9. Cancers attributable to inadequate physical exercise in the UK in 2010

Young adult cancer risk behaviours originate in adolescence: a longitudinal analysis using ALSPAC, a UK birth cohort study

BACKGROUND

An estimated 40% of cancer cases in the UK in 2015 were attributable to cancer risk behaviours. Tobacco smoking, alcohol consumption, obesity, and unprotected sexual intercourse are known causes of cancer and there is strong evidence that physical inactivity is associated with cancer. These cancer risk behaviours co-occur however little is known about how they pattern longitudinally across adolescence and early adulthood. Using data from ALSPAC, a prospective population-based UK birth cohort study, we explored patterns of adolescent cancer risk behaviours and their associations with cancer risk behaviours in early adulthood.

METHODS

Six thousand three hundred fifty-one people (46.0% of ALSPAC participants) provided data on all cancer risk behaviours at one time during adolescence, 1951 provided data on all cancer risk behaviours at all time points. Our exposure measure was quartiles of a continuous score summarising cumulative exposure to cancer risk behaviours and longitudinal latent classes summarising distinct categories of adolescents exhibiting similar patterns of behaviours, between age 11 and 18 years. Using both exposure measures, odds of harmful drinking (Alcohol Use Disorders Identification Test-C ≥ 8),daily tobacco smoking, nicotine dependence (Fagerström test ≥4), obesity (BMI ≥30), high waist circumference (females: ≥80 cm and males: ≥94 cm, and high waist-hip ratio (females: ≥0.85 and males: ≥1.00) at age 24 were estimated using logistic regression analysis.

RESULTS

We found distinct groups of adolescents characterised by consistently high and consistently low engagement in cancer risk behaviours. After adjustment, adolescents in the top quartile had greater odds of all outcomes in early adulthood: nicotine dependency (odds ratio, OR = 5.37, 95% confidence interval, CI = 3.64-7.93); daily smoking (OR = 5.10, 95% CI =3.19-8.17); obesity (OR = 4.84, 95% CI = 3.33-7.03); high waist circumference (OR = 2.48, 95% CI = 1.94-3.16); harmful drinking (OR = 2.04, 95% CI = 1.57-2.65); and high waist-hip ratio (OR = 1.88, 95% CI = 1.30-2.71), compared to the bottom quartile. In latent class analysis, adolescents characterised by consistently high-risk behaviours throughout adolescence were at higher risk of all cancer risk behaviours at age 24, except harmful drinking.

CONCLUSIONS

Exposure to adolescent cancer risk behaviours greatly increased the odds of cancer risk behaviours in early adulthood. Interventions to reduce these behaviours should target multiple rather than single risk behaviours and should focus on adolescence.

Preventable causes of cancer in Texas by race/ethnicity: insufficient physical activity

Background

According to the 2018 Third Expert Report from the World Cancer Research Fund/American Institute for Cancer Research, there is strong evidence that physical activity of all types and intensities protects against colon, endometrial and breast cancers. We aimed to estimate the percentage and number of incident cancer cases diagnosed in Texas in 2015 that were attributable to insufficient physical activity, and we examined for differences across racial/ethnic subgroups to reveal important causes of and potential avenues for reductions to cancer health disparities.

Methods

We calculated population attributable fractions for cancers attributable to insufficient physical activity using prevalence data from the Texas Behavioral Risk Factor Surveillance System and relative risk estimates associated with insufficient physical activity from prior studies. Cancer incidence data were gathered from the Texas Cancer Registry.

Results

Overall, approximately 2.0% of all new cancers or 2094 excess cancer cases diagnosed in 2015 in Texans aged ≥25 years were attributable to insufficient physical activity, with more cancers in women (3.2%) than in men (0.8%). Of all cancer sites, the highest population attributable fraction for insufficient physical activity was observed for endometrial cancers (21.7% compared with 12.7% for colon cancers, 10.9% for premenopausal breast cancers and 2.0% for postmenopausal breast cancers). Hispanics (2.6%) and non-Hispanic blacks (2.5%) had higher proportions of cancers attributable to insufficient physical activity than non-Hispanic whites (1.8%).

Conclusions

Public health programmes should stress physical activity as a means of cancer prevention, especially among minority groups, who may have disproportionately higher percentages of cancers attributable to insufficient physical activity.

Summertime physiological and thermal responses among activity levels in campus outdoor spaces in a humid subtropical city

We identified physiological and thermal responses to different activity levels on a campus during summertime in Xi'an, a humid subtropical city in China. Physiological responses and thermal comfort of 54 healthy college students while undertaking different physical activities (light, moderate and vigorous intensities) in six campus open spaces were investigated using meteorological measures, longitudinal questionnaire surveys and physiological parameters. Physiological Equivalent Temperature (PET) and Universal Thermal Climate Index (UTCI) were chosen as the thermal indices, while blood pressure (BP), heart rate (HR) and skin temperature (ST) were selected as physiological evaluation measures. Results demonstrated that: 1) Types and proportions of thermal symptoms were positively related to outdoor spatial characteristics and physical activity levels. The proportion of thermal discomfort increased 33, 50 and 83% as activity intensities increased from light through moderate to vigorous. 2) BP and HR reflected human activity levels. HR clearly represented metabolic trends. 3) ST accurately represented physiological responses among spaces across activity levels. However, mean skin temperature (MST) was poorly related to thermal sensation vote (TSV). 4) As activity intensity ranged from light through moderate to vigorous, neutral UTCI declined by 27.6 °C, 25.6 °C, 22.0 °C, and neutral PET declined by 26.1 °C, 22.1 °C, 11.9 °C. 5) Outdoor spaces shaded by trees or pavilions were more comfortable for outdoor activities than these with low or middle SVF during summer.

Clustering of behavioural risk factors for health in UK adults in 2016: a cross-sectional survey

Background

Foods high in fat, sugar and salt (HFSS) are known to contribute to overweight and obesity. In addition to overweight and obesity, smoking, alcohol consumption and physical inactivity are known risk factors for non-communicable diseases, including several cancers and cardiovascular disease.

Methods

Secondary analysis of UK-representative cross-sectional survey data of 3293 adults aged 18+. Regression analyses were undertaken to understand the relationship between consumption of HFSS food and soft drinks, alcohol and tobacco and socio-demographics. Clustering analysis identified groupings of health risk factors.

Results

Males, those aged 18–24 and those from the more deprived groups consumed ready meals and fast food most frequently. Most of the sample (77.3%) engaged in at least one health risk behaviour. Six clusters were identified in the clustering analysis. Older (65+) female respondents were more likely to be inactive. Smokers exhibiting additional risk behaviours were more likely to be of working age from more deprived groups, and men over 65 were more likely to consume harmful levels of alcohol with additional risk factors.

Conclusion

Policies and services in the UK tend to focus on changing behaviour to address individual risk factors. This study shows that policies and interventions need to address multiple risk factors.

Addressing context to understand physical activity among Muslim university students: the role of gender, family, and culture

Background

Physical inactivity is a crucial risk factor for the development of chronic health issues, which have a high incidence among Arabs living in the Gulf Cooperation Council (GCC) countries. The Qatar Stepwise Survey 2012 reported that approximately 44% of young adults 18–44 years of age had insufficient levels of physical activity. Family is a powerful source of information and socialization for adolescents and has a strong influence on their attitudes, decision-making, and behaviors.

Methods

The purpose of this study is to understand how university students’ physical activity can be influenced by sociocultural factors, particularly family health values and Muslim Arab culture. Using the criterion sampling strategy, 20 undergraduate Muslim students (Female students =10, Male students = 10) aged from 18 to 23 years who were Qatari or born and also raised in Qatar were recruited and interviewed. Participants were asked if they consider themselves active or not, about their perception of family health values regarding physical activity and the factors shaping these values, and the influence of family values on their physical activity behavior. The interviews were transcribed verbatim, coded, and analyzed following inductive analysis.

Results

The majority of the participants were influenced by their family health values, which were shaped by Qatari culture and the culture of origin for non-Qatari and were implicitly shaped by Islam. Participants reported that their role models of physical activity were males (fathers and male siblings), a health condition will motivate their families to be physically active, and families give priority to work and academic achievement over physical activity. A few participants showed that there was explicit influence of Islam on their physical activity, because culture’s influence was veiling religion’s. Culture was seen as a facilitator for physical activity from the males’ perspectives, which was not the case for female participants who reported the negative influence of culture on their physical activity because of the limited choices available for them. Non-Qatari students revealed that their culture of origin (such as Syria, Palestine, Egypt, Somalia, Bangladesh, Sudan, Pakistan and India) was the dominant factor in shaping their family health values.

Conclusions

The findings address gaps in the literature about families’ health values regarding physical activity in Qatar, the influence of the different ecologies surrounding these values, and the physical activity behaviors of university students. Knowledge about these factors can aid in the development of family-based interventions designed to motivate adolescents to be physically active, which should be religion- and culture-tailored.

Cancers in France in 2015 attributable to insufficient physical activity

INTRODUCTION

Insufficient physical activity is a known risk factor for various co-morbidities, including cancer. Globally, its prevalence has increased markedly over the past decades. The aim of this study was to estimate the proportion and number of cancers that were attributable to insufficient physical activity in France in 2015.

METHODS

Population attributable fractions (PAFs) and numbers of cancer cases attributable to insufficient physical activity (<30 min daily of moderate-to-vigorous physical activity) were estimated by age, sex and cancer site. Assuming a 10-year lag-period, PAFs were calculated using physical activity prevalence from a cross-sectional French population survey and cancer-specific relative risks.

RESULTS

About half of all French adults were found to be insufficiently physically active, with great variation by age and sex. In 2015, an estimated 2973 cancer cases diagnosed in French adults aged 30y+ were attributable to insufficient physical activity, corresponding to 0.8% of all cancer cases (0.2% in men and 1.6% in women). This comprised 3.8% of all postmenopausal breast cancers (1620 cases), 3.6% of all colon cancers (902 cases) and 6.0% of all cancers of the corpus uteri (450 cases). If at least half of the recommended physical activity level was achieved, 1095 cancer cases could have been avoided.

CONCLUSION

Insufficient physical activity is associated to about 3000 cancer cases in France, a country with comparatively low but increasing prevalence of this risk factor. This result is important for setting priorities in cancer prevention programmes aiming to increase physical activity in France and Europe in general.

Estimates of the current and future burden of cancer attributable to lack of physical activity in Canada

Physical activity reduces the risk of many cancers, yet the prevalence of inadequate physical activity among Canadians remains high. Here we estimated the current attributable and future avoidable burden of cancer related to inadequate physical activity among Canadian adults. Population attributable risk (PAR) for all cancers associated with inadequate physical activity were estimated using relative risks obtained from comprehensive reports, meta-analyses and pooled analyses. Cancer incidence data were acquired from the Canadian Cancer Registry. Physical activity data were taken from Canadian Community Health Survey (Cycle 2.1, 2003), in which respondents were classified as "physically inactive" (<1.5 kcal/kg/day), "moderately active" (1.5-2.9 kcal/kg/day) or "physically active (≥3.0 kcal/kg/day). We defined "inadequate physical activity" as being either "physically inactive" or "moderately active" to determine the PAR of cancer due to inadequate physical activity. We estimated the future burden of inadequate physical activity using potential impact fractions and a series of intervention scenarios, including 10% to 50% reductions in inadequate physical activity from 2015 to 2042. For 2015, the total attributable burden due to inadequate physical activity for associated cancers was 10.6% and 4.9% for all cancers. A 50% reduction in inadequate physical activity could avoid 39,877 cumulative cases of cancer by 2042. Over 9000 cancer cases in 2015 were estimated to be attributable to inadequate physical activity and 5170 incident cases of cancer could be prevented with increases in physical activity levels by 2042. Policies aimed at increasing physical activity among Canadian could have a meaningful impact for cancer prevention.

Estimates of the current and future burden of cancer attributable to sedentary behavior in Canada

Leisure-time sedentary behavior is an emerging modifiable risk factor for cancer. We estimated the proportion of cancers attributed to leisure-time sedentary behavior as a separate risk factor from physical activity in Canada for 2015. We projected numbers of future avoidable cancers by 2042 using various assumed levels of reduced leisure-time sedentary behavior in the population. We calculated population attributable risks (PAR) for associated cancers and all-cancers associated with leisure-time sedentary behavior. Our analysis used pooled data on leisure-time sedentary behavior from the Canadian Community Health Survey (CCHS), and incident cancer data from the Canadian Cancer Registry (CCR). Survey respondents were categorized into three levels of leisure-time sedentary behavior, "<3 h/day", "≥3-<6 h/day", and "≥6 h/day". Estimates for the future burden of leisure-time sedentary behavior were calculated using the potential impact fractions framework (PIF) and counterfactual scenarios, from 10% to 50% decreases in leisure-time sedentary behavior. The estimated prevalence of leisure-time sedentary behavior at the highest level (≥6 h/day) in Canada during the 2000s was 9.9% among both sexes combined across age-groups. The total attributable burden due to leisure-time sedentary behavior was estimated to be 10.3% for associated cancers and 6.5% for all-cancers in 2015. A 50% reduction in leisure-time sedentary behavior across the Canadian population could avoid 4054 cancers by 2042. We estimated that over 3000 cancer cases in Canada were attributable to leisure-time sedentary behavior in 2015, and that that 4054 incident cancer cases could be prevented by 2042 with meaningful reductions in leisure-time sedentary behavior.

Avoidable cancers in the Nordic countries-the potential impact of increased physical activity on postmenopausal breast, colon and endometrial cancer

BACKGROUND

Physical activity has been shown to reduce the risk of colon, endometrial and postmenopausal breast cancer. The aim of this study was to quantify the proportion of the cancer burden in the Nordic countries linked to insufficient levels of leisure time physical activity and estimate the potential for cancer prevention for these three sites by increasing physical activity levels.

METHODS

Using the Prevent macrosimulation model, the number of cancer cases in the Nordic countries over a 30-year period (2016-2045) was modelled, under different scenarios of increasing physical activity levels in the population, and compared with the projected number of cases if constant physical activity prevailed. Physical activity (moderate and vigorous) was categorised according to metabolic equivalents (MET) hours in groups with sufficient physical activity (15+ MET-hours/week), low deficit (9 to <15 MET-hours/week), medium deficit (3 to <9 MET-hours/week) and high deficit (<3 MET-hours/week).

RESULTS

If no one had insufficient levels of physical activity, about 11,000 colon, endometrial and postmenopausal breast cancer cases could be avoided in the Nordic countries in a 30-year period, which is 1% of the expected cases for the three cancer types. With a 50% reduction in all deficit groups by 2025 or a 100% reduction in the group of high deficit, approximately 0.5% of the expected cases for the three cancer types could be avoided. The number and percentage of avoidable cases was highest for colon cancer.

CONCLUSION

11,000 cancer cases could be avoided in the Nordic countries in a 30-year period, if deficit in physical activity was eliminated.

Development and Validation of Lifestyle-Based Models to Predict Incidence of the Most Common Potentially Preventable Cancers

BACKGROUND

Most risk models for cancer are either specific to individual cancers or include complex or predominantly non-modifiable risk factors.

METHODS

We developed lifestyle-based models for the five cancers for which the most cases are potentially preventable through lifestyle change in the UK (lung, colorectal, bladder, kidney, and esophageal for men and breast, lung, colorectal, endometrial, and kidney for women). We selected lifestyle risk factors from the European Code against Cancer and obtained estimates of relative risks from meta-analyses of observational studies. We used mean values for risk factors from nationally representative samples and mean 10-year estimated absolute risks from routinely available sources. We then assessed the performance of the models in 23,768 participants in the EPIC-Norfolk cohort who had no history of the five selected cancers at baseline.

RESULTS

In men, the combined risk model showed good discrimination [AUC, 0.71; 95% confidence interval (CI), 0.69-0.73] and calibration. Discrimination was lower in women (AUC, 0.59; 95% CI, 0.57-0.61), but calibration was good. In both sexes, the individual models for lung cancer had the highest AUCs (0.83; 95% CI, 0.80-0.85 for men and 0.82; 95% CI, 0.76-0.87 for women). The lowest AUCs were for breast cancer in women and kidney cancer in men.

CONCLUSIONS

The discrimination and calibration of the models are both reasonable, with the discrimination for individual cancers comparable or better than many other published risk models.

IMPACT

These models could be used to demonstrate the potential impact of lifestyle change on risk of cancer to promote behavior change.

Preventable fractions of colon and breast cancers by increasing physical activity in Brazil: perspectives from plausible counterfactual scenarios

BACKGROUND

Physical activity is associated with lower risk of colon and breast cancers. Herein we estimated preventable fractions of colon and breast cancers in Brazil by increasing population-wide physical activity to different counterfactual scenarios.

METHODS

We used data from a representative national survey in Brazil and corresponding relative risks of colon and postmenopausal breast cancers from a meta-analysis. Estimated cancer incidence was retrieved from GLOBOCAN and Brazilian National Cancer Institute. Five counterfactual scenarios for physical activity were considered: (i) theoretical minimum risk exposure level (≥8,000 metabolic equivalent of tasks-minute/week - MET-min/week); (ii) physical activity recommendation (≥600 MET-min/week); (iii) a 10% reduction in prevalence of insufficient physical inactivity (<600 MET-min/week); (iv) physical activity level in each state equals the most active state in Brazil; (v) closing the gender differences in physical activity.

RESULTS

About 19% (3,630 cases) of colon cancers and 12% (6,712 cases) of postmenopausal breast cancers could be prevented by increasing physical activity to ≥8,000 MET-min/week. Plausible counterfactual scenarios suggested the following impact on cancer prevention: reaching physical activity recommendation: 1.7% (1,113 cases) of breast and 6% (1,137 cases) of colon; 10% reduction in physical inactivity prevalence: 0.2% (111 cases) of breast and 0.6% (114 cases) of colon; most active state scenario: 0.3% (168 cases) of breast and 1% (189 cases) of colon; reducing gender differences in physical activity: 1.1% (384 cases) of breast and 0.6% (122 cases) of colon.

CONCLUSIONS

High levels of physical activity are required to achieve a sizable impact on breast and colon cancer prevention in Brazil.

Leitzmann M, Brenner*2 H, Mons*2 U. Cancers Due to Excess Weight, Low Physical Activity, and Unhealthy Diet

BACKGROUND

Excess weight, low physical activity, low intakes of dietary fiber, fruits, and vegetables, and high meat and salt intake increase cancer risk.

METHODS

Numbers and proportions (population-attributable fractions, PAF) of incident cancer cases in Germany in 2018 attributable to these factors were estimated by sex and age groups for ages 35 to 84 years using population projections, national cancer incidence and exposure data, and published risk estimates.

RESULTS

Estimated numbers (percentages) of attributable cancers were 30 567 (7%) for excess weight, 27 081 (6%) for low physical activity, 14 474 (3%) for low dietary fiber intake, 9447 (2%) for low fruit and vegetable consumption, 9454 (2%) and 1687 (0.4%) for processed meat and high red meat consumption, respectively, and 1204 (0.3%) for high salt intake. Excess weight substantially contributed to endometrial, renal, and liver cancer (PAF = 24 to 35%). Low physical activity contributed to endometrial, renal, and lung cancer (PAF = 15 to 19%), and dietary factors mainly contributed to colorectal, breast, and lung cancer (PAF = 9 to 16%).

CONCLUSION

A considerable proportion of cancer cases are attributable to excess weight, physical inactivity, and unhealthy dietary habits. Major prevention efforts are needed to reduce the cancer incidence attributable to these avoidable factors.

Impact of known risk factors on endometrial cancer burden in Chinese women

This study aimed to provide data on the impact of known risk factors on endometrial cancer burden. Using data on 1199 endometrial cancer cases and 1212 frequency matched controls from a population-based case-control study carried out in urban Shanghai, China from 1997 to 2003, multivariable adjusted odds ratios were obtained from unconditional logistic regression analyses. Partial population-attributable risks were calculated and corresponding 95% confidence intervals were estimated using a bootstrap method. An estimated 16.94% of endometrial cancer cases were attributed to overweight or obesity; 8.39% to meat intake; 5.45% to nonregular tea drinking; 5.23% to physical inactivity; and 1.77% to family history of endometrial, breast, or colorectal cancers. Overall, these risk factors accounted for 36.01% (95% confidence interval: 28.55-43.11%) of total endometrial cancer cases. Similar results were observed when analysis was restricted to postmenopausal women. Among modifiable lifestyle factors, overweight and obesity accounted for the largest proportion of endometrial cancer in the study population. Lifestyle alterations, such as maintenance of healthy weight, regular exercise, consumption of less meat, and tea drinking, could potentially reduce endometrial cancer by more than one-third.

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.

Cancer incidence attributable to excess body weight in Alberta in 2012

BACKGROUND

Excess body weight has been consistently associated with colorectal, breast, endometrial, esophageal, gall bladder, pancreatic and kidney cancers. The objective of this analysis was to estimate the proportion of total and site-specific cancers attributable to excess body weight in adults in Alberta in 2012.

METHODS

We estimated the proportions of attributable cancers using population attributable risk. Risk estimates were obtained from recent meta-analyses, and exposure prevalence estimates were obtained from the Canadian Community Health Survey. People with a body mass index of 25.00-29.99 kg/m2 and of 30 kg/m2 or more were categorized as overweight and obese, respectively.

RESULTS

About 14%-47% of men and 9%-35% of women in Alberta were classified as either overweight or obese; the proportion increased with increasing age for both sexes. We estimate that roughly 17% and 12% of obesity-related cancers among men and women, respectively, could be attributed to excess body weight in Alberta in 2012. The heaviest absolute burden in terms of number of cases was seen for breast cancer among women and for colorectal cancer among men. Overall, about 5% of all cancers in adults in Alberta in 2012 were estimated to be attributable to excess body weight in 2000-2003.

INTERPRETATION

Excess body weight contributes to a substantial proportion of cases of cancers associated with overweight and obesity annually in Alberta. Strategies to improve energy imbalance and reduce the proportion of obese and overweight Albertans may have a notable impact on cancer incidence in the future.

The economic burden of cancers attributable to tobacco smoking, excess weight, alcohol use, and physical inactivity in Canada

OBJECTIVES

The purpose of the present study was to calculate the proportion of cancers in Canada attributable to tobacco smoking (ts), alcohol use (au), excess weight (ew), and physical inactivity (pia); to explore variation in the proportions of those risk factors (rfs) over time by sex and province; to estimate the economic burden of cancer attributable to the 4 rfs; and to calculate the potential reduction in cancers and economic burden if all provinces achieved rf prevalence rates equivalent to the best in Canada.

METHODS

We used a previously developed approach based on population-attributable fractions (pafs) to estimate the cancer-related economic burden associated with the four rfs. Sex-specific relative risk and age- and sex-specific prevalence data were used in the modelling. The economic burden was adjusted for potential double counting of cases and costs.

RESULTS

In Canada, 27.7% of incident cancer cases [95% confidence interval (ci): 22.6% to 32.9%] in 2013 [47,000 of 170,000 (95% ci: 38,400-55,900)] were attributable to the four rfs: ts, 15.2% (95% ci: 13.7% to 16.9%); ew, 5.1% (95% ci: 3.8% to 6.4%); au, 3.9% (95% ci: 2.4% to 5.3%); and pia, 3.5% (95% ci: 2.7% to 4.3%). The annual economic burden attributable to the 47,000 total cancers was $9.6 billion (95% ci: $7.8 billion to $11.3 billion): consisting of $1.7 billion in direct and $8.0 billion in indirect costs. Applying the lowest rf rates to each province would result in an annual reduction of 6204 cancers (13.2% of the potentially avoidable cancers) and a reduction in economic burden of $1.2 billion.

CONCLUSIONS

Despite substantial reductions in the prevalence and intensity of ts, ts remains the dominant risk factor from the perspective of cancer prevention in Canada, although ew and au are becoming increasingly important rfs.

The fractions of cancer attributable to modifiable factors: A global review

Worldwide, the burden of cancer is rising, stimulating efforts to develop strategies to control these diseases. Primary prevention, a key control strategy, aims to reduce cancer incidence through programs directed towards reducing population exposure to known causal factors. Before enacting such strategies, it is necessary to estimate the likely effect on cancer incidence if exposures to known causal factors were reduced or eliminated. The population attributable fraction (PAF) is the epidemiological measure which quantifies this potential reduction in incidence. We surveyed the literature to document and summarise the proportions of cancers across the globe attributable to modifiable causes, specifically tobacco smoke, alcohol, overweight/obesity, insufficient physical activity, solar ultraviolet (UV) radiation and dietary factors (insufficient fruit, non-starchy vegetables and fibre; red/processed meat; salt). In total, we identified 55 articles that presented PAF estimates for one or more causes. Information coverage was not uniform, with many articles reporting cancer PAFs due to overweight/obesity, alcohol and tobacco, but fewer reporting PAFs for dietary factors or solar UV radiation. At all cancer sites attributable to tobacco and alcohol, median PAFs were markedly lower for women than men. Smoking contributed to very high median PAFs (>50%) for cancers of the lung and larynx. Median PAFs for men, attributable to alcohol, were high (25-50%) for cancers of the oesophagus, oral cavity/pharynx, larynx and liver. For cancers causally associated with overweight/obesity, high median PAFs were reported for oesophageal adenocarcinoma (men 29%, women 37%), gallbladder (men 11%, women 42%) and endometrium (36%). The cancer PAF literature is growing rapidly. Repeating this survey in the future should lead to more precise estimates of the potentially preventable fractions of cancer.

Cancers in Australia in 2010 attributable to insufficient physical activity

Objectives

To estimate the proportion and numbers of cancers occurring in Australia in 2010 attributable to insufficient levels of physical activity.

Methods

We estimated the population attributable fraction (PAF) of cancers causally associated with insufficient physical activity (colon, post-menopausal breast and endometrium) using standard formulae incorporating prevalence of insufficient physical activity (<60 minutes at least 5 days/week), relative risks associated with physical activity and cancer incidence. We also estimated the proportion change in cancer incidence (potential impact fraction [PIF]) that may have occurred assuming that everyone with insufficient activity levels increased their exercise by 30 minutes/week.

Results

An estimated 1,814 cases of colon, post-menopausal breast and endometrial cancer were attributable to insufficient levels of physical activity: 707 (6.5%) colon; 971 (7.8%) post-menopausal breast; and 136 (6.0%) endometrial cancers. If those exercising below the recommended level had increased their activity level by 30 minutes/week, we estimate 314 fewer cancers (17% of those attributable to insufficient physical activity) would have occurred in 2010.

Conclusions

More than 1,500 cancers were attributable to insufficient levels of physical activity in the Australian population.

Implications

Increasing the proportion of Australians who exercise could reduce the incidence of several common cancers.

A methodologic framework to evaluate the number of cancers attributable to lifestyle and environment in Alberta

BACKGROUND

Previous research to estimate population attributable risks for cancer in Alberta has been limited. Attributable burden estimates are important for planning and implementing population-based cancer prevention strategies. This article describes a methodologic framework to estimate the number of incident cancers attributable to modifiable lifestyle and environmental risk factors in Alberta.

METHODS

We estimated population attributable risks for cancer for exposures to 24 established cancer risk factors including tobacco consumption and environmental tobacco exposure, environmental factors, infectious agents, hormone therapies, dietary intake, obesity and physical inactivity. We used risk estimates to quantify the association between individual exposures and cancer sites as well as prevalence estimates for individual exposures in Alberta to estimate the proportion of cancer in Alberta that could be attributed to each exposure. These estimations were conducted in the context of a theoretical minimum risk principle, whereby exposures corresponding to the lowest levels of population risk were used as the comparisons for alternative exposure levels.

INTE RPRETATION

We outline the main methodologic principles for the protocol used in evaluating population attributable risks for modifiable lifestyle and environmental risk factors for cancer in Alberta. The data produced by this project will provide important information concerning which known cancer risk factors are responsible for the largest proportions of cancer in Alberta and could inform future cancer prevention strategies.

Increasing the frequency of physical activity very brief advice for cancer patients. Development of an intervention using the behaviour change wheel

BACKGROUND

Being physically active has multiple benefits for cancer patients. Despite this only 23% are active to the national recommendations and 31% are completely inactive. A cancer diagnosis offers a teachable moment in which patients might be more receptive to lifestyle changes. Nurses are well placed to offer physical activity advice, however, only 9% of UK nurses involved in cancer care talk to all cancer patients about physical activity. A change in the behaviour of nurses is needed to routinely deliver physical activity advice to cancer patients. As recommended by the Medical Research Council, behavioural change interventions should be evidenced-based and use a relevant and coherent theoretical framework to stand the best chance of success.

OBJECTIVE

This paper presents a case study on the development of an intervention to improve the frequency of delivery of very brief advice (VBA) on physical activity by nurses to cancer patients, using the Behaviour Change Wheel (BCW).

METHOD

The eight composite steps outlined by the BCW guided the intervention development process. An iterative approach was taken involving key stakeholders (n = 45), with four iterations completed in total. This was not defined a priori but emerged during the development process.

RESULTS

A 60 min training intervention, delivered in either a face-to-face or online setting, with follow-up at eight weeks, was designed to improve the capability, opportunity and motivation of nurses to deliver VBA on physical activity to people living with cancer. This intervention incorporates seven behaviour change techniques of goal setting coupled with commitment; instructions on how to perform the behaviour; salience of the consequences of delivering VBA; a demonstration on how to give VBA, all delivered via a credible source with objects added to the environment to support behavioural change.

CONCLUSION

The BCW is a time consuming process, however, it provides a useful and comprehensive framework for intervention development and greater control over intervention replication and evaluation.

Effect of weight loss, with or without exercise, on body composition and sex hormones in postmenopausal women: the SHAPE-2 trial

Introduction

Physical inactivity and overweight are risk factors for postmenopausal breast cancer. The effect of physical activity may be partially mediated by concordant weight loss. We studied the effect on serum sex hormones, which are known to be associated with postmenopausal breast cancer risk, that is attributable to exercise by comparing randomly obtained equivalent weight loss by following a hypocaloric diet only or mainly by exercise.

Methods

Overweight, insufficiently active women were randomised to a diet (N = 97), mainly exercise (N = 98) or control group (N = 48). The goal of both interventions was to achieve 5–6 kg of weight loss by following a calorie-restricted diet or an intensive exercise programme combined with only a small caloric restriction. Primary outcomes after 16 weeks were serum sex hormones and sex hormone-binding globulin (SHBG). Body fat and lean mass were measured by dual-energy X-ray absorptiometry.

Results

Both the diet (−4.9 kg) and mainly exercise (−5.5 kg) groups achieved the target weight loss. Loss of body fat was significantly greater with exercise versus diet (difference −1.4 kg, P < 0.001). In the mainly exercise arm, the reduction in free testosterone was statistically significantly greater than that of the diet arm (treatment effect ratio [TER] 0.92, P = 0.043), and the results were suggestive of a difference for androstenedione (TER 0.90, P = 0.064) and SHBG (TER 1.05, P = 0.070). Compared with the control arm, beneficial effects were seen with both interventions, diet and mainly exercise, respectively, on oestradiol (TER 0.86, P = 0.025; TER 0.83, P = 0.007), free oestradiol (TER 0.80, P = 0.002; TER 0.77, P < 0.001), SHBG (TER 1.14; TER 1.21, both P < 0.001) and free testosterone (TER 0.91, P = 0.069; TER = 0.84, P = 0.001). After adjustment for changes in body fat, intervention effects attenuated or disappeared.

Conclusions

Weight loss with both interventions resulted in favourable effects on serum sex hormones, which have been shown to be associated with a decrease in postmenopausal breast cancer risk. Weight loss induced mainly by exercise additionally resulted in maintenance of lean mass, greater fitness, greater fat loss and a larger effect on (some) sex hormones. The greater fat loss likely explains the observed larger effects on sex hormones.

Trial registration

ClinicalTrials.gov identifier: NCT01511276. Registered on 12 January 2012.

Electronic supplementary material

The online version of this article (doi:10.1186/s13058-015-0633-9) contains supplementary material, which is available to authorized users.

The proportion of postmenopausal breast cancer cases in the Netherlands attributable to lifestyle-related risk factors

We aimed to estimate the proportion of Dutch postmenopausal breast cancer cases in 2010 that is attributable to lifestyle-related risk factors. We calculated population attributable fractions (PAFs) of potentially modifiable risk factors for postmenopausal breast cancer in Dutch women aged >50 in 2010. First, age-specific PAFs were calculated for each risk factor, based on their relative risks for postmenopausal breast cancer (from meta-analyses) and age-specific prevalence in the population (from national surveys) around the year 2000, assuming a latency period of 10 years. To obtain the overall PAF, age-specific PAFs were summed in a weighted manner, using the age-specific breast cancer incidence rates (2010) as weights. 95 % confidence intervals for PAF estimates were derived by Monte Carlo simulations. Of Dutch women >40 years, in 2000, 51 % were overweight/obese, 55 % physically inactive (<5 days/week 30 min activity), 75 % regularly consumed alcohol, 42 % ever smoked cigarettes and 79 % had a low-fibre intake (<3.4 g/1000 kJ/day). These factors combined had a PAF of 25.7 % (95 % CI 24.2–27.2), corresponding to 2,665 Dutch postmenopausal breast cancer cases in 2010. PAFs were 8.8 % (95 % CI 6.3–11.3) for overweight/obesity, 6.6 % (95 % CI 5.2–8.0) for alcohol consumption, 5.5 % (95 % CI 4.0–7.0) for physical inactivity, 4.6 % (95 % CI 3.3–6.0) for smoking and 3.2 % (95 % CI 1.6–4.8) for low-fibre intake. Our findings imply that modifiable risk factors are jointly responsible for approximately one out of four Dutch postmenopausal breast cancer cases. This suggests that incidence rates can be lowered substantially by living a more healthy lifestyle.

Advanced glycation end-products: a biological consequence of lifestyle contributing to cancer disparity

Low income, poor diet, obesity, and a lack of exercise are interrelated lifestyle factors that can profoundly alter our biologic make up to increase cancer risk, growth, and development. We recently reported a potential mechanistic link between carbohydrate-derived metabolites and cancer, which may provide a biologic consequence of lifestyle that can directly affect tumor biology. Advanced glycation end-products (AGE) are reactive metabolites produced as a by-product of sugar metabolism. Failure to remove these highly reactive metabolites can lead to protein damage, aberrant cell signaling, increased stress responses, and decreased genetic fidelity. Critically, AGE accumulation is also directly affected by our lifestyle choices and shows a race-specific, tumor-dependent pattern of accumulation in cancer patients. This review will discuss the contribution of AGEs to the cancer phenotype, with a particular emphasis on their biologic links with the socioeconomic and environmental risk factors that drive cancer disparity. Given the potential benefits of lifestyle changes and the potential biologic role of AGEs in promoting cancer, opportunities exist for collaborations affecting basic, translational, epidemiologic, and cancer prevention initiatives.

Cancer incidence due to excess body weight and leisure-time physical inactivity in Canada: implications for prevention

OBJECTIVE

This analysis aimed to estimate the number of incident cases of various cancers attributable to excess body weight (overweight, obesity) and leisure-time physical inactivity annually in Canada.

METHODS

The number of attributable cancers was estimated using the population attributable fraction (PAF), risk estimates from recent meta-analyses and population exposure prevalence estimates obtained from the Canadian Community Health Survey (2000). Age-sex-site-specific cancer incidence was obtained from Statistics Canada tables for the most up-to-date year with full national data, 2007. Where the evidence for association has been deemed sufficient, we estimated the number of incident cases of the following cancers attributable to obesity: colon, breast, endometrium, esophagus (adenocarcinomas), gallbladder, pancreas and kidney; and to physical inactivity: colon, breast, endometrium, prostate, lung and/or bronchus, and ovarian.

RESULTS

Overall, estimates of all cancer incidence in 2007 suggest that at least 3.5% (n=5771) and 7.9% (n=12,885) are attributed to excess body weight and physical inactivity respectively. For both risk factors the burden of disease was greater among women than among men.

CONCLUSION

Thousands of incident cases of cancer could be prevented annually in Canada as good evidence exists for effective interventions to reduce these risk factors in the population.

Physical activity as an adjuvant treatment for breast cancer; is it time for guidelines?

The question to debate is that do lifestyle interventions, in particular participation in regular Physical activity (PA), have a role in enhancing the outcome of breast cancer (BC)? Should women diagnosed with BC be encouraged to initiate and maintain a programme of PA?

Cholesterol metabolism and colorectal cancers

Colorectal cancer (CRC) is primarily a lifestyle disease of the western world. As such it can be likened to cardiovascular disease and indeed it shares many of the same risk factors. It is therefore perhaps unsurprising that cholesterol metabolism and colorectal cancer are also intricately linked. Many of the initial studies suggesting a link between dietary cholesterol, blood cholesterol levels and cholesterol lowering drugs were performed more than a decade ago. The most recent insights in this field are the result of meta-analyses, advances in pharmacogenetics and the new field of molecular pathological epidemiology. This review summarises the current evidence linking cholesterol metabolism with colorectal cancer including the suggested underlying molecular causes and the implications for colorectal cancer prevention.

Genetic Influences on Physiological and Subjective Responses to an Aerobic Exercise Session among Sedentary Adults

Objective. To determine whether genetic variants suggested by the literature to be associated with physiology and fitness phenotypes predicted differential physiological and subjective responses to a bout of aerobic exercise among inactive but otherwise healthy adults. Method. Participants completed a 30-minute submaximal aerobic exercise session. Measures of physiological and subjective responding were taken before, during, and after exercise. 14 single nucleotide polymorphisms (SNPs) that have been previously associated with various exercise phenotypes were tested for associations with physiological and subjective response to exercise phenotypes. Results. We found that two SNPs in the FTO gene (rs8044769 and rs3751812) were related to positive affect change during exercise. Two SNPs in the CREB1 gene (rs2253206 and 2360969) were related to change in temperature during exercise and with maximal oxygen capacity (VO(2) max). The SLIT2 SNP rs1379659 and the FAM5C SNP rs1935881 were associated with norepinephrine change during exercise. Finally, the OPRM1 SNP rs1799971 was related to changes in norepinephrine, lactate, and rate of perceived exertion (RPE) during exercise. Conclusion. Genetic factors influence both physiological and subjective responses to exercise. A better understanding of genetic factors underlying physiological and subjective responses to aerobic exercise has implications for development and potential tailoring of exercise interventions.