Showing papers by "Kerry S. Courneya published in 2011"

Changes in insulin resistance indicators, IGFs, and adipokines in a year-long trial of aerobic exercise in postmenopausal women

Abstract: Physical activity is a known modifiable lifestyle means for reducing postmenopausal breast cancer risk, but the biologic mechanisms are not well understood. Metabolic factors may be involved. In this study, we aimed to determine the effects of exercise on insulin resistance (IR) indicators, IGF1, and adipokines in postmenopausal women. The Alberta Physical Activity and Breast Cancer Prevention Trial was a two-armed randomized controlled trial in postmenopausal, inactive, cancer-free women. A year-long aerobic exercise intervention of 225 min/week (n=160) was compared with a control group asked to maintain usual activity levels (n=160). Baseline, 6- and 12-month serum levels of insulin, glucose, IGF1, IGF-binding protein 3 (IGFBP3), adiponectin, and leptin were assayed, and after data collection, homeostasis model assessment of IR (HOMA-IR) scores were calculated. Intention-to-treat analyses were performed using linear mixed models. The treatment effect ratio (TER) of exercisers to controls was calculated. Data were available on 308 (96.3%) women at 6 months and 310 (96.9%) women at 12 months. Across the study period, statistically significant reductions in insulin (TER=0.87, 95% confidence interval (95% CI)=0.81–0.93), HOMA-IR (TER=0.86, 95% CI=0.80–0.93), and leptin (TER=0.82, 95% CI=0.78–0.87), and an increase in the adiponectin/leptin ratio (TER=1.21, 95% CI=1.13–1.28) were observed in the exercise group compared with the control group. No significant differences were observed for glucose, IGF1, IGFBP3, adiponectin or the IGF1/IGFBP3 ratio. Previously inactive postmenopausal women who engaged in a moderate-to-vigorous intensity exercise program experienced changes in insulin, HOMA-IR, leptin, and adiponectin/leptin that might decrease the risk for postmenopausal breast cancer.

Adiposity changes after a 1-year aerobic exercise intervention among postmenopausal women: a randomized controlled trial

Abstract: Adiposity changes after a 1-year aerobic exercise intervention among postmenopausal women: a randomized controlled trial

Determinants of quality of life in adults with type 1 and type 2 diabetes

Abstract: Limited evidence exists on the determinants of quality of life (QoL) specific to adults with type 1 diabetes (T1D). Further, it appears no study has compared the determinants of QoL between T1D and type 2 diabetes (T2D) groups. The objectives of this study were to examine: (1) determinants of QoL in adults with T1D; and, (2) differences in QoL determinants between T1D and T2D groups. The Alberta Longitudinal Exercise and Diabetes Research Advancement (ALEXANDRA) study, a longitudinal study of adults with diabetes in Alberta, Canada. Adults (18 years and older) with T1D (N = 490) and T2D (N = 1,147) provided information on demographics (gender, marital status, education, and annual income), personality (activity trait), medical factors (diabetes duration, insulin use, number of comorbidities, and body mass index), lifestyle behaviors (smoking habits, physical activity, and diet), health-related quality of life (HRQL) and life satisfaction. Multiple regression models identified determinants of HRQL and life satisfaction in adults with T1D. These determinants were compared with determinants for T2D adults reported in a previous study from this population data set. Factors significantly associated with HRQL and life satisfaction in either T1D or T2D groups were further tested for interaction with diabetes type. In adults with T1D, higher activity trait (personality) score (β = 0.28, p < 0.01), fewer comorbidities (β = - 0.27, p < 0.01), lower body mass index (BMI)(β = - 0.12, p < 0.01), being a non-smoker (β = - 0.14, p < 0.01), and higher physical activity levels (β = 0.16, p < 0.01) were associated with higher HRQL. Having a partner (β = 0.11, p < 0.05), high annual income (β = 0.16, p < 0.01), and high activity trait (personality) score (β = 0.27, p < 0.01) were significantly associated with higher life satisfaction. There was a significant age × diabetes type interaction for HRQL. The T2D group had a stronger positive relationship between advancing age and HRQL compared to the T1D group. No interaction was significant for life satisfaction. Health services should target medical and lifestyle factors and provide support for T1D adults to increase their QoL. Additional social support for socioeconomically disadvantaged individuals living with this disease may be warranted. Health practitioners should also be aware that age has different effects on QoL between T1D and T2D adults.

Case–Control Study of the Metabolic Syndrome and Metabolic Risk Factors for Endometrial Cancer

Abstract: Background: Metabolic syndrome may predict endometrial cancer risk better than diabetes, hypertension, dyslipidemia, dysglycemia, or weight alone, but few studies have examined this issue. Methods: We conducted a population-based case–control study in Alberta, Canada (2002–2006) that included 515 incident endometrial cancer cases and 962 frequency age-matched controls. Data were collected through in-person interviews, anthropometric measurements, and 8-hour fasting bloods drawn either pre- or postsurgery. Bloods were analyzed using quantitative colorimetric or absorbance-based assays (ELISA), specific to metabolic syndrome markers. Metabolic syndrome was defined using harmonized guidelines requiring presence of ≥3 of the following risk factors: waist circumference ≥88 cm, triglycerides ≥150 mg/dL, high-density lipoprotein cholesterol <50 mg/dL, treatment of previously diagnosed hypertension, and fasting blood glucose ≥100 mg/dL. OR and 95% CIs for endometrial cancer risk with presence of metabolic syndrome and individual metabolic syndrome components were estimated using logistic regression analysis. Results: Metabolic syndrome was significantly more prevalent among cases (62%) than controls (38%). A statistically significant increased risk for endometrial cancer was observed for metabolic syndrome (OR = 1.53; 95% CI: 1.17–2.00), as well as for some of the individual components of metabolic syndrome including waist circumference ≥88 cm (OR = 1.57; 95% CI: 1.18–2.08), hypertension (OR = 1.57; 95% CI: 1.18–2.09), and fasting blood glucose ≥100 mg/dL (OR = 1.31; 95% CI: 1.03–1.67). Some evidence for effect modification by menopausal status and body mass index was also found. Conclusion: Metabolic syndrome is clearly associated with increased endometrial cancer risk. Impact: Targeting the entire metabolic syndrome may optimize endometrial cancer risk reduction. Cancer Epidemiol Biomarkers Prev; 20(11); 2384–95. ©2011 AACR .

Physical activity and cancer

Abstract: Introduction. Physical Activity and Cancer Prevention: Breast cancer prevention. Genitourinary cancer prevention . Gastrointestinal cancer prevention. Lung cancer prevention. Hematologic cancer prevention. Gynecologic cancer prevention.- Physical Activity and Cancer Survivorship: Breast cancer survivorship. Genitourinary cancer survivorship. Gastrointestinal cancer survivorship. Lung cancer survivorship. Hematologic cancer survivorship. Gynecologic cancer survivorship.- Special Topics: Pediatric cancer survivorship. Palliative cancer care. Physical activity motivation and cancer survivorship.

Reduced barriers mediated physical activity maintenance among breast cancer survivors.

Abstract: To better understand mechanisms of physical activity (PA) behavior change in breast cancer survivors, we examined mediation of a successful PA behavior change intervention by social cognitive theory (SCT) constructs. Our exploratory study randomized 41 breast cancer survivors to receive the 3-month intervention (INT) or usual care (UC). We used the Freedman and Schatzkin approach to examine mediation of intervention effect on PA 3 months postintervention by changes in SCT constructs from baseline to immediately postintervention. Compared with UC, the INT group reported lower barriers interference (mean difference = −7.8, 95% CI [−15.1, −0.4], d = −0.67, p = .04) and greater PA enjoyment (mean difference = 0.7, 95% CI [0, 1.5], d = 0.61, p = .06). Barriers interference mediated 39% (p = .004) of the intervention effect on PA 3 months postintervention. PA enjoyment was not a significant mediator. Reducing barriers to PA partially explained our intervention effect.

Physical activity type and intensity among rural breast cancer survivors: patterns and associations with fatigue and depressive symptoms

Abstract: Introduction Our study aims were to describe physical activity patterns and associations with fatigue and depressive symptoms among rural breast cancer survivors.

Physical activity and health-related quality of life in young adult cancer survivors: a Canadian provincial survey

Abstract: Objectives Physical activity (PA) improves health-related quality of life (HRQL) in several cancer survivor groups but no studies have focused on young adult cancer survivors (YACS). This study determined the prevalence of PA in YACS and examined dose-response associations with HRQL.

Interest and preferences for exercise counselling and programming among Norwegian cancer survivors.

Abstract: To be able to make suitable exercise intervention programmes for cancer survivors, we need more information about exercise preferences. The primary aim of the study was to investigate the interest and preferences for exercise among Norwegian cancer survivors. A secondary aim was to identify demographic and medical characteristics associated with interest in exercise counselling. A questionnaire was completed by 1284 cancer survivors. Overall, 76% of participants were interested or maybe interested in receiving exercise counselling at some point during their cancer experience. Logistic regression analyses indicated that the interest in exercise counselling in men was associated with younger age, presence of comorbidity and having received chemotherapy. In women, the interest was associated with younger age, higher education and change in physical activity level. The participants preferred face-to-face exercise counselling with an exercise specialist from a cancer centre, at a hospital, immediately after treatment. Most cancer survivors were interested in an exercise programme, walking as activity, at moderate intensity and they wanted to start immediately after treatment. The knowledge from this study can contribute to make suitable physical rehabilitation available to cancer patients in the future.

Associations Between Physical Activity and Quality of Life in a Population-Based Sample of Kidney Cancer Survivors

Abstract: Background: Physical activity (PA) improves quality of life (QoL) in several cancer survivor groups, but no study to date has focused on kidney cancer survivors (KCS). The purpose of this study was to estimate the prevalence of PA in KCS and determine any associations with QoL. Methods: All 1,985 KCS diagnosed between 1996 and 2010 identified through a Canadian provincial Registry were mailed a survey that consisted of the Godin Leisure Time Exercise Questionnaire and several Functional Assessment of Cancer Therapy QoL scales. Standard demographic and medical variables were also reported. Results: Completed surveys were received from 703 (43%) of the 1,654 KCS that received the survey. Over half (56.3%) were completely sedentary (CS), 17.6% were insufficiently active, 11.9% were active within public health guidelines, and 14.1% exceeded public health guidelines. After adjustment for key demographic and medical covariates, analyses of covariance indicated a dose–response association between PA and most QoL outcomes from CS to within guidelines (WG) with no further improvements for exceeding guidelines. For the primary QoL outcome of patient-reported physical functioning, the overall difference between CS and WG was 8.6 points (95% CI: 4.2–12.9, P < 0.001) which exceeds the minimally important difference of 5.0 points for this scale. Few associations were moderated by demographic or medical variables. Conclusion: Over half of KCS are CS; however, even some PA may be beneficial for QoL. Impact: PA is a modifiable lifestyle factor that may have implications for QoL and disease outcomes in KCS. Cancer Epidemiol Biomarkers Prev; 20(5); 859–68. ©2011 AACR .

Exercise behavior in cancer survivors and associated factors

Abstract: Introduction Physical activity is an important component in promoting a healthy life style in cancer survivors. We estimated the proportion of cancer survivors who are physically active, defined as meeting public health exercise guidelines, and changes in level of physical activity (LPA) from before diagnosis to after treatment. We also identified medical and demographic factors associated with LPA and its changes.

Predictors of physical activity in adults with type 2 diabetes.

Abstract: Objectives To determine demographic, medical, social cognitive, and environmental predictors of aerobic physical activity and resistance training in a population sample of adults with type 2 diabetes. Methods Two hundred forty-four (244) participants completed questionnaires with a 3-month follow-up. Multiple and logistic regression models examined predictors of aerobic activity and resistance training. Results Several factors were associated with higher levels of both aerobic physical activity and resistance training; self-efficacy was the strongest predictor for both modes of activity. Conclusions The findings can guide physical activity promotion interventions and programs for this population, profiling those who are least active.

Associations of overall and abdominal adiposity with area and volumetric mammographic measures among postmenopausal women

Abstract: Whereas mammographic density and adiposity are positively associated with postmenopausal breast cancer risk, they are inversely associated with one another. To examine the association between these two risk factors, a secondary analysis of data from a randomized controlled trial of a year-long aerobic exercise intervention was done. Participants were 302 postmenopausal women aged 50-74 years. Dense fibroglandular and nondense fatty tissue were measured from mammograms using computer-assisted thresholding software for area measurements and a technique relying on the calibration of mammography machines with a tissue-equivalent phantom for volumetric measurements. Adiposity was measured by anthropometry (body mass index, waist circumference), whole-body dual x-ray absorptiometry scans (body fat) and computed tomography scans (abdominal adiposity). Correlations were estimated between and within women, the latter representing the association between the 1-year change in adiposity and mammographic measures. Adiposity was correlated with nondense area and volume (0.50 ≤ r ≤ 0.66 between women; 0.18 ≤ r ≤ 0.46 within women). Between women, adiposity was correlated with dense area and volume (-0.12 ≤ r ≤ -0.30) and with percent dense area and volume (-0.28 ≤ r ≤ -0.48). Because measurements made with scans explained at most only 3% more of the variation in absolute or percent density beyond that explained by anthropometric measurements, anthropometric measurements are likely sufficient for adjustment of the association between mammographic density and breast cancer risk. Adiposity is associated with breast fatty tissue and possibly weakly inversely associated with fibroglandular tissue.

Determinants of quality of life in type 2 diabetes population: the inclusion of personality

Abstract: Objective The identification of factors that affect quality of life (QoL) is crucial to ameliorate the increasing burden of diabetes. This study tested a multi-dimensional model that consisted of factors across three domains (personal, medical, and lifestyle factors) to understand determinants of QoL in adults with type 2 diabetes.

Efficacy of a referral and physical activity program for survivors of prostate cancer [ENGAGE]: Rationale and design for a cluster randomised controlled trial

Abstract: Despite evidence that physical activity improves the health and well-being of prostate cancer survivors, many men do not engage in sufficient levels of activity. The primary aim of this study (ENGAGE) is to determine the efficacy of a referral and physical activity program among survivors of prostate cancer, in terms of increasing participation in physical activity. Secondary aims are to determine the effects of the physical activity program on psychological well-being, quality of life and objective physical functioning. The influence of individual and environmental mediators on participation in physical activity will also be determined. This study is a cluster randomised controlled trial. Clinicians of prostate cancer survivors will be randomised into either the intervention or control condition. Clinicians in the intervention condition will refer eligible patients (n = 110) to participate in an exercise program, comprising 12 weeks of supervised exercise sessions and unsupervised physical activity. Clinicians allocated to the control condition will provide usual care to eligible patients (n = 110), which does not involve the recommendation of the physical activity program. Participants will be assessed at baseline, 12 weeks, 6 months, and 12 months on physical activity, quality of life, anxiety, depression, self-efficacy, outcome expectations, goals, and socio-structural factors. The findings of this study have implications for clinicians and patients with different cancer types or other chronic health conditions. It will contribute to our understanding on the potential impact of clinicians promoting physical activity to patients and the long term health benefits of participating in physical activity programs. Australia and New Zealand Clinical Trials Register (ANZCTR): ACTRN12610000609055 Deakin University Human Research Ethics Approval 2011-085

Case-Control Study of Dietary Patterns and Endometrial Cancer Risk

Abstract: Dietary patterns, rather than intakes of specific foods or nutrients, may influence risk of endometrial cancer (EC). This population-based case-control study in Canada (2002-2006) included incident EC cases (n = 506) from the Alberta Cancer Registry and controls frequency age-matched to cases (n = 981). Past-year dietary patterns were defined using factor analysis of food frequency questionnaire data. Logistic regression was used to estimate EC risk within quartiles of dietary patterns. Three patterns (sweets, meat, plants) explained 23% of the variance in the dietary data. In multivariable models, EC risk was significantly reduced by 30% for women in the highest quartile of the healthier plants pattern (OR = 0.70, 95% CI 0.50-0.98, P trend = 0.02). When stratified by body mass index (BMI; kg/m(2)), risk was further reduced among overweight or obese women with a BMI ≥25 (OR = 0.57, 95% CI 0.39-0.83; P trend = 0.004). EC was not associated with the less healthy sweets and meat patterns. However, risk was modestly, but not significantly, elevated for higher intakes of the meat pattern among overweight or obese women. A mostly plant-based dietary pattern may reduce EC risk. Recommendations for risk reduction should focus on maintaining a healthy weight and the role of diet should be studied further.

Associations between mammographic density and serum and dietary cholesterol.

Abstract: Although high mammographic density is a risk factor for postmenopausal breast cancer, its etiology remains unclear. We examined whether serum and dietary cholesterol, which increase breast cancer risk and are involved in endogenous estrogen formation, were associated with increased mammographic density. We conducted a cross-sectional analysis of 302 healthy, sedentary postmenopausal women, aged 50–74 years, enrolled in the Alberta Physical Activity and Breast Cancer Prevention Trial between 2003 and 2006. In multiple linear regression models, no significant associations were observed between serum lipids and percent density or dense tissue area (Percent density: b (change in square root percent density per unit change in cholesterol level) = −0.06 (95%CI = −0.26 to 0.13); b = 0.06 (95%CI = −0.48 to 0.61); and b = −0.11 (95%CI = −0.33 to 0.10) for total cholesterol, high-, and low-density lipoprotein, respectively; similar results found for dense area). Alcohol consumption modified the association between triglycerides and percent density (>1 drink/day: b = −0.94 (95%CI = −1.79 to −0.10); ≤1 drink/day: b = 0.19 (95%CI = −0.12 to 0.50); and no alcohol consumption: b = 0.15 (95%CI = −0.44 to 0.73). We found no evidence indicating any association between dietary and serum cholesterol levels and mammographic density.

Risk of endometrial cancer in relation to individual nutrients from diet and supplements.

Abstract: Objective Intake of nutrients may influence the risk of endometrial cancer (EC). We aimed to estimate the association of intake of individual nutrients from food and from food plus supplements with EC occurrence. Design A population-based case-control study conducted in Canada (2002-2006). Setting Nutrient intakes from food and supplements were assessed using an FFQ. Logistic regression was used to estimate EC risk within quartile levels of nutrient intakes. Subjects Incident EC cases (n 506) were identified from the Alberta Cancer Registry, and population controls were frequency- and age-matched to cases (n 981). Results There existed little evidence of an association with EC for the majority of macronutrients and micronutrients examined. We observed a statistically significant increased risk associated with the highest, compared with the lowest, quartile of intake of dietary cholesterol (multivariable-adjusted OR = 1·51, 95 % CI 1·08, 2·11; P for trend = 0·02). Age-adjusted risk at the highest level of intake was significantly reduced for Ca from food sources (OR = 0·73, 95 % CI 0·54, 0·99) but was attenuated in the multivariable model (OR = 0·82, 95 % CI 0·59, 1·13). When intake from supplements was included in Ca intake, risk was significantly reduced by 28 % with higher Ca (multivariable-adjusted OR = 0·72, 95 % CI 0·51, 0·99, P for trend = 0·04). We also observed unexpected increased risks at limited levels of intakes of dietary soluble fibre, vitamin C, thiamin, vitamin B6 and lutein/zeaxanthin, with no evidence for linear trend. Conclusions The results of our study suggest a positive association between dietary cholesterol and EC risk and an inverse association with Ca intake from food sources and from food plus supplements.

Mediators and moderators of the effects of a year-long exercise intervention on endogenous sex hormones in postmenopausal women

Abstract: Objective To identify factors that mediate or moderate the effects of exercise on postmenopausal sex hormone concentrations.