Physical activity and postmenopausal breast cancer: proposed biologic mechanisms and areas for future research

Physical Exercise Positively Influences Breast Cancer Evolution

Breast cancer is one of the most commonly diagnosed types of cancer in women. Its pathogenesis involves genetic, hormonal, and environmental factors. A large body of evidence indicates that physical activity has positive effects on every aspect of breast cancer evolution, including prevention, medical treatment, and aftercare clinical settings. Thus, different types of exercise can influence the prevention and progression of the disease through several common mechanisms, such as reduction of insulin resistance and improvement of immunity and cardiovascular function. Furthermore, acute and chronic symptoms of breast cancer, such as cachexia, muscle mass loss, fatigue, cardiotoxicity, weight gain, hormone alterations, bone loss, and psychologic adverse effects, may all be favorably influenced by regular exercise. We review the relation of intensity and duration of exercise with potential pathophysiologic pathways, including obesity-related hormones and sex steroid hormone production, oxidative stress, epigenetic alterations such as DNA hypomethylation, and changes in telomere length, within the context of the beneficial effects of exercise. The potential role of exercise in reducing the intensity of the adverse effects that result from breast cancer and anticancer treatment is also discussed.

Breast cancer and exercise: The role of adiposity and immune markers

Currently, breast cancer accounts for a quarter of all cancers and 15% of cancer-specific deaths amongst females. The global occurrence of breast cancer has increased in the last decade whilst the mortality rate has decreased. Exercise can be beneficial to breast cancer patients through changes in adiposity and immune responses. Even though there is some evidence supporting the improvement of fat metabolism and immune function after an exercise program in breast cancer, randomized controlled studies are limited and require further comprehensive analysis in this population group. Herein, we identify the known effects of exercise programs on adiposity and immunological markers which can improve breast cancer outcomes.

Epidemiological trends of hormone-related cancers in Slovenia

The incidence of hormone-related cancers tends to be higher in the developed world than in other countries. In Slovenia, six hormone-related cancers (breast, ovarian, endometrial, prostate, testicular, and thyroid) account for a quarter of all cancers. Their incidence goes up each year, breast and prostate cancer in particular. The age at diagnosis is not decreasing for any of the analysed cancer types. The risk of breast cancer is higher in the western part of the country, but no differences in geographical distribution have been observed for other hormone-related cancers. Furthermore, areas polluted with endocrine-disrupting chemicals that affect hormone balance such as PCBs, dioxins, heavy metals, and pesticides, do not seem to involve a greater cancer risk. We know little about how many cancers can be associated with endocrine disruptors, as there are too few reliable exposure studies to support an association.

Effects of Exercise on Insulin, IGF Axis, Adipocytokines, and Inflammatory Markers in Breast Cancer Survivors: A Systematic Review and Meta-analysis

Background: Insulin, IGF axis, adiponectin, and inflammatory markers are associated with breast cancer. Given that physical activity improves prognosis of breast cancer survivors, we investigated the effects of exercise on these markers as potential mediators between physical activity and breast cancer.Methods: PubMed, EMBASE, CENTRAL, CINAHL, and SportDiscus were searched up to December 3, 2015, to identify randomized controlled trials (RCT) that investigated the effect of exercise on insulin, IGF axis, and cytokines in breast cancer survivors. Weighted mean difference (WMD) was calculated using either fixed- or random-effects models on the basis of the heterogeneity of the studies.Results: A total of 18 studies involving 681 breast cancer survivors were included, and these numbers were reduced for individual biomarker analyses. We found that exercise significantly reduced fasting insulin levels [WMD, -3.46 μU/mL; 95% confidence interval (CI), -5.97 to -0.95; P = 0.007]. Furthermore, potentially meaningful but statistically nonsignificant changes were observed in insulin resistance (WMD, -0.73; 95% CI, -0.54 to 0.13; P = 0.23), adiponectin (WMD, 1.17 μg/mL; 95% CI, -0.87 to 3.20; P = 0.26), and C-reactive protein (WMD, -1.10 mg/L; 95% CI, -2.39 to 0.20; P = 0.10). Subgroup analyses showed that fasting insulin levels were significantly more impacted in studies in which intervention participants experienced a weight reduction (WMD, -7.10 μU/mL; 95% CI, -10.31 to -3.90; P < 0.001).Conclusions: Exercise reduces fasting insulin levels in breast cancer survivors. This may be due to exercise-induced reductions in body weight.Impact: Practitioners and clinicians may better help breast cancer prognosis be improved through exercise, anticipating physiological effects on cancer. Cancer Epidemiol Biomarkers Prev; 26(3); 355-65. ©2016 AACR.

Long-term effects of a weight loss intervention with or without exercise component in postmenopausal women: A randomized trial

The aim of this study was to determine the long-term effects of a weight loss intervention with or without an exercise component on body weight and physical activity. Women were randomized to diet (n = 97) or exercise (N = 98) for 16 weeks. During the intervention, both groups had achieved the set goal of 5-6 kg weight loss. All women were re-contacted twelve months after study cessation for follow-up where body weight and physical activity were measured (PASE questionnaire and ActiGraph accelerometer). At follow-up, body weight and physical activity (measured by the PASE questionnaire and accelerometer) were measured again. At follow-up, both mainly exercise (- 4.3 kg, p < 0.001) and diet (- 3.4 kg, p < 0.001) showed significantly reduced body weight compared to baseline. Both the mainly exercise and diet group were significantly more physically active at one year follow-up compared to baseline (PASE: + 33%, p < 0.001 and + 12%, p = 0.040, respectively; ActiGraph: + 16%, p = 0.012. and + 2.2%, p = 0.695 moderate-to-vigorous activity, respectively). Moreover, the increase in physical activity was statistically significantly when comparing exercise to diet (+ 0.6%, p = 0.035). ActiGraph data also showed significantly less sedentary time in mainly exercise group compared to baseline (- 2.1%, p = 0.018) and when comparing exercise to diet (- 1.8%, p = 0.023). No significant within group differences were found for the diet group. This study shows largely sustained weight loss one year after completing a weight loss program with and without exercise in overweight postmenopausal women. Although the mainly exercise group maintained more physically active compared to the diet group, maintenance of weight loss did not differ between groups.

Behavioral risk factors of breast cancer in Bangui of Central African Republic: A retrospective case-control study

Breast cancer is recognized as a major public health problem in developing countries; however, there is very little evidence of behavioral factors associated with breast cancer risk. This study was conducted to identify lifestyles as risk factors for breast cancer among Central African women. A case-control study was conducted with 174 cases confirmed histologically by the pathology unit of the National Laboratory and 348 age-matched controls. Data collection tools included a questionnaire with interviews and medical records of patients. Data were analyzed using SPSS software version 20. Odd ratio (OR) and 95% confidence intervals (95% CI) were obtained by unconditional logistic regression. In total, 522 women were studied with a mean age of 45.8 (SD = 13.4) years. By unconditional logistic regression model, women with breast cancer were more likely to have attained illiterate and elementary education level [11.23 (95% CI, 4.65-27.14) and 2.40 (95% CI, 1.15-4.99)], married [2.09 (95% CI, 1.18-3.71)], positive family history [2.31 (95% CI, 1.36-3.91)], radiation exposure [8.21 (95% CI, 5.04-13.38)], consumption charcuterie [10.82 (95% CI, 2.39-48.90)], fresh fish consumption [4.26 (95% CI, 1.56-11.65)], groundnut consumption [6.46 (95% CI, 2.57-16.27)], soybean consumption [16.74 (95% CI, 8.03-39.84)], alcohol [2.53 (95% CI, 1.39-4.60)], habit of keeping money in bras[3.57 (95% CI, 2.24-5.69)], overweight [5.36 (95% CI, 4.46-24.57)] and obesity [3.11(95% CI, 2.39-20.42)]. However, decreased risk of breast cancer was associated with being employed [0.32 (95% CI, 0.19-0.56)], urban residence [0.16 (95% CI, 0.07-0.37)], groundnut oil consumption [0.05 (95% CI, 0.02-0.14)], wine consumption [0.16 (95% CI, 0.09-0.26)], non habit of keeping cell phone in bras [0.56 (95% CI, 0.35-0.89)] and physical activity [0.71(95% CI, 0.14-0.84)]. The study showed that little or no education, marriage, positive family history of cancer, radiation exposure, charcuterie, fresh fish, groundnut, soybean, alcohol, habit of keeping money in bras, overweight and obesity were associated with breast cancer risk among Central African women living in Bangui. Women living in Bangui should be more cautious on the behavioral risk associated with breast cancer.

Association of Active and Sedentary Behaviors with Postmenopausal Estrogen Metabolism

PURPOSE

Physical activity may reduce endogenous estrogens, but few studies have assessed effects on estrogen metabolism and none have evaluated sedentary behavior in relation to estrogen metabolism. We assessed relationships between accelerometer-measured physical activity and sedentary behavior and 15 urinary estrogens and estrogen metabolites (EM) among postmenopausal controls from a population-based breast cancer case-control study conducted in Poland (2000-2003).

METHODS

Postmenopausal women (N = 542) were ages 40 to 72 yr and not currently using hormone therapy. Accelerometers, worn for 7 d, were used to derive measures of average activity (counts per day) and sedentary behavior (<100 counts per minute per day). Estrogen metabolites were measured in 12-h urine samples using liquid chromatography-tandem mass spectrometry. Estrogen metabolites were analyzed individually, in metabolic pathways (C-2, -4, or -16), and as ratios relative to parent estrogens. Geometric means of estrogen metabolites by tertiles of accelerometer-measures, adjusted for age and body mass, were computed using linear models.

RESULTS

High activity was associated with lower levels of estrone and estradiol (P trend = 0.01), whereas increased sedentary time was positively associated with these parent estrogens (P trend = 0.04). Inverse associations were observed between high activity and 2-methoxyestradiol, 4-methoxyestradiol, 17-epiestriol, and 16-epiestriol (P trend = 0.03). Sedentary time was positively associated with methylated catechols in the 2- and 4-hydroxylation pathways (P trend ≤ 0.04). Women in the highest tertile of activity had increased hydroxylation at the C-2, -4, and -16 sites relative to parent estrogens (P trend ≤ 0.02), whereas increased sedentary time was associated with a lower 16-pathway/parent estrogen ratio (P trend = 0.01).

CONCLUSIONS

Higher activity was associated with lower urinary estrogens, possibly through increased estrogen hydroxylation and subsequent metabolism, whereas sedentary behavior may reduce metabolism.

Yoga for improving health-related quality of life, mental health and cancer-related symptoms in women diagnosed with breast cancer

BACKGROUND

Breast cancer is the cancer most frequently diagnosed in women worldwide. Even though survival rates are continually increasing, breast cancer is often associated with long-term psychological distress, chronic pain, fatigue and impaired quality of life. Yoga comprises advice for an ethical lifestyle, spiritual practice, physical activity, breathing exercises and meditation. It is a complementary therapy that is commonly recommended for breast cancer-related impairments and has been shown to improve physical and mental health in people with different cancer types.

OBJECTIVES

To assess effects of yoga on health-related quality of life, mental health and cancer-related symptoms among women with a diagnosis of breast cancer who are receiving active treatment or have completed treatment.

SEARCH METHODS

We searched the Cochrane Breast Cancer Specialised Register, MEDLINE (via PubMed), Embase, the Cochrane Central Register of Controlled Trials (CENTRAL; 2016, Issue 1), Indexing of Indian Medical Journals (IndMED), the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) search portal and Clinicaltrials.gov on 29 January 2016. We also searched reference lists of identified relevant trials or reviews, as well as conference proceedings of the International Congress on Complementary Medicine Research (ICCMR), the European Congress for Integrative Medicine (ECIM) and the American Society of Clinical Oncology (ASCO). We applied no language restrictions.

SELECTION CRITERIA

Randomised controlled trials were eligible when they (1) compared yoga interventions versus no therapy or versus any other active therapy in women with a diagnosis of non-metastatic or metastatic breast cancer, and (2) assessed at least one of the primary outcomes on patient-reported instruments, including health-related quality of life, depression, anxiety, fatigue or sleep disturbances.

DATA COLLECTION AND ANALYSIS

Two review authors independently collected data on methods and results. We expressed outcomes as standardised mean differences (SMDs) with 95% confidence intervals (CIs) and conducted random-effects model meta-analyses. We assessed potential risk of publication bias through visual analysis of funnel plot symmetry and heterogeneity between studies by using the Chi² test and the I² statistic. We conducted subgroup analyses for current treatment status, time since diagnosis, stage of cancer and type of yoga intervention.

MAIN RESULTS

We included 24 studies with a total of 2166 participants, 23 of which provided data for meta-analysis. Thirteen studies had low risk of selection bias, five studies reported adequate blinding of outcome assessment and 15 studies had low risk of attrition bias.Seventeen studies that compared yoga versus no therapy provided moderate-quality evidence showing that yoga improved health-related quality of life (pooled SMD 0.22, 95% CI 0.04 to 0.40; 10 studies, 675 participants), reduced fatigue (pooled SMD -0.48, 95% CI -0.75 to -0.20; 11 studies, 883 participants) and reduced sleep disturbances in the short term (pooled SMD -0.25, 95% CI -0.40 to -0.09; six studies, 657 participants). The funnel plot for health-related quality of life was asymmetrical, favouring no therapy, and the funnel plot for fatigue was roughly symmetrical. This hints at overall low risk of publication bias. Yoga did not appear to reduce depression (pooled SMD -0.13, 95% CI -0.31 to 0.05; seven studies, 496 participants; low-quality evidence) or anxiety (pooled SMD -0.53, 95% CI -1.10 to 0.04; six studies, 346 participants; very low-quality evidence) in the short term and had no medium-term effects on health-related quality of life (pooled SMD 0.10, 95% CI -0.23 to 0.42; two studies, 146 participants; low-quality evidence) or fatigue (pooled SMD -0.04, 95% CI -0.36 to 0.29; two studies, 146 participants; low-quality evidence). Investigators reported no serious adverse events.Four studies that compared yoga versus psychosocial/educational interventions provided moderate-quality evidence indicating that yoga can reduce depression (pooled SMD -2.29, 95% CI -3.97 to -0.61; four studies, 226 participants), anxiety (pooled SMD -2.21, 95% CI -3.90 to -0.52; three studies, 195 participants) and fatigue (pooled SMD -0.90, 95% CI -1.31 to -0.50; two studies, 106 participants) in the short term. Very low-quality evidence showed no short-term effects on health-related quality of life (pooled SMD 0.81, 95% CI -0.50 to 2.12; two studies, 153 participants) or sleep disturbances (pooled SMD -0.21, 95% CI -0.76 to 0.34; two studies, 119 participants). No trial adequately reported safety-related data.Three studies that compared yoga versus exercise presented very low-quality evidence showing no short-term effects on health-related quality of life (pooled SMD -0.04, 95% CI -0.30 to 0.23; three studies, 233 participants) or fatigue (pooled SMD -0.21, 95% CI -0.66 to 0.25; three studies, 233 participants); no trial provided safety-related data.

AUTHORS' CONCLUSIONS

Moderate-quality evidence supports the recommendation of yoga as a supportive intervention for improving health-related quality of life and reducing fatigue and sleep disturbances when compared with no therapy, as well as for reducing depression, anxiety and fatigue, when compared with psychosocial/educational interventions. Very low-quality evidence suggests that yoga might be as effective as other exercise interventions and might be used as an alternative to other exercise programmes.

Accounting for individualized competing mortality risks in estimating postmenopausal breast cancer risk

PURPOSE

Accurate risk assessment is necessary for decision-making around breast cancer prevention. We aimed to develop a breast cancer prediction model for postmenopausal women that would take into account their individualized competing risk of non-breast cancer death.

METHODS

We included 73,066 women who completed the 2004 Nurses' Health Study (NHS) questionnaire (all ≥57 years) and followed participants until May 2014. We considered 17 breast cancer risk factors (health behaviors, demographics, family history, reproductive factors) and 7 risk factors for non-breast cancer death (comorbidities, functional dependency) and mammography use. We used competing risk regression to identify factors independently associated with breast cancer. We validated the final model by examining calibration (expected-to-observed ratio of breast cancer incidence, E/O) and discrimination (c-statistic) using 74,887 subjects from the Women's Health Initiative Extension Study (WHI-ES; all were ≥55 years and followed for 5 years).

RESULTS

Within 5 years, 1.8 % of NHS participants were diagnosed with breast cancer (vs. 2.0 % in WHI-ES, p = 0.02), and 6.6 % experienced non-breast cancer death (vs. 5.2 % in WHI-ES, p < 0.001). Using a model selection procedure which incorporated the Akaike Information Criterion, c-statistic, statistical significance, and clinical judgement, our final model included 9 breast cancer risk factors, 5 comorbidities, functional dependency, and mammography use. The model's c-statistic was 0.61 (95 % CI [0.60-0.63]) in NHS and 0.57 (0.55-0.58) in WHI-ES. On average, our model under predicted breast cancer in WHI-ES (E/O 0.92 [0.88-0.97]).

CONCLUSIONS

We developed a novel prediction model that factors in postmenopausal women's individualized competing risks of non-breast cancer death when estimating breast cancer risk.

Effects of exercise on markers of oxidative stress: an Ancillary analysis of the Alberta Physical Activity and Breast Cancer Prevention Trial

BACKGROUND

Oxidative stress may contribute to cancer aetiology through several mechanisms involving damage to DNA, proteins and lipids leading to genetic mutations and genomic instability. The objective of this study was to determine the effects of aerobic exercise on markers of oxidative damage and antioxidant enzymes in postmenopausal women.

METHODS

The Alberta Physical Activity and Breast Cancer Prevention Trial (ALPHA) was a two-centre, two-armed randomised trial of 320 inactive, healthy, postmenopausal women aged 50-74 years. Participants were randomly assigned to a year-long exercise intervention (225 min/week) or a control group while being asked to maintain a normal diet. Fasting blood samples were obtained and plasma concentrations of two oxidative damage markers (8-hydroxy-2'-deoxyguanosine (8-OHdG) and 8-isoprostaglandin F2α (8-Iso-PGF2α)) and two antioxidant enzymes (superoxide dismutase and catalase) were measured at baseline, 6 months and 12 months. Intention-to-treat (ITT) and per-protocol analyses were performed using linear mixed models adjusted for baseline biomarker concentrations. A further exercise adherence analysis, based on mean minutes of exercise per week, was also performed.

RESULTS

In the ITT and per-protocol analyses, the exercise intervention did not have any statistically significant effect on either oxidative damage biomarkers or antioxidant enzyme activity.

CONCLUSIONS

A year-long aerobic exercise intervention did not have a significant impact on oxidative stress in healthy, postmenopausal women.

TRIAL REGISTRATION NUMBER

NCT00522262.

Associated factors with mammographic changes in women undergoing breast cancer screening

Objective:

To evaluate association of sociodemographic, anthropometric, and epidemiological factors with result of mammogram in women undergoing breast cancer screening.

Methods:

This is a cross-sectional study with data obtained through interviews, anthropometric measurements, and mammography of 600 women aged 40 to 69 years at the Preventive Medicine Department of Hospital de Câncer de Barretos, Brazil, in 2014. The results of these examinations in the BI-RADS categories 1 and 2 were grouped and classified in this study as normal mammogram outcome, and those of BI-RADS categories 3, 4A, 4B, 4C, and 5 were grouped and classified as altered mammogram outcome. The statistical analysis included the Student's t-test to compare means, as well as odds ratios (OR), with their corresponding 95% confidence intervals (95%CI), to verify an association by means of the multivariate analysis.

Results:

Of 600 women evaluated, 45% belonged to the age group of 40–49 years-old and 60.2% were classified as BI-RADS category 2. The multivariate analysis showed that women with blood hypertension (OR: 2.64; 95%CI: 1.07–6.49; p<0.05) were more likely to present changes in the mammography, while physical activity was associated with lower chances (OR: 0.30; 95%CI: 0.11–0.81; p<0.05).

Conclusion:

Hypertensive women undergoing screening mammography are more likely to present mammographic changes, whereas women practicing physical activity have lower chances (70%) of presenting changes in the breast compared with sedentary individuals.

Vigorous physical activity and risk of breast cancer in the African American breast cancer epidemiology and risk consortium

The relationship between physical activity and breast cancer risk has been extensively studied among women of European descent, with most studies reporting inverse associations. However, data on American women of African ancestry (AA) and by tumor subtypes are sparse. Thus, we examined associations of vigorous exercise and breast cancer risk overall, and by estrogen receptor (ER) status, in the African American Breast Cancer Epidemiology and Risk Consortium. We pooled data from four large studies on 2482 ER+ cases, 1374 ER- cases, and 16,959 controls. Multivariable logistic regression was used to compute odds ratios (OR) and 95 % confidence intervals (CI) for the risk of breast cancer overall, and polytomous logistic regression was used to model the risk of ER+ and ER- cancer. Recent vigorous exercise was associated with a statistically significant, modestly decreased risk for breast cancer overall (OR 0.88, 95 % CI 0.81-0.96) and for ER+ cancer (OR 0.88, 95 % CI 0.80-0.98), but not for ER- cancer (OR 0.93, 95 % CI 0.82-1.06). Overall, there was no strong evidence of effect modification by age, menopausal status, body mass index, and parity. However, our data were suggestive of modification by family history, such that an inverse association was present among women without a family history but not among those with a relative affected by breast cancer. Results from this large pooled analysis provide evidence that vigorous physical activity is associated with a modestly reduced risk of breast cancer in AA women, specifically ER+ cancer.

Obesity and Breast Cancer: A Complex Relationship

As prevalence of obesity continues to rise in the United States, we are beginning to elucidate the complex role of obesity-associated chronic inflammation, endocrine dysfunction, and hormone production as a driver for increased breast cancer risk. Epidemiological data suggest that obesity (BMI > 30) is associated with increased breast cancer incidence, worse prognosis, and higher mortality rates. Mechanistically, obesity and excess fat mass represent a state of chronic inflammation, insulin resistance, adipokine imbalance, and increased estrogen signaling. This pro-tumorigenic environment stimulates cancer development through abnormal growth, proliferation, and survival of mammary tissue. Importantly, obesity is a modifiable risk factor; alterations in cell proliferation, apoptosis, circulating estrogen, and insulin sensitivity are observed in response to weight loss attainable through behavior modification including dietary and exercise changes.

Risk of breast cancer in relation to combined effects of hormone therapy, body mass index, and alcohol use, by hormone-receptor status

BACKGROUND

Alcohol consumption, increased body mass index (BMI), and hormone therapy are risk factors for postmenopausal breast cancer, but their combined effects are not well understood. Because hormone therapy is effective for the relief of menopausal symptoms, the identification of "high-risk" users is important for therapeutic reasons. We investigated interactions between hormone therapy use and alcohol-use/high BMI status in relation to invasive breast cancer risk, both overall and according to estrogen receptor (ER) status.

METHODS

Two Danish prospective cohorts were pooled, including 30,789 women ages 50+ years (study period 1981 to 2009). Information on risk factors was obtained in baseline questionnaires. We performed analyses using the Aalen additive hazards model. Serum estradiol and testosterone measurements were obtained in a subsample of approximately 1000 women.

RESULTS

During 392,938 person-years of follow-up, 1579 women developed invasive breast cancer. Among nonusers of hormone therapy, the risk of breast cancer was slightly increased with overweight/obesity and increasing alcohol consumption. Compared with normal-weight nonusers, the risk of breast cancer was higher in hormone therapy users across all BMI strata (P for interaction = 0.003). A markedly higher risk of breast cancer was also observed for alcohol combined with hormone therapy use compared with abstinent nonusers (P for interaction = 0.02). These effects were primarily restricted to ER-positive cases. Combined effects of hormone therapy/high BMI and hormone therapy/alcohol on serum estradiol and testosterone supported the hypothesis of a hormonal pathway linking these exposures to breast cancer.

CONCLUSION

These analyses suggest an increased risk of breast cancer associated with hormone therapy use-a risk that may be particularly strong among women consuming alcohol.

Exercise and dietary advice intervention for survivors of triple-negative breast cancer: effects on body fat, physical function, quality of life, and adipokine profile

PURPOSE

Regular exercise and healthy eating are routinely recommended for breast cancer survivors, and past studies show benefits in quality of life and decreased inflammation. However, this has not been tested specifically in triple-negative breast cancer survivors. Increasing physical activity and losing body fat are thought to positively affect inflammatory biomarkers that have been associated with breast cancer. Therefore, the primary purpose of this study was to determine if participation in an exercise and dietary counseling program can improve body fat, physical function, and quality of life in survivors of this aggressive breast cancer. Secondarily, we sought to determine if participation in the program had beneficial effects on obesity-related markers of the adipokine profile.

METHODS

Sixty-six survivors of triple-negative breast cancer with BMI >25 were invited to participate. Twenty-eight enrolled and 23 completed the randomized, controlled trial (13 intervention, 10 control). Moderate-intensity aerobic exercise (150 min per week, for 12 weeks) and diet counseling were compared to usual care, education only. The primary outcome of interest was weight loss (body mass, BMI, % fat), and secondary outcomes included physical function (exercise capacity), quality of life (Function After Cancer Therapy-Breast (FACT-B)), cytokines (C-reactive protein (CRP), TNF-α, IL-6), and adipokine profile (leptin, adiponectin, insulin).

RESULTS

Participants in the program lost more body fat (2.4 % loss vs. 0.4 % gain, p < 0.05) than the control group. The intervention group also improved quality of life (FACT-B total score +14 pts) and decreased sedentary time but did not improve peak exercise capacity. The intervention had no effect on serum cytokines and adipokines after 12 weeks in the program. However, serum leptin and adiponectin and their ratio were significantly correlated with BMI in the intervention group (p < 0.05).

CONCLUSIONS

Exercise and dietary counseling led to loss of body fat and improved quality of life in survivors of triple-negative breast cancer. BMI was associated with favorable changes in leptin and adiponectin which may reflect a change in adiposity with intervention. Exercise and healthy eating may be equally effective in this high-risk population as in other breast cancer survivors and should be encouraged as a part of a cancer survivorship program.

The Breast Cancer to Bone (B2B) Metastases Research Program: a multi-disciplinary investigation of bone metastases from breast cancer

Background

Bone is the most common site of breast cancer distant metastasis, affecting 50–70 % of patients who develop metastatic disease. Despite decades of informative research, the effective prevention, prediction and treatment of these lesions remains elusive. The Breast Cancer to Bone (B2B) Metastases Research Program consists of a prospective cohort of incident breast cancer patients and four sub-projects that are investigating priority areas in breast cancer bone metastases. These include the impact of lifestyle factors and inflammation on risk of bone metastases, the gene expression features of the primary tumour, the potential role for metabolomics in early detection of bone metastatic disease and the signalling pathways that drive the metastatic lesions in the bone.

Methods/Design

The B2B Research Program is enrolling a prospective cohort of 600 newly diagnosed, incident, stage I-IIIc breast cancer survivors in Alberta, Canada over a five year period. At baseline, pre-treatment/surgery blood samples are collected and detailed epidemiologic data is collected by in-person interview and self-administered questionnaires. Additional self-administered questionnaires and blood samples are completed at specified follow-up intervals (24, 48 and 72 months). Vital status is obtained prior to each follow-up through record linkages with the Alberta Cancer Registry. Recurrences are identified through medical chart abstractions. Each of the four projects applies specific methods and analyses to assess the impact of serum vitamin D and cytokine concentrations, tumour transcript and protein expression, serum metabolomic profiles and in vitro cell signalling on breast cancer bone metastases.

Discussion

The B2B Research Program will address key issues in breast cancer bone metastases including the association between lifestyle factors (particularly a comprehensive assessment of vitamin D status) inflammation and bone metastases, the significance or primary tumour gene expression in tissue tropism, the potential of metabolomic profiles for risk assessment and early detection and the signalling pathways controlling the metastatic tumour microenvironment. There is substantial synergy between the four projects and it is hoped that this integrated program of research will advance our understanding of key aspects of bone metastases from breast cancer to improve the prevention, prediction, detection, and treatment of these lesions.

Lifestyle in Iranian Patients with Breast Cancer

BACKGROUND

One of the most commonly diagnosed cancers is breast cancer that leads to mortality and morbidity among Iranian women. Behavioural risk factors, such as common lifestyle patterns are often associated with risk of breast cancer incidence.

AIM

This study aimed to investigate lifestyle of breast cancer patients admitted to Cancer Research Center of Mazandaran University of Medical Sciences.

MATERIALS AND METHODS

This descriptive cross-sectional study was conducted using convenient sampling method. Sample size consisted of 150 cancer patients, and data collection tool included a researcher-made questionnaire on dimensions of lifestyle containing four dimensions of self-care, exercise and physical activity, diet and coping with stress. Maximum score in different dimensions, based on 100% of marks earned, was evaluated in three categories of undesirable, relatively desirable and desirable. Data were analysed with SPSS-19 software using descriptive statistics (relative and absolute frequencies, mean and standard deviation).

RESULTS

In total of 150 women, the mean age of patients was 51.9 ± 1.04 (27-78). The majority of participants were married, housewives, with high school education. Among the four parts of healthy lifestyle, desirable level of physical activity and exercise had the least participants, and in the dimensions of physical activity and exercise, the lowest level related to walking, followed by daily exercise. Most of the participants had undesirable level of self-care and lowest frequency related to mammography after 40-year-old, followed by annual check-up and Pap-smear. With regard to nutrition, most of them were at desirable level.

CONCLUSION

The results indicated undesirable levels in two lifestyle dimensions (self-care and physical activity and exercise) in the majority of participants for a year before contracting breast cancer. Primary prevention programs should be implemented with a comprehensive approach, thus, effective strategies are required to modify lifestyle.

Reduced risk of breast cancer associated with recreational physical activity varies by HER2 status

Convincing epidemiologic evidence indicates that physical activity is inversely associated with breast cancer risk. Whether this association varies by the tumor protein expression status of the estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2), or p53 is unclear. We evaluated the effects of recreational physical activity on risk of invasive breast cancer classified by the four biomarkers, fitting multivariable unconditional logistic regression models to data from 1195 case and 2012 control participants in the population-based Women’s Contraceptive and Reproductive Experiences Study. Self-reported recreational physical activity at different life periods was measured as average annual metabolic equivalents of energy expenditure [MET]-hours per week. Our biomarker-specific analyses showed that lifetime recreational physical activity was negatively associated with the risks of ER-positive (ER+) and of HER2-negative (HER2−) subtypes (both P_trend ≤ 0.04), but not with other subtypes (all P_trend > 0.10). Analyses using combinations of biomarkers indicated that risk of invasive breast cancer varied only by HER2 status. Risk of HER2–breast cancer decreased with increasing number of MET-hours of recreational physical activity in each specific life period examined, although some trend tests were only marginally statistically significant (all P_trend ≤ 0.06). The test for homogeneity of trends (HER2– vs. HER2+ ) reached statistical significance only when evaluating physical activity during the first 10 years after menarche (P_homogeneity = 0.03). Our data suggest that physical activity reduces risk of invasive breast cancers that lack HER2 overexpression, increasing our understanding of the biological mechanisms by which physical activity acts.

Associations of objectively assessed physical activity and sedentary time with all-cause mortality in US adults: the NHANES study

Background

Sedentary behavior is related to increased mortality risk. Whether such elevated risk can be offset by enhanced physical activity has not been examined using accelerometry data.

Materials and Methods

We examined the relations of sedentary time and physical activity to mortality from any cause using accelerometry data among 1,677 women and men aged 50 years or older from the National Health and Nutrition Examination Survey (NHANES) 2003–2004 cycle with follow-up through December 31, 2006.

Results

During an average follow-up of 34.67 months and 4,845.42 person-years, 112 deaths occurred. In multivariate Cox proportional hazard models, greater sedentary time (≥ median of 8.60 hours/day) was associated with increased risk of mortality from any cause (relative risk (RR) = 2.03; 95% confidence interval (CI) = 1.09-3.81). Low level of moderate to vigorous physical activity (< median of 6.60 minutes/day) was also related to enhanced all-cause mortality risk (RR = 3.30; 95% CI = 1.33-8.17). In combined analyses, greater time spent sedentary and low levels of moderate to vigorous physical activity predicted a substantially elevated all-cause mortality risk. As compared with the combination of a low sedentary level and a high level of moderate to vigorous physical activity, the risks of mortality from all causes were 4.38 (95% CI = 1.26-15.16) for low levels of both sedentary time and physical activity, 2.79 (95% CI = 0.77-10.12) for greater time spent sedentary and high physical activity level, and 7.79 (95% CI = 2.26-26.82) for greater time spent sedentary and low physical activity level. The interaction term between sedentary time and moderate to vigorous physical activity was not statistically significant (p = 0.508).

Conclusions

Both high levels of sedentary time and low levels of moderate to vigorous physical activity are strong and independent predictors of early death from any cause. Whether a high physical activity level removes the increased risk of all-cause mortality related to sedentariness requires further investigation.

Yoga and meditation for menopausal symptoms in breast cancer survivors-A randomized controlled trial

BACKGROUND

Breast cancer survivors have only very limited treatment options for menopausal symptoms. The objective of this trial was to evaluate the effects of a 12-week traditional Hatha yoga and meditation intervention on menopausal symptoms in breast cancer survivors.

METHODS

Patients were randomly assigned either to a 12-week yoga and meditation intervention or to usual care. The primary outcome measure was total menopausal symptoms (Menopause Rating Scale [MRS] total score). Secondary outcome measures included MRS subscales, quality of life (Functional Assessment of Cancer Therapy-Breast), fatigue (Functional Assessment of Chronic Illness Therapy-Fatigue), depression, and anxiety (Hospital Anxiety and Depression Scale). Outcomes were assessed at week 12 and week 24 after randomization.

RESULTS

In total, 40 women (mean age ± standard deviation, 49.2 ± 5.9 years) were randomized to yoga (n = 19) or to usual care (n = 21). Women in the yoga group reported significantly lower total menopausal symptoms compared with the usual care group at week 12 (mean difference, -5.6; 95% confidence interval, -9.2 to -1.9; P = .004) and at week 24 (mean difference, -4.5; 95% confidence interval, -8.3 to -0.7; P = .023). At week 12, the yoga group reported less somatovegetative, psychological, and urogenital menopausal symptoms; less fatigue; and improved quality of life (all P < .05). At week 24, all effects persisted except for psychological menopausal symptoms. Short-term effects on menopausal symptoms remained significant when only women who were receiving antiestrogen medication (n = 36) were analyzed. Six minor adverse events occurred in each group.

CONCLUSIONS

Yoga combined with meditation can be considered a safe and effective complementary intervention for menopausal symptoms in breast cancer survivors. The effects seem to persist for at least 3 months.

Cancer risk in people with diabetes: Does physical activity and adiposity modify the association? Prospective data from the HUNT Study, Norway

AIMS

To examine whether physical activity and adiposity modify the increased risk of cancer associated with diabetes.

METHODS

We prospectively examined the association of diabetes and risk of cancer among 73,726 persons stratified by physical activity and body mass index (BMI). Adjusted hazard ratios (HRs) with 95% confidence intervals (CI) were estimated from Cox regression.

RESULTS

During a median follow-up of 22.0 years, 9572 people were diagnosed with incident cancer. There was no clear association between diabetes and cancer risk in those reporting high levels of physical activity (≥2.0h per week) (HR 0.93; 95% CI: 0.70-1.24) or those with a normal weight (BMI <25kg/m²) (HR 1.02; 95% CI: 0.84-1.25). However, among people with diabetes who reported low levels of physical activity (<2.0h per week), diabetes was associated with an HR of 1.15 (95% CI: 1.01-1.31). Correspondingly, diabetes was associated with an HR of 1.21 (95% CI: 1.07-1.37) among overweight or obese people (BMI ≥25kg/m²).

CONCLUSIONS

There was evidence that the increased risk of cancer associated with diabetes was confined to persons who reported low levels of physical activity, or who were overweight or obese.

The role of physical exercise in the development of breast cancer

Breast cancer is one of the most common types of cancer among women worldwide. Epidemiological and experimental studies confirm the beneficial effects of physical exercise both in patients who have suffered a relapse and in those who are in the course of a treatment. Researchers suggest that regular physical effort performed 3-5 times a week at 20-40 MET reduces the risk of development of breast cancer. Scientific evidence suggests that aerobic training can be safe and effective even during the oncological treatment, which, depending on the stage of the disease, may consist of surgical treatment combined with chemotherapy, radiotherapy or hormone therapy. In addition, it significantly improves the function of the circulatory and respiratory systems, reduces fatigue and improves the quality of life of patients struggling with the disease. There are many theories on the mechanisms that are triggered by aerobic workout. Despite the numerous studies on this subject, which have been conducted over the years, we still cannot say how physical activity reduces the risk of development of breast cancer. The most frequently mentioned biological mechanisms include the influence of oestrogen, metabolic hormones, growth factor, inflammatory markers, response from the immune system, insulin resistance and oxidative stress. Many studies into the process of carcinogenesis are carried out in laboratory conditions on animals. Due to application of different experimental models, the results of such studies are often ambiguous. Nevertheless, scientists see a huge potential in this kind of experiments, because some of them have already attested to the protective effects of physical exercise against the appearance of breast cancer, but also they have increased our understanding of the processes through which this risk is reduced. Perhaps, in the future physical activity will become a part of a cancer treatment thanks to the results of such studies.

Oxidative stress and skin diseases: possible role of physical activity

BACKGROUND

The skin is the largest body organ that regulates excretion of metabolic waste products, temperature, and plays an important role in body protection against environmental physical and chemical, as well as biological factors. These include agents that may act as oxidants or catalysts of reactions producing reactive oxygen species (ROS), reactive nitrogen species (RNS), and other oxidants in skin cells. An increased amount of the oxidants, exceeding the antioxidant defense system capacity is called oxidative stress, leading to chronic inflammation, which, in turn, can cause collagen fragmentation and disorganization of collagen fibers and skin cell functions, and thus contribute to skin diseases including cancer. Moreover, research suggests that oxidative stress participates in all stages of carcinogenesis. We report here a summary of the present state of knowledge on the role of oxidative stress in pathogenesis of dermatologic diseases, defensive systems against ROS/RNS, and discuss how physical activity may modulate skin diseases through effects on oxidative stress. The data show duality of physical activity actions: regular moderate activity protects against ROS/RNS damage, and endurance exercise with a lack of training mediates oxidative stress. These findings indicate that the redox balance should be considered in the development of new antioxidant strategies linked to the prevention and therapy of skin diseases.

The role of diet, weight control and physical activity in breast cancer survivors

SUMMARY 

Recent advances in breast cancer (BC) treatment and improved screening have resulted in an increasing number of BC survivors. However, since recurrences are still a relatively common event there is a critical need to investigate modifiable factors that could impact disease recurrence and long-term prognosis. There is substantial evidence from observational studies and increasingly from randomized controlled trials, showing that weight management, increased physical activity and dietary modification may be effective methods to improve BC survival and reduce recurrences, due to their interrelated beneficial effects on systemic inflammation, circulating reproductive hormones and metabolic imbalances. Although ongoing randomized controlled trials should be able to confirm the role of these lifestyle factors on BC prognosis, further research is needed to establish specific lifestyle recommendations.

A prospective study of physical activity and breast cancer incidence in African-American women

BACKGROUND

Physical activity has been associated with reduced risk of breast cancer. Evidence on the association in African Americans is limited.

METHODS

With prospective data from the Black Women's Health Study, we assessed vigorous exercise and walking in relation to incidence of invasive breast cancer overall (n = 1,364), estrogen receptor-positive (ER(+), n = 688) cancer, and estrogen receptor-negative (ER(-), n = 405) cancer, based on 307,672 person-years of follow-up of 44,708 African-American women ages 30 years or older at enrollment. Cox proportional hazards models estimated incidence rate ratios (IRR) and 95% confidence intervals (CI).

RESULTS

Vigorous exercise at baseline was inversely associated with overall breast cancer incidence (Ptrend = 0.05): the IRR for ≥7 h/wk relative to <1 h/wk was 0.74 (95% CI, 0.57-0.96). The association did not differ by ER status. Brisk walking for ≥7 h/wk was associated with a reduction similar to that for vigorous exercise. Vigorous exercise at the age of 30 years, 21 years, or in high school was not associated with breast cancer incidence. Sitting for long periods at work or watching TV was not significantly associated with breast cancer incidence.

CONCLUSION

High levels of vigorous exercise or brisk walking may be associated with a reduction in incidence of breast cancer in African-American women.

IMPACT

These results provide informative data on a potential modifiable risk factor, exercise, for breast cancer in African-American women.

Effect of exercise on insulin sensitivity in healthy postmenopausal women: the SHAPE study

BACKGROUND

An inactive lifestyle is a risk factor for several types of cancer. A proposed pathway through which exercise influences cancer risk is via insulin. We aim to investigate the effect of a one-year exercise intervention on insulin sensitivity, and the role of body fat in this association, in healthy, normal to overweight/obese, postmenopausal women.

METHODS

In the Sex Hormones And Physical Exercise (SHAPE) study, 189 healthy, inactive and postmenopausal women [ages, 50-69 years; body mass index (BMI), 22-40 kg/m(2)] were randomly assigned to a one-year aerobic and strength exercise intervention (150 min/wk), or a control group. Between-group differences in fasting insulin, glucose, and homeostatic model assessment of insulin resistance (HOMA2) over time were estimated using linear mixed models.

RESULTS

Follow-up measurements of insulin sensitivity were available for 181 (95.8%) and 182 (96.3%) women at 4 and 12 months, respectively. The intention-to-treat analysis showed no significant differences between the two study groups [treatment effect ratio of the exercise group vs. control (β; 95% confidence interval): insulin, β, 1.07 (0.96-1.19); glucose, β, 1.01 (0.99-1.02); and HOMA2, β, 1.07 (0.96-1.20)]. Similar results were found in a per protocol analysis in compliant women, and in a subgroup of women who lost >2% body fat [measured by dual-energy X-ray absorptiometry (DEXA)].

CONCLUSIONS

Participation in a one-year aerobic and strength exercise intervention program did not result in changes in insulin sensitivity in healthy postmenopausal and inactive women.

IMPACT

Our findings suggest that 150 min/wk of exercise, as recommended by current guidelines, is not enough to achieve improvements in insulin sensitivity and subsequent cancer risk, in healthy postmenopausal women.

Differential impact of body mass index on absolute and percent breast density: implications regarding their use as breast cancer risk biomarkers

Percent breast density (PBD), a commonly used biomarker of breast cancer risk (BCR), is confounded by the influence of non-dense breast tissue on its measurement and factors, such as BMI, which have an impact on non-dense tissue. Consequently, BMI, a potent BCR factor, is, paradoxically, negatively correlated with PBD. We propose that absolute breast density (ABD) is a more accurate biomarker of BCR. We used a volumetric method to compare the correlation between PBD and ABD with baseline demographics and dietary and physical activity variables in a group of 169 postmenopausal women enrolled in a clinical trial prior to any intervention. As expected, a strong negative correlation between PBD and BMI was observed (Rho = -0.5, p < 5e(-12)). In contrast, we observed a strong, previously not well established, positive correlation of BMI with ABD (Rho = 0.41, p < 2.5e(-8)), which supports the use of ABD as a more accurate indicator of BCR. Correction of PBD by BMI did not frequently provide the same information as ABD. In addition, because of the strong influence of BMI on ABD, many correlations between dietary variables and ABD did not emerge, until adjustment was made for BMI. ABD corrected by BMI should be the gold standard BD measurement. These findings identify the optimal measurement of BD when testing the influence of an intervention on BD as a biomarker of BCR.

Nutrition and physical activity influence on breast cancer incidence and outcome

INTRODUCTION AND AIMS

To provide a current perspective on nutrition and physical activity influence on breast cancer.

METHODS AND RESULTS

A comprehensive literature review was conducted and selective presentation of findings follows. While some observational studies have associated higher dietary fat intake with higher breast cancer incidence, two full-scale randomized, clinical trials of dietary fat intake reduction programs were negative. However, a lifestyle intervention targeting fat intake reduction in the Women's Intervention Nutrition Study (WINS), resulted in weight loss and also reduced breast cancer recurrences in women with early stage disease. Observational studies evaluating specific nutrient intakes and dietary supplements have provided mixed results. Several observational studies find women with early stage breast cancer with lower 25-hydroxyvitamin D levels at higher recurrence risk, a finding requiring cautious interpretation. The lifestyle factor most strongly and consistently associated with both breast cancer incidence and breast cancer recurrence risk is physical activity. A meta-analyses of observational studies supports the concept that moderate recreational physical activity (about 3-4 h walking per week) may reduce breast cancer incidence and that women with early stage breast cancer who increased or maintain their physical activity may have lower recurrence risk as well. Feasibility of achieving increased physical activity and weight loss in women with early-stage breast cancer has been established. Two full-scale randomized clinical trials are evaluating weight loss/maintenance and increased physical activity in relation to recurrence risk in women with early-stage, resected breast cancer.

DISCUSSION/CONCLUSIONS

Dietary intake may influence breast cancer but influence is difficult to separate from influence of body weight. A consistent body of observational study evidence suggests higher physical activity has favorable influence on breast cancer incidence and outcome. While awaiting definitive evidence from ongoing randomized trials, breast cancer patients can reasonably be counseled to avoid weight gain and reduce body weight if overweight or obese and increase or maintain a moderate level of physical activity.

Breast cancer risk accumulation starts early: prevention must also

Nearly one in four breast cancers is diagnosed before the age of 50, and many early-stage premalignant lesions are present but not yet diagnosed. Therefore, we review evidence to support the strategy that breast cancer prevention efforts must begin early in life. This study follows the literature review methods and format. Exposures during childhood and adolescence affect a woman's long-term risk of breast cancer, but have received far less research attention than exposures that occur later in life. Breast tissue undergoes rapid cellular proliferation between menarche and first full-term pregnancy, and risk accumulates rapidly until the terminal differentiation that accompanies first pregnancy. Evidence on childhood diet and growth in height, and adolescent alcohol intake, among other adolescent factors is related to breast cancer risk and risk of premalignant proliferative benign lesions. Breast cancer prevention efforts will have the greatest effect when initiated at an early age and continued over a lifetime. Gaps in knowledge are identified and deserve increase attention to inform prevention.

Randomized controlled trial to evaluate the effects of combined progressive exercise on metabolic syndrome in breast cancer survivors: rationale, design, and methods

Background

Metabolic syndrome (MetS) is increasingly present in breast cancer survivors, possibly worsened by cancer-related treatments, such as chemotherapy. MetS greatly increases risk of cardiovascular disease and diabetes, co-morbidities that could impair the survivorship experience, and possibly lead to cancer recurrence. Exercise has been shown to positively influence quality of life (QOL), physical function, muscular strength and endurance, reduce fatigue, and improve emotional well-being; however, the impact on MetS components (visceral adiposity, hyperglycemia, low serum high-density lipoprotein cholesterol, hypertriglyceridemia, and hypertension) remains largely unknown. In this trial, we aim to assess the effects of combined (aerobic and resistance) exercise on components of MetS, as well as on physical fitness and QOL, in breast cancer survivors soon after completing cancer-related treatments.

Methods/Design

This study is a prospective randomized controlled trial (RCT) investigating the effects of a 16-week supervised progressive aerobic and resistance exercise training intervention on MetS in 100 breast cancer survivors. Main inclusion criteria are histologically-confirmed breast cancer stage I-III, completion of chemotherapy and/or radiation within 6 months prior to initiation of the study, sedentary, and free from musculoskeletal disorders. The primary endpoint is MetS; secondary endpoints include: muscle strength, shoulder function, cardiorespiratory fitness, body composition, bone mineral density, and QOL. Participants randomized to the Exercise group participate in 3 supervised weekly exercise sessions for 16 weeks. Participants randomized to the Control group are offered the same intervention after the 16-week period of observation.

Discussion

This is the one of few RCTs examining the effects of exercise on MetS in breast cancer survivors. Results will contribute a better understanding of metabolic disease-related effects of resistance and aerobic exercise training and inform intervention programs that will optimally improve physiological and psychosocial health during cancer survivorship, and that are ultimately aimed at improving prognosis.

Trial registration

NCT01140282; Registration: June 10, 2010

Adolescent physical activity in relation to breast cancer risk

Adolescent physical activity may protect against premenopausal breast cancer. Whether it also prevents postmenopausal breast cancer, and whether associations are independent of adult activity, is unclear. We evaluated this association among 75,669 women in the Nurses' Health Study II. In 1997, participants reported strenuous, moderate, and walking activity (hours/week) at ages 12-13, 14-17, 18-22, and 23-29 years. We estimated metabolic equivalent task hours (MET-h)/week. Participants also reported current physical activity over follow-up. Breast cancer diagnoses (n = 2,697; premenopausal = 1,351; postmenopausal = 965) through 2011 were reported by participants and confirmed with medical records. We additionally stratified analyses by median age at diagnosis. In Cox proportional hazards models adjusted for adolescent characteristics, physical activity from ages 14-22 was modestly inversely associated with premenopausal breast cancer [e.g., hazard ratio (HR) comparing 72+ to <21 MET-h/week 0.81 (95 % confidence interval (CI) 0.69-0.95; p-trend = 0.10) for ages 14-17 and 0.85 (95 % CI 0.71-1.02; p-trend = 0.06 for ages 18-22]. However, adjustment for adult activity and additional breast cancer risk factors attenuated the associations [ages 14-17: 0.85 (95 % CI 0.73-1.00; p-trend = 0.33)]. Associations were stronger among women diagnosed at younger ages [e.g., ages 18-22, HR 0.77 (95 % CI 0.60-0.99; p-trend = 0.05) for women diagnosed before 46.9 years; HR 1.02 (95 % CI 0.79-1.32; p-trend = 0.94) for those diagnosed at/after 46.9 years]. Early life physical activity was not associated with postmenopausal breast cancer. Overall, adolescent physical activity was not associated with breast cancer risk. However, we observed a suggestive inverse association of physical activity at ages 14-22 years with premenopausal breast cancer.

Physical activity and its relation to cancer risk: updating the evidence

Scientific evidence for the primary prevention of cancer caused by physical activity of regular moderate-intensity or greater is rapidly accumulating in this field. About 300 epidemiologic studies on the association between physical activity and cancer risk have been conducted worldwide. The objectives of this paper were three-fold: (i) to describe briefly the components of physical activity and its quantification; (ii) to summarize the most important conclusions available from comprehensive reports, and reviews of the epidemiologic individual and intervention studies on a role physical activity in cancer prevention; (iii) to present proposed biological mechanisms accounting for effects of activity on cancer risk. The evidence of causal linked physical activity and cancer risk is found to be strong for colon cancer - convincing; weaker for postmenopausal breast and endometrium cancers - probable; and limited suggestive for premenopausal breast, lung, prostate, ovary, gastric and pancreatic cancers. The average risk reductions were reported to be 20-30%. The protective effects of physical activity on cancer risk are hypothesized to be through multiple interrelated pathways: decrease in adiposity, decrease in sexual and metabolic hormones, changes in biomarkers and insulin resistance, improvement of immune function, and reduction of inflammation. As there are several gaps in the literature for associations between activity and cancer risk, additional studies are needed. Future research should include studies dealing with limitations in precise estimates of physical activity and of a lack of consensus on what defines sedentary behavior of individuals and those linked with the proposed biomarkers to cancer risk and controlled exercise intervention trials.

Physical activity and the risk of postmenopausal breast cancer - the Norwegian Women and Cancer Study

Background

The relationship between physical activity (PA) throughout life and the risk of postmenopausal breast cancer overall and by estrogen receptor (ER) and progesterone receptor (PR) status, has been reported, but without consistent results. The present study aimed to investigate PA from young age to adulthood in participants of the Norwegian Women and Cancer (NOWAC) Study, in order to determine whether changes in PA level affect the risk of postmenopausal breast cancer.

Methods

1767 invasive breast cancer cases were identified among 80,202 postmenopausal participants of the NOWAC Study during 8.2 years of median follow-up. PA levels at age 14 years, 30 years and at cohort enrollment were obtained via a self-administered questionnaire. Multivariate Cox proportional hazard regression models were used to estimate relative risks and 95% confidence intervals of the risk of postmenopausal breast cancer overall and by ER/PR status.

Results

Risk of postmenopausal breast cancer overall and by ER/PR status was not associated with physical activity level at enrollment. Women with a low PA level at age 30 had an increased risk of ER+/PR + breast tumors (P for trend = 0.04) compared to women with a moderate physical activity level at age 30. Women with a low physical activity level at all three periods of life had a 20% significantly reduced risk of postmenopausal breast cancer, as well as a reduced risk of ER+/PR + and ER+/PR- breast tumors, compared with women who maintained a moderate physical activity level. However, when analyses were corrected for multiple tests, the result was no longer statistically significant. The findings were consistent over strata of age, body mass index and use of hormone replacement therapy.

Conclusions

The study results from this large Norwegian cohort do not support an association between physical activity at different periods of life and the risk of postmenopausal breast cancer.

Association of obesity and circulating adipose stromal cells among breast cancer survivors

A positive association of obesity with breast cancer incidence and mortality is well established. Recent reports indicate that adipose stromal cells (ASCs) play an important role in breast cancer development and progression by producing estrogens and tumor-promoting cytokines. Furthermore, circulating ASCs have been uniquely detected in obese individuals, which is likely due to increased tissue remodeling and cell mobilization. The number of circulating ASCs is even more prominent in obese patients with colon and prostate cancers, both of which are exacerbated by obesity. To determine whether a similar association exists for breast cancer, we collected blood samples from a cohort of breast cancer survivors and enumerated circulating ASCs by flow cytometry on the basis of the previously established ASC-associated immunophenotype (CD34+/CD31-/CD45-). We found significantly higher levels of circulating ASCs (p<0.001) in breast cancer survivors with body mass index (BMI)≥30 kg/m2 than their non-obese counterparts (BMI<30). We also compared circulating ASCs before and after exercise of only the obese subjects enrolled in a 6-month individualized exercise program, but found no statistically significant difference, likely due to limited number of subjects in the study. Our findings suggest that circulating ASCs can serve as a potential biomarker for future studies of the impacts of obesity and physical activity on breast cancer recurrence and survival.

The Influence of Energetic Factors on Biomarkers of Postmenopausal Breast Cancer Risk

Strong and consistent evidence exists that physical activity reduces breast cancer risk by 10-25 %, and several proposed biologic mechanisms have now been investigated in randomized, controlled, exercise intervention trials. Leading hypothesized mechanisms relating to postmenopausal breast cancer include adiposity, endogenous sex hormones, insulin resistance, and chronic low-grade inflammation. In addition, other pathways are emerging as potentially important, including those involving oxidative stress and telomere length, global DNA hypomethylation, immune function, and vitamin D exposure. Recent exercise trials in overweight/obese postmenopausal women implicate weight loss as a mechanism whereby exercise induces favorable changes in circulating estradiol levels and other biomarkers as well. Still it is plausible that some exercise-induced biomarker changes do not require loss of body fat, whereas others depend on abdominal fat loss. We highlight the latest findings from randomized, controlled trials of healthy postmenopausal women, relating exercise to proposed biomarkers for postmenopausal breast cancer risk.

Association of sedentary behaviour with colon and rectal cancer: a meta-analysis of observational studies

BACKGROUND

Sedentary behaviour is ubiquitous in modern society. Emerging studies have focused on the health consequences of sedentary behaviour, including colorectal cancer, but whether sedentary behaviour is associated with the risks of colon and rectal cancer remains unclear. No systematic reviews have applied quantitative techniques to independently compute summary risk estimates. We aimed to conduct a meta-analysis to investigate this issue.

METHODS

We searched PubMed, Embase, and Google Scholar databases up to May 2013 to identify cohort and case-control studies that evaluated the association between sedentary behaviour and colon or rectal cancer. A random-effect model was used to pool the results of included studies. Publication bias was assessed by using Begg's funnel plot.

RESULTS

Twenty-three studies with 63 reports were included in our meta-analysis. These groups included 4,324,462 participants (27,231 colon cancer cases and 13,813 rectal cancer cases). Sedentary behaviour was significantly associated with colon cancer (relative risk (RR): 1.30, 95% confidence interval (CI): 1.22-1.39) but did not have a statistically significant association with rectal cancer (RR 1.05, 95% CI, 0.98-1.13). Subgroup analyses suggested that the odds ratio (OR) of colon cancer was 1.46 (95% CI: 1.22-1.68) in the case-control studies, and the RR was 1.27 (95% CI: 1.18-1.36) in the cohort studies, the OR of rectal cancer was 1.06 (95% CI: 0.85-1.33) in the case-control studies, and the RR was 1.06 (95% CI, 1.01-1.12) in the cohort studies.

CONCLUSION

Sedentary behaviour is associated with an increased risk of colon cancer. Subgroup analyses suggest a positive association between sedentary behaviour and risk of rectal cancer in cohort studies. Reducing sedentary behaviour is potentially important for the prevention of colorectal cancer.

Cancer, physical activity, and exercise

This review examines the relationship between physical activity and cancer along the cancer continuum, and serves as a synthesis of systematic and meta-analytic reviews conducted to date. There exists a large body of epidemiologic evidence that conclude those who participate in higher levels of physical activity have a reduced likelihood of developing a variety of cancers compared to those who engage in lower levels of physical activity. Despite this observational evidence, the causal pathway underlying the association between participation in physical activity and cancer risk reduction remains unclear. Physical activity is also a useful adjunct to improve the deleterious sequelae experienced during cancer treatment. These deleterious sequelae may include fatigue, muscular weakness, deteriorated functional capacity, and many others. The benefits of physical activity during cancer treatment are similar to those experienced after treatment. Despite the growing volume of literature examining physical activity and cancer across the cancer continuum, a number of research gaps exist. There is little evidence on the safety of physical activity among all cancer survivors, as most trials have selectively recruited participants. The specific dose of exercise needed to optimize primary cancer prevention or symptom control during and after cancer treatment remains to be elucidated.

Lack of exercise is a major cause of chronic diseases

Chronic diseases are major killers in the modern era. Physical inactivity is a primary cause of most chronic diseases. The initial third of the article considers: activity and prevention definitions; historical evidence showing physical inactivity is detrimental to health and normal organ functional capacities; cause versus treatment; physical activity and inactivity mechanisms differ; gene-environment interaction (including aerobic training adaptations, personalized medicine, and co-twin physical activity); and specificity of adaptations to type of training. Next, physical activity/exercise is examined as primary prevention against 35 chronic conditions [accelerated biological aging/premature death, low cardiorespiratory fitness (VO2max), sarcopenia, metabolic syndrome, obesity, insulin resistance, prediabetes, type 2 diabetes, nonalcoholic fatty liver disease, coronary heart disease, peripheral artery disease, hypertension, stroke, congestive heart failure, endothelial dysfunction, arterial dyslipidemia, hemostasis, deep vein thrombosis, cognitive dysfunction, depression and anxiety, osteoporosis, osteoarthritis, balance, bone fracture/falls, rheumatoid arthritis, colon cancer, breast cancer, endometrial cancer, gestational diabetes, pre-eclampsia, polycystic ovary syndrome, erectile dysfunction, pain, diverticulitis, constipation, and gallbladder diseases]. The article ends with consideration of deterioration of risk factors in longer-term sedentary groups; clinical consequences of inactive childhood/adolescence; and public policy. In summary, the body rapidly maladapts to insufficient physical activity, and if continued, results in substantial decreases in both total and quality years of life. Taken together, conclusive evidence exists that physical inactivity is one important cause of most chronic diseases. In addition, physical activity primarily prevents, or delays, chronic diseases, implying that chronic disease need not be an inevitable outcome during life.

Exercise in the prevention and rehabilitation of breast cancer

Breast cancer is the most common type of cancer among women worldwide. Several epidemiological studies have shown an inverse relationship between the risk of breast cancer and physical activity levels, whereas exercise training has been recognized as a significant means in the rehabilitation process of breast cancer survivors. The relative risk reduction of breast cancer for women who engaged in moderate to vigorous physical activity for 3-5 days peek week ranged between 20-40 %. Furthermore, several studies demonstrated a 24-67 % reduction in the risk of total deaths and 50-53 % reduction in the risk of breast cancer deaths in women who are physically active after breast cancer diagnosis compared with sedentary women. Breast cancer survivors should be encouraged to participate in rehabilitation programs in order to obtain numerous physiological and psychological benefits. These include reductions in fatigue and improvements in immune function, physical functioning, body composition, and quality of life. Based on recent scientific evidence, a complete rehabilitation program for patients with breast cancer should combine both strength and aerobic exercise in order to maximize the expected benefits.

A prospective investigation of predictive and modifiable risk factors for breast cancer in unaffected BRCA1 and BRCA2 gene carriers

Background

Breast cancer is the most common female cancer worldwide. The lifetime risk of a woman being diagnosed with breast cancer is approximately 12.5%. For women who carry the deleterious mutation in either of the BRCA genes, BRCA1 or BRCA2, the risk of developing breast or ovarian cancer is significantly increased. In recent years there has been increased penetrance of BRCA1 and BRCA2 associated breast cancer, prompting investigation into the role of modifiable risk factors in this group. Previous investigations into this topic have relied on participants recalling lifetime weight changes and subjective methods of recording physical activity. The influence of obesity-related biomarkers, which may explain the link between obesity, physical activity and breast cancer risk, has not been investigated prospectively in this group. This paper describes the design of a prospective cohort study investigating the role of predictive and modifiable risk factors for breast cancer in unaffected BRCA1 and BRCA2 gene mutation carriers.

Methods/design

Participants will be recruited from breast cancer family risk clinics and genetics clinics. Lifestyle risk factors that will be investigated will include body composition, metabolic syndrome and its components, physical activity and dietary intake. PBMC telomere length will be measured as a potential predictor of breast cancer occurrence. Measurements will be completed on entry to the study and repeated at two years and five years. Participants will also be followed annually by questionnaire to track changes in risk factor status and to record cancer occurrence. Data will be analysed using multiple regression models. The study has an accrual target of 352 participants.

Discussion

The results from this study will provide valuable information regarding the role of modifiable lifestyle risk factors for breast cancer in women with a deleterious mutation in the BRCA gene. Additionally, the study will attempt to identify potential blood biomarkers which may be predictive of breast cancer occurrence.

The effect of aerobic exercise on metabolic and inflammatory markers in breast cancer survivors--a pilot study

PURPOSE

Physical activity is associated with a reduced risk of breast cancer development and recurrence. There are several hypothesised mechanisms for this including positive effects on metabolic and inflammatory biomarkers and favourable changes in anthropometric variables. This pilot study examined the effect of an 8-week aerobic exercise intervention on several of these outcomes, including body composition, the metabolic syndrome, C-reactive protein (CRP) and physical activity, in breast cancer survivors 2-6 months post-chemotherapy.

METHODS

Assessments were completed at baseline, at 8-weeks and 3-months post-intervention. Measures taken following a 12-h fast included body composition (bioimpedance analysis), metabolic syndrome (waist circumference, blood pressure, high-density lipoprotein cholesterol, triglycerides and fasting glucose), insulin resistance (homeostatic model assessment), CRP and physical activity (accelerometry and questionnaire). Participants were randomized to either an 8-week moderate-intensity aerobic exercise group or a usual-care control group. Analysis was completed using repeated-measures analysis of variance (ANOVA) (p = 0.05).

RESULTS

Twenty-six breast cancer survivors participated (mean (standard deviation) age 48.1 (8.8) years, exercise group; n = 16, control group; n = 10). At baseline, 13 participants were overweight, 6 were obese and 19 centrally obese. Intention-to-treat analysis revealed no significant differences between the exercise and control groups in any of the outcomes measures; however, analysis of those who adhered to >90 % of the supervised exercise class showed a significant decrease in waist circumference (p = 0.05) and a significant increase in subjectively reported "total weekly" (p = 0.005) activity.

CONCLUSION

While this 8-week aerobic exercise pilot intervention did not elicit significant improvements in biomarkers of breast cancer risk, there was some suggestion of improvements in waist circumference and subjectively measured physical activity in participants with >90 % adherence to the programme. A trial of longer duration and greater subject numbers is warranted.

Intensity of recreational physical activity in different life periods in relation to breast cancer among women in the region of Western Pomerania

Background

Recreational physical activity has been consistently associated with lower breast cancer risk, but there is a need to study the intensity and duration of activity that are critical to reduce the risk. The aim of this study was to examine the influence of moderate and vigorous intensity of recreational physical activity performed at different age periods on breast cancer risk.

Material and methods

The case-control study included 858 women with histological confirmation of invasive breast cancer and 1085 women free of any cancer diagnosis, residents of the region of Western Pomerania, aged 28–79 years. The frequency, duration and intensity of lifetime household, occupational and recreational physical activity, sociodemographic characteristics, reproductive factors, family history of breast cancer, current weight and height, and lifestyle habits were measured using a self-administered questionnaire. Unconditional logistic regression analyses were applied to estimate odds ratios (ORs) and 95% confidence intervals (CIs). The risk estimates were controlled for potential risk factors and lifetime household and occupational activities.

Results

We found a risk reduction for recreational activity done early in life (age periods 14–20, 21–34, 35–50 years), particularly at ages 14–20 and 21–34 years, regardless of intensity. Active women engaging in more than 4.5 hours per week of moderate activity during ages 14–20 years had, on average, a 36% lower risk (OR = 0.64, 95% CI: 0.45–0.89) than women who were never or rarely active. For the women who reported 4.5 hours per week of vigorous activity during this period we found about 64% risk reduction (OR = 0.36, 95% CI: 0.26–0.51). For the period after 50 years of age, recreational activity of moderate or vigorous intensity was not significantly associated with the risk.

Conclusions

Recreational physical activity of moderate or vigorous intensity done during adolescence, early and middle adulthood, particularly at ages 14–20 and 21–34 years, is associated with significantly decreased breast cancer risk.