups. These results suggest that FIT performance may be lower for younger individuals compared to those typically screened for CRC. However, there were few studies available for analysis. Given increasing recommendations to expand screening in younger age groups, more research is needed to determine whether FIT is an adequate screening tool in this population.

Understanding real-world treatment patterns and clinical outcomes in AL amyloidosis patients diagnosed in Canada: A population-based cohort study.

Amyloid light chain (AL) amyloidosis is a rare and chronic bone marrow disorder. Existing claims data can be used to help understand the real-world treatment patterns and outcomes of this patient population. Various population-based administrative databases in Alberta, Canada were queried from 2010 to mid-2019 to identify cases of AL amyloidosis. Baseline patient and disease characteristics, sequencing of pharmacologic therapies, overall survival, and healthcare resource utilization were evaluated. A total of 215 individuals with AL amyloidosis were included. Among patients diagnosed between 2012 and 2019, 149 (85.1%) initiated first-line, 67 (38.3%) initiated second-line, 22 (12.6%) initiated third-line, and 11 (6.3%) initiated fourth-line systemic therapy. In the first-line setting, 99/149 (66.4%) received bortezomib, cyclophosphamide, and dexamethasone (CyBorD) and 21/149 (14.1%) received another bortezomib-based regimen. Survival from time of diagnosis improved over time, with a median overall survival of 25.8 months (95% CI: 9.8, 57.1) for individuals diagnosed in 2010-2011 versus 52.1 months (95% CI: 25.6, NA) for those diagnosed in 2012-2019. Despite this improvement, the proportion of individuals diagnosed in 2012-2019 who survived beyond five-years remained low (5-year survival: 48.4%; 95% CI: 40.9, 57.2) which highlights an unmet need for more efficacious therapies.

Prevalence, Treatment Patterns, and Outcomes of Individuals with EGFR Positive Metastatic Non-Small Cell Lung Cancer in a Canadian Real-World Setting: A Comparison of Exon 19 Deletion, L858R, and Exon 20 Insertion EGFR Mutation Carriers.

Real-world evidence surrounding EGFR positive NSCLC patients in Canada is limited. Administrative databases in Alberta, Canada were used to evaluate EGFR testing and mutation prevalence in de novo metastatic NSCLC, as well as the characteristics, treatment patterns, and outcomes of individuals with Exon 19, L858R and Exon20ins mutations. Between 2013-2019, 2974 individuals underwent EGFR testing, of which 451 (15.2%) were EGFR positive. Among EGFR positive individuals, 221 (49.0%) had an Exon 19 mutation, 159 (35.3%) had an L858R mutation, and 18 (4%) had an Exon20ins mutation. The proportion of individuals who initiated 1L systemic therapy was 89.1% for Exon19, 85.5% for L858R, and 72.2% for Exon20ins carriers. The primary front-line systemic therapy was gefitinib or afatinib monotherapy for individuals with Exon 19 (93.4%) and L858R (94.1%) mutations versus platinum combination therapy for individuals with Exon20ins mutations (61.5%). The Exon20ins cohort had worse median overall survival from initiation of 1L systemic therapy (10.5 months [95% CI: 8.0-not estimable]) than the Exon19 (20.6 months [95% CI: 18.4-24.9]), and L858R cohorts (19.1 months [95% CI: 14.5-23.1]). These findings highlight that Exon20ins mutations represent a rare subset of NSCLC in which treatment options are limited and survival outcomes are worse relative to individuals with more common types of EGFR mutations.

An exposure-response meta-analysis of ambient PM2.5 during pregnancy and preeclampsia.

Relationships between PM2.5 exposure and preeclampsia have been the focus of four recent systematic reviews and meta-analyses. We expand on knowledge gaps in these reviews by characterizing the shape of the exposure-outcome relationship, and by assessing the heterogeneity in these associations by study characteristics. Studies of PM2.5 and preeclampsia were identified from reviews, and confounder-adjusted estimates were extracted. Estimates were derived using a random-effects model. Potential non-linearity was evaluated using a one-stage dose-response meta-analysis. Contrary to previous meta-analyses reporting stronger relationships, the overall adjusted relative risk (RR) for a 10 µg/m3 average increase in PM2.5 during pregnancy and preeclampsia was modest and not statistically significant (RR: 1.07, 95% CI: 0.99-1.15). This was mainly attributable to inclusion/exclusion decisions for studies made during this review. In addition, there was no evidence of non-linearity, and no important sub-group differences by characteristics such as region, exposure assessment, participant exclusions, and early versus late-onset preeclampsia. Overall, our analysis suggests a modest relationship between ambient PM2.5 and preeclampsia. We provide details on inclusion and exclusion decisions that were lacking in previous studies, and report novel investigations of non-linearity and heterogeneity.

Ambient air pollution and inflammatory effects in a Canadian pregnancy cohort.

BACKGROUND: Epidemiologic studies have consistently reported associations between air pollution and pregnancy outcomes including preeclampsia and gestational diabetes. However, the biologic mechanisms underlying these relationships remain unclear as few studies have collected relevant biomarker data. We examined relationships between ambient PM2.5 and NO2 with markers of inflammation during pregnancy in a prospective cohort of Canadian women. METHODS: We analyzed data from 1170 women enrolled in the Maternal-Infant Research on Environmental Chemicals study. Daily residential PM2.5 and NO2 exposures during pregnancy were estimated using satellite-based and land-use regression models and used to create 14-day and 30-day exposure windows before blood-draw. Inflammatory markers C-reactive protein, interleukin-6, interleukin-8, and tumor necrosis factor-α were measured in third trimester plasma samples. Multivariable linear regression was used to estimate associations for an interquartile range (IQR) increase in PM2.5 and NO2 and markers of inflammation, while adjusting for individual-level confounders. RESULTS: Fourteen-day (IQR: 6.85 µg/m3) and 30-day (IQR: 6.15 µg/m3) average PM2.5 exposures before blood-draw were positively associated with C-reactive protein after adjustment for covariates (24.6% [95% CI = 9.4, 41.9] and 17.4% [95% CI = 1.0, 35.0] increases, respectively). This association was found to be robust in several sensitivity analyses. Neither PM2.5 nor NO2 exposures were associated with interleukin-6, interleukin-8, or tumor necrosis factor-α. CONCLUSION: Exposure to ambient PM2.5 is positively associated with maternal inflammatory pathways in late pregnancy. This may contribute to positive associations between ambient PM2.5 and risk of adverse pregnancy outcomes.

Simulation study on the validity of the average risk approach in estimating population attributable fractions for continuous exposures.

BACKGROUND: The population attributable fraction (PAF) is an important metric for estimating disease burden associated with causal risk factors. In an International Agency for Research on Cancer working group report, an approach was introduced to estimate the PAF using the average of a continuous exposure and the incremental relative risk (RR) per unit. This 'average risk' approach has been subsequently applied in several studies conducted worldwide. However, no investigation of the validity of this method has been done. OBJECTIVE: To examine the validity and the potential magnitude of bias of the average risk approach. METHODS: We established analytically that the direction of the bias is determined by the shape of the RR function. We then used simulation models based on a variety of risk exposure distributions and a range of RR per unit. We estimated the unbiased PAF from integrating the exposure distribution and RR, and the PAF using the average risk approach. We examined the absolute and relative bias as the direct and relative difference in PAF estimated from the two approaches. We also examined the bias of the average risk approach using real-world data from the Canadian Population Attributable Risk of Cancer study. RESULTS: The average risk approach involves bias, which is underestimation or overestimation with a convex or concave RR function (a risk profile that increases more/less rapidly at higher levels of exposure). The magnitude of the bias is affected by the exposure distribution as well as the value of RR. This approach is approximately valid when the RR per unit is small or the RR function is approximately linear. The absolute and relative bias can both be large when RR is not small and the exposure distribution is skewed. CONCLUSIONS: We recommend that caution be taken when using the average risk approach to estimate PAF.

Estimation of unregistered patients who left without being seen: At an urban mid-sized Canadian community emergency department.

OBJECTIVE: To determine whether changes to the appearance of an emergency department (ED) waiting room influenced the number of patients who left without being seen (LWBS). DESIGN: Retrospective analysis using National Ambulatory Care Reporting System data collected at the time of patient registration. SETTING: The ED of Belleville General Hospital, a mid-sized secondary care community hospital in Ontario with a catchment population of 125 000. PARTICIPANTS: All unscheduled patients registering at the hospital to be seen in the ED from July 1 to December 31, 2016 (control period), and from July 1 to December 31, 2017 (study period). MAIN OUTCOME MEASURES: The volume of patients registering by Canadian Triage and Acuity Scale (CTAS) level to be seen in the ED during the study period compared with the volume of patients registering during the control period, and the number of LWBS during the 2 time periods. RESULTS: The average number of patients registered per month was significantly greater in the study period than in the control period (t 10 = -5.53, P < .01). A total increase of 1881 registrations was recorded in the study period, or 10.47% (increase per month ranged from 9.59% to 11.66%). The proportion of patients with less acute triage scores decreased in the study period; however, the differences in CTAS levels between the 2 years was not statistically significant (χ 2 = 1.05, P = .90). The number of LWBS according to CTAS level was lower in all categories in the study period, including those in the less acute levels, decreasing from 60 in CTAS 5 in 2016 to 45 in 2017, and 585 in CTAS 4 in 2016 to 330 in 2017. Overall, the distribution of LWBS by CTAS level was significantly different between the control and study periods (P < .01). CONCLUSION: The number of patients registering is influenced by the apparent high or low occupancy of the waiting area at the time of registration.

Effect of a physician assistant on quality and efficiency metrics in an emergency department: Population cohort study.

OBJECTIVE: To determine the effect of a physician assistant (PA) working in a secondary care hospital emergency department (ED) on the overall performance of the ED. DESIGN: A retrospective review of ED data from April 1, 2017, to September 30, 2017. SETTING: Belleville General Hospital, a secondary care hospital, ED in Ontario. PARTICIPANTS: A physician assistant, 13 emergency physicians, and 7 family physicians. MAIN OUTCOME MEASURES: Overall ED performance was evaluated using metrics from the Ontario Ministry of Health and Long-Term Care: rate of patients who left without being seen, provider initial assessment time at the 90th percentile, and the average provider initial assessment time for all patients over a 6-month period. RESULTS: In the PA group, there was a lower average daily left without being seen rate (3.4% vs 5.2%; P < .001), a lower provider initial assessment time at the 90th percentile (3.9 hours vs 4.5 hours; P < .001), a lower average provider initial assessment time (114.83 minutes vs 139.46 minutes; P < .001), and a lower average length of stay (313.85 minutes vs 348.91 minutes; P < .001). CONCLUSION: This study suggests that a PA has a statistically significant positive effect on the overall performance of an ED. Future studies should examine the effect of a PA on quality of care and hospital funding.

Pollutant-sex specific differences in respiratory hospitalization and mortality risk attributable to short-term exposure to ambient air pollution.

BACKGROUND: Many studies have reported associations of individual pollutants with respiratory hospitalization and mortality based on different populations, which makes it difficult to directly compare adverse health effects among multiple air pollutants. OBJECTIVES: The study goal is to compare acute respiratory-related hospitalization and mortality associated with short-term exposure to three ambient air pollutants and analyze differences in health risks by season, age and sex. METHODS: Hourly measurements of air pollutants (ozone, NO2, PM2.5) and temperature were collected from ground-monitors for 24 cities along with daily hospitalization (1996-2012) and mortality (1984-2012) data. National associations between air pollutant and health outcome were estimated for season (warm, cold vs. year-round), age (base ≥ 1, seniors > 65), and sex (females ≥ 1 and males ≥ 1) using Bayesian hierarchical models. RESULTS: Overall, the three air pollutants were significantly associated with acute respiratory health outcomes at different lag-days. For respiratory hospitalization, the increased risks in percent changes with 95% posterior intervals for a 10-unit increase in each pollutant were: ozone (lag1, 0.7% (0.4, 0.9)), NO2 (lag0, 0.7% (0.1, 1.4)), and PM2.5 (lag1, 1.3% (0.7, 1.9)). For respiratory mortality: ozone (lag2, 1.2% (0.4, 1.9)), NO2 (lag1, 2.1% (0.6, 3.5)), and PM2.5 (lag1, 0.6% (-1.0, 2.2)). While some differences in risk were observed by season and age group, sex-specific differences were more pronounced. Compared with males, females had a higher respiratory mortality risk (1.8% (0.6, 2.9) vs 0.5% (-0.3, 1.3)) from ozone, a higher respiratory hospitalization risk (0.9% (0.0, 1.8) vs 0.6% (-0.3, 1.4)) but lower mortality risk (1.4% (-1.0, 3.7) vs 2.2% (0.4, 4.0)) from NO2, and a lower hospitalization risk (0.7% (-0.2, 1.7) vs 1.8% (1.0, 2.6)) from PM2.5. CONCLUSION: This study reports significant health effects of short-term exposure to three ambient air pollutants on respiratory hospitalization (ozone≈NO2 < PM2.5 per-10 unit; ozone>NO2 ≈ PM2.5 per-IQR) and mortality (ozone≈NO2 > PM2.5) in Canada. Pollutant-sex-specific differences were found, but inconclusive due to limited biological and physiological explanations. Further studies are warranted to understand the pollutant-sex specific differences.

Comparison of hospitalization and mortality associated with short-term exposure to ambient ozone and PM2.5 in Canada.

BACKGROUND: Hospitalization and mortality (H-M) have been linked to air pollution separately. However, previous studies have not adequately compared whether air pollution is a stronger risk factor for hospitalization or mortality. This study aimed to investigate differences in H-M risk from short-term ozone and PM2.5 exposures, and determine whether differences are modified by season, age, and sex. METHODS: Daily ozone, PM2.5, temperature, and all-cause H-M counts (ICD-10, A00-R99) were collected for 22-24 Canadian cities for up to 29 years. Generalized additive Poisson models were employed to estimate associations between each pollutant and health outcome, which were compared across season (warm, cold, or year-round), age (all ages or seniors > 65), and sex. RESULTS: Overall, ozone and PM2.5 showed higher season-specific risk of mortality than hospitalization: warm-season ozone: 0.54% (95% credible interval, 0.20, 0.85) vs. 0.14% (0.02, 0.27) per 10 ppb; and year-round PM2.5: 0.90% (0.33, 1.41) vs. 0.29% (0.03, 0.56) per 10 µg/m3. While age showed little H-M difference, sex appeared to be a modifier of H-M risk. While females had higher mortality risk, males had higher hospitalization risk: for females, ozone 0.87% (0.36, 1.35) vs. -0.03% (-0.18, 0.11) and PM2.5 1.19% (0.40, 1.90) vs. 0.19% (-0.10, 0.47); and for males ozone 0.20% (-0.28, 0.65) vs. 0.35% (0.18, 0.51). CONCLUSION: This study found H-M differences attributable to ozone and PM2.5, suggesting that both are stronger risk factors for mortality than hospitalization. In addition, there were clear H-M differences by sex: specifically, females showed higher mortality risk and males showed higher hospitalization risk.

The relationship between colorectal cancer risk factors and LINE-1 DNA methylation in healthy colon tissue.

Aim: LINE-1 DNA methylation is a modifiable epigenetic process linked to colorectal cancer (CRC). However, studies of methylation in the tissue of interest are limited. This research examines associations between CRC risk factors and LINE-1 DNA methylation in healthy colon tissue. Materials & methods: LINE-1 methylation was measured in colon tissue samples from 317 patients undergoing a screening colonoscopy. Associations were examined with established CRC risk factors including alcohol consumption, smoking, BMI, NSAIDs, physical activity and fruit and vegetable consumption. Results: All studied risk factors were not related to LINE-1 DNA methylation in this population. Conclusion: The observed results may reflect that the effect of this set of established risk factors is not mediated through LINE-1 DNA methylation in the healthy colon.

Scoping Review of the Potential Health Effects of Exposure to Extremely Low-Frequency Electric and Magnetic Fields.

Previous studies suggest that extremely low-frequency (ELF) electric and magnetic fields (EMFs) may impact human health. However, epidemiologic studies have provided inconsistent results on the association between exposure to ELF EMFs and various health outcomes. This scoping review reports on primary investigations that were published during the ten-year period of 2007-2017 on the association between ELF EMFs and cancer, cardiovascular disease (CVD), reproductive health effects, and neurodegenerative diseases. We identified a total of 361 articles from two bibliographic databases (PubMed and EMBASE). Of these, 39 articles (19 cancer studies, two CVD studies, nine reproductive health studies, and ten neurodegenerative disease studies [with one repeated for two outcomes]) met inclusion criteria. Articles identified in this study focus on three different types of exposure: occupational (22 studies), residential (15 studies), and electric blanket (two studies). This review suggests that ELF EMFs may be associated with neurodegenerative diseases, specifically Alzheimer's disease; however, limited evidence was found to suggest that ELF EMFs are associated with several types of cancer, CVD, and reproductive outcomes. Additional epidemiological studies in large study populations with improved exposure assessments are needed to clarify current inconclusive relationships.

Estimates of the current and future burden of lung cancer attributable to residential radon exposure in Canada.

Radon is widely recognized as a human carcinogen and findings from epidemiologic studies support a causal association between residential radon exposure and lung cancer risk. Our aim was to derive population attributable risks (PAR) to estimate the numbers of incident lung cancer due to residential radon exposure in Canada in 2015. Potential impact fractions for 2042 were estimated based on a series of counterfactuals. A meta-analysis was conducted to estimate the relative risk of lung cancer per 100 Becquerels (Bq)/m3 increase in residential radon exposure, with a pooled estimate of 1.16 (95% CI: 1.07-1.24). The population distribution of annual residential radon exposure was estimated based on a national survey with adjustment for changes in the population distribution over time, the proportion of Canadians living in high-rise buildings, and to reflect annual rather than winter levels. An estimated 6.9% of lung cancer cases in 2015 were attributable to exposure to residential radon, accounting for 1741 attributable cases. If mitigation efforts were to reduce all residential radon exposures that are above current Canadian policy guidelines of 200 Bq/m3 (3% of Canadians) to 50 Bq/m3, 293 cases could be prevented in 2042, and 2322 cumulative cases could be prevented between 2016 and 2042. Our results show that mitigation that exclusively targets Canadian homes with radon exposures above current Canadian guidelines may not greatly alleviate the future projected lung cancer burden. Mitigation of residential radon levels below current guidelines may be required to substantially reduce the overall lung cancer burden in the Canadian population.

The current and future burden of cancer attributable to modifiable risk factors in Canada: Summary of results.

Nearly one in two Canadians are expected to be diagnosed with cancer in their lifetime. However, there are opportunities to reduce the impact of modifiable cancer risk factors through well-informed interventions and policies. Since no comprehensive Canadian estimates have been available previously, we estimated the proportion of cancer diagnosed in 2015 and the future burden in 2042 attributable to lifestyle and environmental factors, and infections. Population-based historical estimates of exposure prevalence and their associated risks for each exposure-cancer site pair were obtained to estimate population attributable risks, assuming the exposures were distributed independently and that the risk estimates were multiplicative. We estimated that between 33 and 37% (up to 70,000 cases) of incident cancer cases among adults aged 30 years and over in 2015 were attributable to preventable risk factors. Similar proportions of cancer cases in males (34%) and females (33%) were attributable to these risk factors. Tobacco smoking and a lack of physical activity were associated with the highest proportions of cancer cases. Cancers with the highest number of preventable cases were lung (20,100), colorectal (9800) and female breast (5300) cancer. If current trends in the prevalence of preventable risk factors continue into the future, we project that by 2042 approximately 102,000 incident cancer cases are expected to be attributable to these risk factors per year, which would account for roughly one-third of all incident cancers. Through various risk reduction interventions, policies and public health campaigns, an estimated 10,600 to 39,700 cancer cases per year could be prevented by 2042.

Estimates of the current and future burden of lung cancer attributable to PM2.5 in Canada.

The International Agency for Research on Cancer has classified PM2.5 (fine particulate matter, PM2.5) as a lung cancer carcinogen in humans. We estimated the proportion of lung cancer cases attributable to PM2.5 exposure in Canada in 2015, and future avoidable cancers over the period 2016-2042 under different future exposure scenarios. A meta-analysis was conducted to estimate the relative risk of lung cancer associated with PM2.5 that was generalizable to Canada. A population-weighted Canadian distribution of residential PM2.5 exposure was estimated annually using ecological-level, satellite-derived PM2.5 data for the period 1990 to 2009. Population attributable risks (PAR) were estimated for PM2.5 and applied to lung cancer incidence from the Canadian Cancer Registry. Potential impact fractions based on counterfactual scenarios for the year 2042 were estimated, along with cumulative preventable cases from 2016 to 2042. The relative risk of lung cancer associated with PM2.5 was 1.09 (95% CI: 1.06-1.12) per an increase of 10 µg/m3. The average population-weighted exposure to PM2.5 corresponding to a 20-year exposure window from 1990 to 2009 was 8.3 µg/m3. The PAR for PM2.5 was estimated at 6.9%, accounting for 1739 attributable lung cancer cases in 2015. If patterns of decline in PM2.5 continue, over 3000 lung cancer cases could be prevented between 2016 and 2042. Exposure to PM2.5 contributes to a considerable burden of lung cancer in Canada and policies aimed at sustaining outdoor PM2.5 declines are important for lung cancer prevention in Canada.