Cancer incidence attributable to excess body weight in Alberta in 2012

Trends in the Incidence of Cancer Among Adolescent and Young Adults in Alberta, 1983-2017: A Population-Based Study Using Cancer Registry Data

Purpose: To describe the cancer incidence burden and trends among adolescent and young adults (AYAs) in Alberta, Canada over a 35-year period. Methods: We obtained data from the Alberta Cancer Registry on all first primary cancers, excluding non-melanoma skin cancer, diagnosed at ages 15-39 years among residents in Alberta from 1983 to 2017. Cancers were classified by using Barr's AYA cancer classification system. Age-standardized incidence rates (ASIR) and the average annual percentage change (AAPC) in incidence rates were calculated. Statistically significant changes in the AAPC during the study period were assessed using Joinpoint regression. Results: Overall, 23,652 incident cases of AYA cancer were diagnosed in Alberta. Females accounted for ∼60% of the diagnoses. AYA cancer increased significantly over the study period overall (AAPC: 0.5%; 95%CI: 0.3%-0.7%), for each sex (AAPC_male: 0.7%; 95%CI: 0.4%-0.9%; AAPC_female: 0.4%; 95%CI: 0.2%-0.6%), and among male and female 20-39 year-olds. Although statistically significant increases were observed in 11 out of 29 cancer sites for at least a portion of the study period, with significant AAPCs ranging from 0.8% (95%CI: 0.01%-1.5%) to 6.6% (95%CI: 4.6%-8.5%), the main driver was thyroid cancer (AAPC: 3.7%; 95%CI: 3.2%-4.2%). Statistically significant decreases were observed for six cancer sites, with AAPCs ranging from -6.4% (95%CI: -8.7% to -4.1%) to -1.1% (95%CI: -1.8% to -0.5%). Conclusions: There is a growing cancer burden among AYAs in Alberta, which is driven primarily by thyroid cancer and early-onset cancers in males. These results highlight the need for etiological studies and tertiary strategies to prevent and mitigate morbidity and mortality in the AYA population.

A Prospective Analysis of Plasma Phospholipid Fatty Acids and Breast Cancer Risk in 2 Provinces in Canada

BACKGROUND

Studies suggest that fatty acid status influences breast cancer etiology, yet the roles of individual fatty acids in breast cancer risk are unclear, specifically when central adiposity and menopausal status are considered.

OBJECTIVES

This study examined the associations of fatty acid status with breast cancer risk including location, menopausal status, and waist-to-hip ratio as key variables.

METHODS

Prediagnostic plasma phospholipid fatty acids were measured in women with breast cancer (n = 393) and age-matched controls (n = 786) from a nested case-control prospective study within Alberta's Tomorrow Project (ATP) and British Columbia Generations Project (BCGP) cohorts. Binary logistic regression models were used to evaluate associations of fatty acids and breast cancer risk with subgroup analysis for menopausal status and waist-to-hip ratio.

RESULTS

Women from BCGP had a higher n-3 (ɷ-3) fatty acid status compared with the ATP (6.4% ± 0.08% vs. 5.3% ± 0.06%; P < 0.001), so subsequent analysis was blocked by cohort. Overall, fatty acids had inconsistent associations with risk. In the ATP among premenopausal women, total long-chain n-3 fatty acids (ORQ4vsQ1 = 1.78; 95% CI: 0.58, 5.43; P-trend = 0.007, P-interaction = 0.07) were positively associated with breast cancer risk, whereas in BCGP, DHA (ORQ4vsQ1 = 0.66; 95% CI: 0.28, 1.53; P-trend = 0.03, P-interaction = 0.05) and total long-chain n-3 fatty acids (ORQ4vsQ1 = 0.66; 95% CI: 0.28, 1.54; P-trend = 0.03) were associated with decreased cancer risk when the waist-to-hip ratio was <0.85.

CONCLUSIONS

Our findings suggest that regional variations in fatty acid status influence breast cancer risk, resulting in positive associations of total long-chain n-3 fatty acids in premenopausal ATP women and negative associations of these fatty acids in BCGP women with a waist-to-hip ratio below guidelines. This study highlights the complexity and difficulty in using fatty acid status to predict breast cancer risk in diverse populations without the consideration of other risk factors.

Proportion of Cancer Cases Attributable to Excess Body Weight by US State, 2011-2015

Importance

Excess body weight (EBW) is an established cause of cancer. Despite variations in the prevalence of EBW among US states, there is little information on the EBW-related cancer burden by state; this information would be useful for setting priorities for cancer-control initiatives.

Objective

To calculate the population attributable fraction (PAF) of incident cancer cases attributable to EBW among adults 30 years or older in 2011 to 2015 in all 50 states and the District of Columbia.

Design, Setting, and Participants

State-level, self-reported body mass index (BMI [calculated as weight in kilograms divided by height in meters squared]) data from the Behavioral Risk Factor Surveillance System were adjusted by sex, age, race/ethnicity, and education using objectively measured BMI values from the National Health and Nutrition Examination Survey. Age- and sex-specific cancer incidence data by state were obtained from the US Cancer Statistics database. All analyses were performed between February 15, 2018, and July 17, 2018.

Main Outcomes and Measures

Sex-, age-, and state-specific adjusted prevalence estimates for 4 high BMI categories and corresponding relative risks from large-scale pooled analyses or meta-analyses were used to compute the PAFs for each US state for esophageal adenocarcinoma, multiple myeloma, and cancers of the gastric cardia, colorectum, liver, gallbladder, pancreas, female breast, corpus uteri, ovary, kidney and renal pelvis, and thyroid.

Results

Each year, an estimated 37 670 cancer cases in men (4.7% of all cancer cases excluding nonmelanoma skin cancers) and 74 690 cancer cases in women (9.6%) 30 years or older in the United States were attributable to EBW from 2011 to 2015. In both men and women, there was at least a 1.5-fold difference in the proportions of cancers attributable to EBW between states with the highest and lowest PAFs. Among men, the PAF ranged from 3.9% (95% CI, 3.6%-4.3%) in Montana to 6.0% (95% CI, 5.6%-6.4%) in Texas. The PAF for women was approximately twice as high as for men, ranging from 7.1% (95% CI, 6.7%-7.6%) in Hawaii to 11.4% (95% CI, 10.7%-12.2%) in the District of Columbia. The largest PAFs were found mostly in southern and midwestern states, as well as Alaska and the District of Columbia.

Conclusions and Relevance

The proportion of cancers attributable to EBW varies among states, but EBW accounts for at least 1 in 17 of all incident cancers in each state. Broad implementation of known community- and individual-level interventions is needed to reduce access to and marketing of unhealthy foods (eg, through a tax on sugary drinks) and to promote and increase access to healthy foods and physical activity, as well as preventive care.

Estimates of the current and future burden of cancer attributable to excess body weight and abdominal adiposity in Canada

The increasing prevalence of obesity among Canadians has important implications for newly diagnosed cases of cancer given that excess body weight and abdominal adiposity are known to increase the risk of several cancers. The purpose of this analysis was to estimate the current attributable and future avoidable burden of cancer related to excess body weight and abdominal adiposity among Canadian adults. We estimated the population attributable risk (PAR) for all cancers associated with excess body weight and abdominal adiposity using contemporary cancer incidence, relative risk and exposure prevalence data for body mass index (BMI), waist circumference and waist-to-hip-ratio. Using the partial impact fraction (PIF), we also estimated the future avoidable burden of cancer from 2015 to 2042 in Canada, and by province, through various hypothetical intervention scenarios. In 2003, approximately half (50.5%) of the Canadian population was estimated to be overweight (BMI 25.0-29.9) or obese (BMI ≥30.0), 56.5% to have excess abdominal adiposity and 56.8% with a high waist-to-hip ratio. In 2015, the estimated PARs of all incident cancers associated with excess body weight, excess abdominal adiposity and high waist-to-hip ratio were 7.2%, 8.9% and 10.0%, respectively. If the population BMI could revert to its 1994 distribution, 72,157 associated cancer cases could be prevented cumulatively by 2042. A reduction in excess body weight and abdominal adiposity has the potential to decrease the future cancer burden in Canada substantially, and hence efforts to reverse increasing trends in obesity should be prioritized.

The preventable burden of endometrial and ovarian cancers in Australia: A pooled cohort study

OBJECTIVE

Evidence on the endometrial and ovarian cancer burden preventable through modifications to current causal behavioural and hormonal exposures is limited. Whether the burden differs by population subgroup is unknown.

METHODS

We linked pooled data from six Australian cohort studies to national cancer and death registries, and quantified exposure-cancer associations using adjusted proportional hazards models. We estimated exposure prevalence from representative health surveys. We then calculated Population Attributable Fractions (PAFs) with 95% confidence intervals (CIs), accounting for competing risk of death, and compared PAFs for population subgroups.

RESULTS

During a median 4.9 years follow-up, 510 incident endometrial and 303 ovarian cancers were diagnosed. Overweight and obesity explained 41.9% (95% CI 32.3-50.1) of the endometrial cancer burden and obesity alone 34.5% (95% CI 27.5-40.9). This translates to 12,800 and 10,500 endometrial cancers in Australia in the next 10 years, respectively. The body fatness-related endometrial cancer burden was highest (49-87%) among women with diabetes, living remotely, of older age, lower socio-economic status or educational attainment and born in Australia. Never use of oral contraceptives (OCs) explained 8.1% (95% CI 1.8-14.1) or 2500 endometrial cancers. A higher BMI and current long-term MHT use increased, and long-term OC use decreased, the risk of ovarian cancer, but the burden attributable to overweight, obesity or exogenous hormonal factors was not statistically significant.

CONCLUSIONS

Excess body fatness, a trait that is of high and increasing prevalence globally, is responsible for a large proportion of the endometrial cancer burden, indicating the need for effective strategies to reduce adiposity.

Central body fatness is a stronger predictor of cancer risk than overall body size

The importance of body size versus weight distribution for cancer risk is unclear. We investigated associations between measures of body size and shape and the risk of developing cancer. The study population consisted of 26,607 participants from the Alberta’s Tomorrow Project cohort. Two main measures of body shape and size were examined: i) body mass index (BMI) and ii) waist circumference (WC). Incident cancers were identified via linkage to the Alberta Cancer Registry. Cox proportional hazards models were used. Males and females classified as obese (BMI ≥ 30 kg /m⁻²) have a 33% and 22% increased risk of all-cancer, respectively, than their normal weight counterparts. Similar all-cancer risk increases are observed for those above sex-specific WC guidelines. Mutual adjustment for WC attenuates the association between BMI and all-cancer risk, especially among females. Central adiposity appears to be a stronger predictor of all-cancer risk than body size.

Obesity is linked to increased cancer risk but the impact of body size versus weight distribution in determining the increased risk is unclear. Here the authors examined body mass index, waist circumference, and waist to hip ratio in relation to all-cancer incidence and incidence of seven individual cancers in a population of approximately 26,000 individual and conclude that central adiposity appears to be a stronger predictor of all-cancer risk than body size.

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.

Organization of future training in bariatric gastroenterology

A world-wide rise in the prevalence of obesity continues. This rise increases the occurrence of, risks of, and costs of treating obesity-related medical conditions. Diet and activity programs are largely inadequate for the long-term treatment of medically-complicated obesity. Physicians who deliver gastrointestinal care after completing traditional training programs, including gastroenterologists and general surgeons, are not uniformly trained in or familiar with available bariatric care. It is certain that gastrointestinal physicians will incorporate new endoscopic methods into their practice for the treatment of individuals with medically-complicated obesity, although the long-term impact of these endoscopic techniques remains under investigation. It is presently unclear whether gastrointestinal physicians will be able to provide or coordinate important allied services in bariatric surgery, endocrinology, nutrition, psychological evaluation and support, and social work. Obtaining longitudinal results examining the effectiveness of this ad hoc approach will likely be difficult, based on prior experience with other endoscopic measures, such as the adenoma detection rates from screening colonoscopy. As a long-term approach, development of a specific curriculum incorporating one year of subspecialty training in bariatrics to the present training of gastrointestinal fellows needs to be reconsidered. This approach should be facilitated by gastrointestinal trainees’ prior residency training in subspecialties that provide care for individuals with medical complications of obesity, including endocrinology, cardiology, nephrology, and neurology. Such training could incorporate additional rotations with collaborating providers in bariatric surgery, nutrition, and psychiatry. Since such training would be provided in accredited programs, longitudinal studies could be developed to examine the potential impact on accepted measures of care, such as complication rates, outcomes, and costs, in individuals with medically-complicated obesity.

Cancer incidence attributable to lifestyle and environmental factors in Alberta in 2012: summary of results

BACKGROUND

Estimates of the proportion of cancer cases that can be attributed to modifiable risk factors are not available for Canada and, more specifically, Alberta. The purpose of this study was to estimate the total proportion of cancer cases in Alberta in 2012 that could be attributed to a set of 24 modifiable lifestyle and environmental risk factors.

METHODS

We estimated summary population attributable risk estimates for 24 risk factors (smoking [both passive and active], overweight and obesity, inadequate physical activity, diet [inadequate fruit and vegetable consumption, inadequate fibre intake, excess red and processed meat consumption, salt consumption, inadequate calcium and vitamin D intake], alcohol, hormones [oral contraceptives and hormone therapy], infections [Epstein-Barr virus, hepatitis B and C viruses, human papillomavirus, Helicobacter pylori], air pollution, natural and artificial ultraviolet radiation, radon and water disinfection by-products) by combining population attributable risk estimates for each of the 24 factors that had been previously estimated. To account for the possibility that individual cancer cases were the result of a combination of multiple risk factors, we subtracted the population attributable risk for the first factor from 100% and then applied the population attributable risk for the second factor to the remaining proportion that was not attributable to the first factor. We repeated this process in sequential order for all relevant exposures.

RESULTS

Overall, an estimated 40.8% of cancer cases in Alberta in 2012 were attributable to modifiable lifestyle and environmental risk factors. The largest proportion of cancers were estimated to be attributable to tobacco smoking, physical inactivity and excess body weight. The summary population attributable risk estimate was slightly higher among women (42.4%) than among men (38.7%).

INTERPRETATION

About 41% of cancer cases in Alberta may be attributable to known modifiable lifestyle and environmental risk factors. Reducing the prevalence of these factors in the Alberta population has the potential to substantially reduce the provincial cancer burden.

Cancer incidence attributable to inadequate physical activity in Alberta in 2012

BACKGROUND

Physical inactivity has been consistently associated with increased risk of colorectal, endometrial, breast (in postmenopausal women), prostate, lung and ovarian cancers. The objective of the current analysis was to estimate the proportion and absolute number of site-specific cancer cases attributable to inadequate physical activity in Alberta in 2012.

METHODS

We used population attributable risks to estimate the proportion of each site-specific cancer attributable to inactivity. Relative risk estimates were obtained from the epidemiological literature, and prevalence estimates were calculated with the use of data from the Canadian Community Health Survey cycle 2.1 (2003). Respondents who acquired 1.5-2.9 kcal/kg per day and less than 1.5 kcal/kg per day of physical activity were classified as moderately active and inactive, respectively, and both levels were considered inadequate for mitigating cancer risks. We obtained age-, sex- and site-specific cancer incidence data from the Alberta Cancer Registry for 2012.

RESULTS

About 59%-75% of men and 69%-78% of women did not engage in adequate physical activity. Overall, 13.8% of cancers across all associated cancers were estimated to be attributable to inadequate physical activity, representing 7.2% of all cancers diagnosed in Alberta in 2012. Suboptimal levels of physical activity had a greater impact among women: the proportion of all associated cancers attributable to inadequate physical activity was 18.3% for women and 9.9% for men.

INTERPRETATION

A substantial proportion of cancer cases diagnosed in Alberta were estimated to be attributable to inadequate physical activity. With the high prevalence of physical inactivity among adults in the province, developing strategies to increase physical activity levels could have a notable impact on reducing future cancer burden in Alberta.