Physical activity and breast cancer risk: impact of timing, type and dose of activity and population subgroup effects

Lifestyle Factors and Cancer: A Narrative Review

Lifestyle factors and their impact on cancer prevention, prognosis, and survivorship are increasingly recognized in the medical literature. Lifestyle factors are primarily defined here as diet and physical activity. We conducted a narrative review of the primary published data, including randomized controlled trials and prospective studies, on the impact of primary lifestyle factors on oncogenesis and clinical outcomes in the preventative and survivorship setting. First, we discuss the oncogenic mechanisms behind primary lifestyle factors (diet, physical activity and, within these 2, obesity). Then, we discuss the impact of adherence to lifestyle guidelines and dietary patterns on cancer incidence based on primary data. Owing to the plethora of published literature, to summarize the data in a more efficient manner, we describe the role of physical activity on cancer incidence using summative systematic reviews. We end by synthesizing the primary data on lifestyle factors in the survivorship setting and conclude with potential future directions. In brief, the various large-scale studies investigating the role diet and physical activity have reported a beneficial effect on cancer prevention and survivorship. Although the impact of single lifestyle factors on cancer incidence risk reduction is generally supported, holistic approaches to address the potential synergistic impact of multiple lifestyle factors together in concert is limited. Future research to identify the potentially synergistic effects of lifestyle modifications on oncogenesis and clinical outcomes is needed, particularly in cancer subtypes beyond colorectal and breast cancers.

Physical Activity and Mammographic Density in Japanese Women

BACKGROUND

Dense breast is one of the strong risk factors for breast cancer among women. While it has been established that physical activity is associated with decreased risk for breast cancer, results have been inconsistent in terms of mammographic density. Thus, we examined physical activity in relation to mammographic density among Japanese women in Tokyo.

METHODS

We used 123,026 records from 33,698 Japanese women without a history of breast cancer who got mammograms at St. Luke's International Hospital in Tokyo, Japan from 2004 to 2019. Mammographic density was classified according to the Breast Imaging Reporting and Data System (BI-RADS), and women self-reported their physical activity level over the past year. ORs were estimated using logistic generalized estimating equations after adjusting for age, body mass index, menopausal status, parity, family history of breast or ovarian cancer, hormone therapy use, smoking status, alcohol consumption, and year.

RESULTS

We observed inverse associations of physical activity with dense breasts. Adjusted ORs were 0.96 (95% confidence interval: 0.91-1.00) for women with physical exercise for 1-2 days per week, 0.94 (0.88-0.99) for those with physical exercise for 3-5 days per week, and 0.91 (0.84-0.99) for those with daily physical exercise when compared with those reported seldom physical exercise.

CONCLUSIONS

Higher levels of physical activity may be associated with decreased mammographic density levels in Japanese women.

IMPACT

Increasing physical activity may serve as a reasonable intervention to reduce mammographic density, and thereby, to mitigate the risk of breast cancer in Asian women.

Evaluating the relationship between physical activity and quality of life in a racially diverse sample of breast cancer survivors

PURPOSE

Physical activity (PA) has been shown to improve quality of life (QoL) in predominantly White cancer survivors. Very few studies have examined the association between PA and QoL among Black breast cancer survivors (BCS). We investigated the association between PA and multiple QoL domains and the effects of race on the proposed association in a racially diverse group of BCS.

METHODS

This was an exploratory study using secondary data from a completed 12-month randomized controlled  trial (RCT). Mixed effects models were tested on a subset of participants in the control and exercise groups of the RCT. The primary outcomes were changes in the QoL domains (baseline to 12 months post baseline).

RESULTS

There were 173 participants included in this analysis, averaging 59 years of age; about 33% of the participants were Black women. There were no significant differences in the QoL outcomes between the control and exercise groups at 12 months post baseline. Race was not a significant moderator. Exercise improved emotional/mental wellbeing and body image as it relates to social barriers at 12 months post baseline in Black and White BCS, but the changes in these outcomes were only statistically significant in White BCS (p < 0.05).

CONCLUSIONS

Results show that exercise can improve multiple QoL domains over time in Black BCS. However, the significance of the effect on QoL was isolated to White BCS. The small sample size in Black women could constrain the statistical significance of observed effects. Future studies are warranted to assess associations between exercise and QoL in larger samples of Black women.

Association between estimated cardiorespiratory fitness and breast cancer: a prospective cohort study

OBJECTIVE

To examine the association between cardiorespiratory fitness (CRF) and the risk of breast cancer in postmenopausal women.

METHODS

This study used data from 17 840 cancer-free postmenopausal women with a CRF assessment from the UK Biobank. High estimated CRF (eCRF) was categorised as being >80th percentile within 10-year age bands. Fine and Gray regression was used to examine the association between eCRF and breast cancer risk, accounting for both non-breast cancer diagnoses and all-cause mortality as competing risks. Age was used as the time scale. Several different models were produced, including those adjusting for known breast cancer risk factors, and stratified by measures of body fat (body mass index and per cent body fat).

RESULTS

Over a median follow-up of 11.0 years there were 529 cases of invasive breast cancer, 1623 cases of non-breast cancer disease and 241 deaths. With adjustment for breast cancer risk factors, high eCRF was associated with a 24% (subdistribution HR (SDHR) 0.76, 95% CI 0.60 to 0.97) lower risk of breast cancer. When stratified by measures of body fat, we found evidence of effect measure modification. Mainly, having high eCRF was only associated with a lower risk of breast cancer among those classified as having overweight/obesity (SDHR 0.33, 95% CI 0.11 to 1.01) or percentage body fat above the 1st quintile (SDHR 0.65, 95% CI 0.45 to 0.94).

CONCLUSION

Having higher CRF may be a protective factor against breast cancer in postmenopausal women but only for women with elevated body fat.

Prevalence, trend and associated factors of obesity-related cancers among U.S. adults with metabolic syndrome: Evidence from the National Health and Nutrition Examination Survey 2001-2018

INTRODUCTION

This study evaluated the prevalence, associated factors and trends in the prevalence of obesity-related cancer (ORC) among U.S. adults with metabolic syndrome (MetS) and age ≥20 years.

METHODS

This study used cross-sectional data from the 2001-2018 National Health and Nutrition Examination Survey. The total period analyses included prevalence estimation, chi-square tests for comparing ORC vs non-ORC within subgroups, and a multivariable-logistic regression model to evaluate associated factors of ORC. For trend analysis, the total period was divided into three time periods: 2001-2006, 2007-2012 and 2013-2018. Age-standardized prevalence of ORC in each time period was calculated.

RESULTS

The ORC prevalence was 35.8% representing 4463614 adults with MetS. A higher odds of ORC was observed among females (OR = 7.1, 95% CI = 4.9-10.3) vs males, Hispanic (OR = 2.9, 95% CI = 1.7-4.8) and non-Hispanic Black (OR = 2.7, 95% CI = 1.8-4) vs non-Hispanic White, age ≥60 (OR = 5.4, 95% CI = 1.9-15.4) vs age 20-39 years. Individual ORCs were thyroid (10.95%), breast (10%), uterine (9.18%), colorectal (7.86%), ovarian (5.74%), and stomach (0.80%). The age-standardized prevalence of ORC was observed stable in three time periods (30.6%, 30.3% and 30.7%). However, an increasing trend was seen for thyroid, uterine, colorectal and ovarian cancers while decreasing trend for breast cancer. Hispanic people showed a significant increasing trend of ORC (p = 0.004).

CONCLUSIONS

ORC was found significantly higher among female, Hispanic, non-Hispanic black and older people with MetS. The stable temporal trend of overall ORC, with an increasing trend in certain ORCs, makes the disease spectrum a public health priority. The findings imply the importance of intensifying efforts to reduce the burden of MetS comorbidities among U.S. adults.

A review of the impact of energy balance on triple-negative breast cancer

Cancer cells cannot proliferate without sufficient energy to generate biomass for rapid cell division, as well as to fuel their functions at baseline. For this reason, many recent observational and interventional studies have focused on increasing energy expenditure and/or reducing energy intake during and after cancer treatment. The impact of variance in diet composition and in exercise on cancer outcomes has been detailed extensively elsewhere and is not the primary focus of this review. Instead, in this translational, narrative review we examine studies of how energy balance impacts anticancer immune activation and outcomes in triple-negative breast cancer (TNBC). We discuss preclinical, clinical observational, and the few clinical interventional studies on energy balance in TNBC. We advocate for the implementation of clinical studies to examine how optimizing energy balance-through changes in diet and/or exercise-may optimize the response to immunotherapy in people with TNBC. It is our conviction that by taking a holistic approach that includes energy balance as a key factor to be considered during and after treatment, cancer care may be optimized, and the detrimental effects of cancer treatment and recovery on overall health may be minimized.

The Benefits of Exercise in Breast Cancer

Breast cancer is the most prevalent cancer among women, accounting for nearly 30% of all cancers, while in men, it represents only 1% of cases. Breast cancer is the main cause of death for cancer, and its incidence and mortality vary according to patients' ethnicity, geographic region, and socioeconomic status. Due to the low prevalence of breast cancer among men and the scarcity of studies in the literature, exercises have been prescribed based on extrapolations from studies on female patients. Scientific evidence has suggested beneficial effects of physical exercises on breast cancer prevention, treatment, and post-treatment. In addition to combatting sedentary behavior, it is essential to maintain a healthy body weight, limit alcohol consumption, and follow a balanced diet, rich in fruit, vegetables, grains and fibers, and limited in red meat. The effects of exercises are not restricted to breast cancer, but extend to controlling modifiable risk factors, and reducing the incidence of cardiovascular diseases, and all-cause and cardiovascular mortality.

Multivariate analysis of independent roles of socioeconomic status, occupational physical activity, reproductive factors, and postmenopausal hormonal therapy in risk of breast cancer

PURPOSE

This case-control study assesses the independent roles of reproductive history, postmenopausal hormonal therapy (HT), socioeconomic status (SES), and occupational physical activity on the risk of breast cancer (BC).

METHODS

Odds ratios (OR) were estimated from conditional logistic multivariate regression model in a data set of 19,253 Finnish women diagnosed with BC between 1994 and 2013 and 96,265 age-matched population controls.

RESULTS

Both pre- and postmenopausal white-collar workers had significantly increased risk of ductal and lobular BC as compared to manual workers. Moderate occupational physical activity reduced risk of lobular BC by 14%. There was a transient increase in the risk of BC observed after each birth followed by a protective effect starting some years after the delivery. As the number of children increased, the short-term excess risk was lower and protective effect was observed earlier. Continuous estrogen-progestin therapy (EPT) significantly increased the risk of both ductal and lobular BC and the magnitude of risk was directly proportional to duration of use (OR for 5+ years of use 2.26, 95% confidence interval 2.12-2.42). Monthly EPT for 5+ years increased the risk (OR 1.32, 95% CI 1.20-1.45). Users of estradiol plus levonorgestrel intrauterine system devices showed ORs of 1.56 (95% CI 1.45-1.69) and 2.18 (95% CI 1.81-2.64) for ductal and lobular BC, respectively.

CONCLUSION

This study concludes that pregnancy has a dual effect on BC risk, with a transient increase in risk followed by a long-term protective effect. The SES and HT have a large effect on BC risk while occupational physical activity has only a small independent effect.

Physical activity and risk of benign proliferative epithelial disorders of the breast, in the Women's Health Initiative

BACKGROUND

Recreational physical activity (PA) has been shown to be inversely associated with breast cancer risk. However, the association of recreational PA with benign proliferative epithelial disorders (BPED) of the breast, conditions associated with increased risk of breast cancer, has not been adequately studied.

METHODS

We used data from an ancillary study of benign breast disease conducted among the 68 132 postmenopausal women (aged 50-79 at recruitment) participating in the Women's Health Initiative randomized clinical trials. All clinical trial participants underwent annual or biennial mammogram screening. During the follow-up, for women who reported breast biopsies but were cancer free, the associated histological sections were obtained and subjected to standardized central pathology review. Self-reported recreational PA at baseline (n = 61 684) and at 3 years of the follow-up (n = 55 923) were quantified as metabolic equivalents [MET]-h/week. There were 1624 confirmed BPED cases during an average follow-up time of 7.7 years. Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs).

RESULTS

Higher average PA over 4 years was associated with lower risk of non-atypical BPED (P-trend = 0.02). There was a 6% lower risk of non-atypical BPED for every 5 MET-h/week increase between baseline and year 3 (HR = 0.94, 95% CI 0.89-0.99). Compared with women who remained inactive (PAbaseline and PAyear3 <9 MET-h/week), those who became active (PAbaseline<9 MET-h/week to PAyear3 ≥9 MET-h/weekee), remained active (PAbaseline and PAyear3 ≥9 MET-h/week), or decreased activity (PAbaseline ≥9 MET-h/week to PAyear3 <9 MET-h/week) had lower BPED risk.

CONCLUSIONS

Recreational physical activity after menopause was associated with lower BPED risk among postmenopausal women.

Aerobic Exercise Training and In Vivo Akt Activation Counteract Cancer Cachexia by Inducing a Hypertrophic Profile through eIF-2α Modulation

Simple Summary

Chronic disease-related muscle atrophy is a serious public health problem since it reduces mobility and contributes to increases in hospitalization costs. Unfortunately, there is no approved treatment for muscle wasting at present. Thus, an understanding of the mechanisms underlying the control of muscle mass and function under chronic diseases can pave the way for the discovery of innovative therapeutic strategies to counteract muscle wasting. Since numerous types of cancer induce cachexia, which has no cure nor an effective treatment, the main proposal here was to study the effects of AET in cancer cachexia, and to investigate, through in vivo manipulation of the Akt/mTORC1 pathway, whether the cachectic muscle still presents conditions to respond adaptively to hypertrophic stimuli. Our results could provide a basis for innovative research lines to better understand muscle plasticity and to investigate potential therapeutic approaches necessary to prevent muscle loss.

Abstract

Cancer cachexia is a multifactorial and devastating syndrome characterized by severe skeletal muscle mass loss and dysfunction. As cachexia still has neither a cure nor an effective treatment, better understanding of skeletal muscle plasticity in the context of cancer is of great importance. Although aerobic exercise training (AET) has been shown as an important complementary therapy for chronic diseases and associated comorbidities, the impact of AET on skeletal muscle mass maintenance during cancer progression has not been well documented yet. Here, we show that previous AET induced a protective mechanism against tumor-induced muscle wasting by modulating the Akt/mTORC1 signaling and eukaryotic initiation factors, specifically eIF2-α. Thereafter, it was determined whether the in vivo Akt activation would induce a hypertrophic profile in cachectic muscles. As observed for the first time, Akt-induced hypertrophy was able and sufficient to either prevent or revert cancer cachexia by modulating both Akt/mTORC1 pathway and the eIF-2α activation, and induced a better muscle functionality. These findings provide evidence that skeletal muscle tissue still preserves hypertrophic potential to be stimulated by either AET or gene therapy to counteract cancer cachexia.

Recreational Physical Activity and Outcomes After Breast Cancer in Women at High Familial Risk

Background

Recreational physical activity (RPA) is associated with improved survival after breast cancer (BC) in average-risk women, but evidence is limited for women who are at increased familial risk because of a BC family history or BRCA1 and BRCA2 pathogenic variants (BRCA1/2 PVs).

Methods

We estimated associations of RPA (self-reported average hours per week within 3 years of BC diagnosis) with all-cause mortality and second BC events (recurrence or new primary) after first invasive BC in women in the Prospective Family Study Cohort (n = 4610, diagnosed 1993-2011, aged 22-79 years at diagnosis). We fitted Cox proportional hazards regression models adjusted for age at diagnosis, demographics, and lifestyle factors. We tested for multiplicative interactions (Wald test statistic for cross-product terms) and additive interactions (relative excess risk due to interaction) by age at diagnosis, body mass index, estrogen receptor status, stage at diagnosis, BRCA1/2 PVs, and familial risk score estimated from multigenerational pedigree data. Statistical tests were 2-sided.

Results

We observed 1212 deaths and 473 second BC events over a median follow-up from study enrollment of 11.0 and 10.5 years, respectively. After adjusting for covariates, RPA (any vs none) was associated with lower all-cause mortality of 16.1% (95% confidence interval [CI] = 2.4% to 27.9%) overall, 11.8% (95% CI = -3.6% to 24.9%) in women without BRCA1/2 PVs, and 47.5% (95% CI = 17.4% to 66.6%) in women with BRCA1/2 PVs (RPA*BRCA1/2 multiplicative interaction P = .005; relative excess risk due to interaction = 0.87, 95% CI = 0.01 to 1.74). RPA was not associated with risk of second BC events.

Conclusion

Findings support that RPA is associated with lower all-cause mortality in women with BC, particularly in women with BRCA1/2 PVs.

Physiotherapy and Physical Activity as Factors Improving the Psychological State of Patients With Cancer

Physiotherapy in oncology is a process closely related to cancer treatment methods. Rehabilitation is based on physical activity in various forms involving the musculoskeletal system but also affects the emotional state. Physical activity influences physical and psychological well-being of people undergoing oncological treatment, in the course of which the most common psychiatric disorders are depression, substance use disorder, sleep disorders, fatigue syndrome, resulting in worsening of the quality of life. Difficulties in implementing physical exercise in cancer patients pose a challenge to treatment teams.

A Review of Modifiable Risk Factors in Young Women for the Prevention of Breast Cancer

Breast cancer is the most common cancer diagnosis in women aged less than 40 years and the second most common cause of cancer death in this age group. Global rates of young onset breast cancer have risen steadily over the last twenty years. Although young women with breast cancer have a higher frequency of underlying pathogenic mutations in high penetrance breast cancer susceptibility genes (CSG) than older women, the vast majority of young breast cancer patients are not found to have a germline CSG mutation. There is therefore a need to inform young women regarding non-genetic breast cancer risk factors which have the potential to be influenced by changes in individual behaviour. A Pubmed search was performed using the search terms “young” or “early onset”, and “breast cancer” and “modifiable risk”. Titles and abstracts from peer-reviewed publications were screened for relevance. This review presents evidence for potentially modifiable risk factors of breast cancer risk in young women, including lifestyle factors (physical activity, body habitus, alcohol use, smoking, shift work and socioeconomic factors), reproductive and hormonal factors and iatrogenic risks. The extent to which these factors are truly modifiable is discussed and interactions between genetic and non-genetic risk factors are also addressed. Health care professionals have an opportunity to inform young women about breast health and risk when presenting at a “teachable moment”, including the benefits of physical activity and alcohol habits as risk factor. More focussed discussions regarding individual personal risk and benefit should accompany conversations regarding reproductive health and take into consideration both non-modifiable and iatrogenic BC risk factors.

Prevalence and predictors of obesity-related cancers among racial/ethnic groups with metabolic syndrome

Background

Obesity-related cancer (ORC) is associated with higher amounts of body fat, which could increase the risk of developing cardiovascular disease (CVD). A significant factor associated with CVD is metabolic syndrome (MetS), and MetS prevalence differs by race/ethnicity. The purpose of this study was to compare the prevalence and predictors of ORCs by race/ethnicity among adults (>18) with MetS.

Methods

This was a retrospective, cross-sectional study using data from the 1999–2014 National Health and Nutrition Examination Survey (NHANES). A chi-square test was performed to determine differences in ORC prevalence between non-Hispanic White (NHW), non-Hispanic Black (NHB), and Hispanic participants with MetS. A multivariate logistic regression was used to evaluate predictors (race, sex, income, insurance, education, marital status, and smoking status) of ORC among adults with MetS.

Results

Of the 1,554 adults, the prevalence of ORC was 30.6% among NHWs, 51.3% in NHBs, and 54.1% in Hispanics (p = <0.001). Females were 6.27 times more likely to have an ORC compared to males (95% CI = 4.95–14.11). Compared to NHWs, NHBs were 2.1 times more likely to have an ORC (95% CI = 1.40–3.38); and Hispanics were 2.5 times more likely (95% CI = 1.39–4.77). For every 1-year unit increase in age, the odds of ORC increased by 3% (95% CI = 1.00–1.05).

Conclusions

Among NHANES participants with MetS, the prevalence of ORCs was significantly higher in NHBs and Hispanics, females, and older adults with MetS. Future studies, by race/ethnicity, are warranted on mortality risk of persons with MetS and ORC.

Effect of time of day of recreational and household physical activity on prostate and breast cancer risk (MCC-Spain study)

Experimental evidence indicates that exercise performed at different times of the day may affect circadian rhythms and circadian disruption has been linked to breast and prostate cancer. We examined in a population-based case-control study (MCC-Spain) if the time-of-day when physical activity is done affects prostate and breast cancer risk. Lifetime recreational and household physical activity was assessed by in-person interviews. Information on time-of-day of activity (assessed approximately 3 years after the assessment of lifetime physical activity and confounders) was available for 781 breast cancer cases, 865 population female controls, 504 prostate cases and 645 population male controls from 10 Spanish regions, 2008-2013. We estimated odds ratios (ORs) and 95% confidence intervals (95% CI) for different activity timings compared to inactive subjects using unconditional logistic regression adjusting for confounders. Early morning (8-10 am) activity was associated with a protective effect compared to no physical activity for both breast (OR = 0.74, 95% CI = 0.48-1.15) and prostate cancer (OR = 0.73, 95% CI = 0.44-1.20); meta-OR for the two cancers combined 0.74 (95%CI = 0.53-1.02). There was no effect observed for breast or prostate cancer for late morning to afternoon activity while a protective effect was also observed for evening activity only for prostate cancer (OR = 0.75, 95% CI = 0.45-1.24). Protective effects of early morning activity were more pronounced for intermediate/evening chronotypes for both cancers. This is the first population-based investigation identifying a differential effect of timing of physical activity on cancer risk with more pronounced effects for morning hour activity. Our results, if confirmed, may improve current physical activity recommendations for cancer prevention.

Dancing With Health: Quality of Life and Physical Improvements From an EU Collaborative Dance Programme With Women Following Breast Cancer Treatment

Background: Women's health has received renewed attention in the last few years including health rehabilitation options for women affected by breast cancer. Dancing has often been regarded as one attractive option for supporting women's well-being and health, but research with women recovering from breast cancer is still in its infancy. Dancing with Health is multi-site pilot study that aimed to evaluate a dance programme for women in recovery from breast cancer across five European countries.

Methods: A standardized 32 h dance protocol introduced a range of Latin American dances presented within a sports and exercise framework with influences from dance movement therapy. Fifty-four women (M age 53.51; SD 7.99) participated in the study who had a breast cancer diagnosis <3 years, chemotherapy >6 weeks, no indication of metastasis, or scheduled surgery/chemotherapy/radiation treatment for the duration of the intervention. Primary outcome data was collected for anthropometric and fitness measures next to cancer-related quality of life. T-tests and Wilcoxon signed ranked tests were used to establish differences pre and post intervention. Cohen's d was also calculated to determine the effect size of the intervention.

Results: Statistically significant changes were found for: (i) weight, right and left forearm circumference and hip; (ii) 6 min walking, right and left handgrip, sit-to-stand and sit-and-reach; (iii) the EORTC-QLQ C30 summary score as well as the subscales of emotional and social functioning and symptoms. In all cases the direction of change was positive, while Cohen's d calculated showed that the effect of the intervention for these parameters ranged from intermediate to large.

Conclusion: Changes on the above anthropometric, fitness and quality of life measures suggest that the intervention was of value to the participating women recovering from breast cancer. Results also advocate collaborative efforts across countries to further research.

Physical Activity and Breast Cancer: A Case-Control Study in Southern Brazil

Physical inactivity is one of the greatest public health challenges in the 21st century. More than five million deaths a year are caused by lack of physical activity (PA) around the world. Despite its relevance to public health, about one-third of the world's adults do not meet current PA recommendations for health benefits. Thus, the aim of the present study was to investigate the association between lifetime PA and risk of breast cancer. A case-control study was conducted between November 2016 and June 2017. The cases were recruited from all cancer centers in the city of Pelotas in southern Brazil. Each case was age-matched (±5 years) with a neighborhood control enrolled based on nearby addresses of the cases. Overall, 230 cases and 231 controls were included. Lifetime leisure-time PA may decrease the odds of breast cancer (adjusted OR = 0.44; 95%CI 0.23-0.86) in the comparison between the most active with the least active quartile. PA was associated with a reduction in the odds of breast cancer. Future studies should aim at understanding the physiological pathways that could explain how an active lifestyle influences this disease, helping in the establishment of volume and intensities necessary to obtain the benefits.

Hymenolepis diminuta-based helminth therapy in C3(1)-TAg mice does not alter breast tumor onset or progression

Background and objectives

An individual's risk of breast cancer is profoundly affected by evolutionary mismatch. Mismatches in Western society known to increase the risk of breast cancer include a sedentary lifestyle and reproductive factors. Biota alteration, characterized by a loss of biodiversity from the ecosystem of the human body as a result of Western society, is a mismatch known to increase the risk of a variety of inflammation-related diseases, including colitis-associated colon cancer. However, the effect of biota alteration on breast cancer has not been evaluated.

Methodology

In this study, we utilized the C3(1)-TAg mouse model of breast cancer to evaluate the role of biota alteration in the development of breast cancer. This model has been used to recapitulate the role of exercise and pregnancy in reducing the risk of breast cancer. C3(1)-TAg mice were treated with Hymenolepis diminuta, a benign helminth that has been shown to reverse the effects of biota alteration in animal models.

Results

No effect of the helminth H. diminuta was observed. Neither the latency nor tumor growth was affected by the therapy, and no significant effects on tumor transcriptome were observed based on RNAseq analysis.

Conclusions and implications

These findings suggest that biota alteration, although known to affect a variety of Western-associated diseases, might not be a significant factor in the high rate of breast cancer observed in Western societies.

Lay summary

An almost complete loss of intestinal worms in high-income countries has led to increases in allergic disorders, autoimmune conditions, and perhaps colon cancer. However, in this study, results using laboratory mice suggest that loss of intestinal worms might not be associated with breast cancer.

Impact of Lifestyle Behaviors on Cancer Risk and Prevention

Cancer incidences are rising globally. Therefore, in order to prevent and treat cancer, understanding cancer pathology is crucial. Tumors reprogram their metabolic phenotype to meet their needs for bioenergy, biosynthesis, and redox control. Alteration of the metabolic pathway has been proposed as the hallmark of cancer and explains the distinction between normal and cancer cells concerning nutrient utilization. Changes in the metabolism of nutrients such as glucose, amino acid, and fatty acid are associated with cancer risk. Luckily, this can be controlled with lifestyle modifications. Improvements in lifestyle behaviors to reduce cancer risks include a healthy diet, calorie restriction, and regular physical activity. This review begins with the understandings of metabolic reprogramming in cancer. Then, there will be evidence on the correlation between lifestyle factors and altered nutrient metabolism suggesting an application of lifestyle intervention for cancer risk reduction.

Physical activity and cancer risk. Actual knowledge and possible biological mechanisms

Background

Scientific evidence has shown that an increase in regular physical activity is associated with a decrease in the development of many types of cancer. Potential mechanisms that link physical activity to reduced cancer risk include a decrease in systemic inflammation, hyperinsulinemia, insulin-like growth factor (IGF-I), sex hormones, pro-inflammatory leptin and other obesity-related cytokines, and a significant increase in anti-inflammatory adiponectin levels. In addition, physical activity improves immune function and the composition and diversity of the gastrointestinal microbiota. Moderate physical activity is important for cancer protection, but the most significant changes in the inflammatory profile are conferred by physical activity performed at higher intensities. Thus, there is a need for further investigation into the type, intensity, and duration of physical activity for the prevention of some types of cancer and the development of effective recommendations.

Conclusions

There is a strong evidence that physical activity of moderate to vigorous intensity protects against colon and breast cancer, and probably against cancer at all other sites.

Endurance Exercise Mitigates Immunometabolic Adipose Tissue Disturbances in Cancer and Obesity

Adipose tissue is considered an endocrine organ whose complex biology can be explained by the diversity of cell types that compose this tissue. The immune cells found in the stromal portion of adipose tissue play an important role on the modulation of inflammation by adipocytokines secretion. The interactions between metabolic active tissues and immune cells, called immunometabolism, is an important field for discovering new pathways and approaches to treat immunometabolic diseases, such as obesity and cancer. Moreover, physical exercise is widely known as a tool for prevention and adjuvant treatment on metabolic diseases. More specifically, aerobic exercise training is able to increase the energy expenditure, reduce the nutrition overload and modify the profile of adipocytokines and myokines with paracrine and endocrine effects. Therefore, our aim in this review was to cover the effects of aerobic exercise training on the immunometabolism of adipose tissue in obesity and cancer, focusing on the exercise-related modification on adipose tissue or immune cells isolated as well as their interaction.

Physical activity barriers and resources among black women with a history of breast and endometrial cancer: a systematic review

Physical inactivity is a significant public health problem among black women. However, there is limited evidence regarding barriers to physical activity and the availability of opportunities to engage in physical activity, specifically for posttreatment black women with a history of cancer.

PURPOSE

The purpose of this paper was to systematically review, summarize, and synthesize findings on physical activity-related research including barriers, facilitators, and resources for physical activity among posttreatment black women with a history of breast and endometrial cancer.

METHODS

We developed a comprehensive search strategy and conducted searches in the following databases: PsycINFO, Web of Science, Cochrane, PubMed, and Sociological Abstracts. Summary measures were described qualitatively (e.g., themes) and quantitatively (e.g., frequencies).

RESULTS

This review identified 35 eligible articles describing 12 intervention and 23 observational studies. We described intervention preferences (e.g., resistance activities), beliefs about physical activity, and benefits of physical activity for quality of life (e.g., improvements in social wellbeing) in black cancer survivors. In addition, very few studies identified barriers to physical activity (n = 7) and focused on increasing physical activity (n = 12) among black women with a history of cancer. The most common reported barriers among the target population were fatigue, lack of social support, weather, illness/health issues, cost, time constraints, living too far away, and inability/unwillingness to obtain physician clearance, whereas the most common facilitators were faith, other health concerns, and social support.

CONCLUSIONS/IMPLICATIONS

Future studies should target barriers, facilitators, and culturally adapted strategies for physical activity at all levels of influence to develop multi-level interventions to engage and improve physical activity among black women with a history of breast and endometrial cancer.

PROTOCOL REGISTRATION NUMBER

CRD42018110008.

Association of physical activity, body mass index and reproductive history with breast cancer by menopausal status in Iranian women

BACKGROUND

The incidence rate of breast cancer (BC) is increasing in low- and middle-income countries (LMICs), including Iran. We investigated the association between BC risk and physical activity (PA), body mass index (BMI), and reproductive history among Iranian women.

METHODS

We conducted a large hospital-based case-control study and compared 958 BC cases with 967 controls at the Cancer Institute of Iran during 2011-2016. We used multiple logistic regression models and adjusted for potential confounders to estimate odds ratios (ORs) and 95% confidence intervals (95%CIs) for the associations between BC and different risk factors, including low physical activity.

RESULTS

Women with high levels of physical activity had a lower risk of BC compared to those who were inactive (OR = 0.55, 95%CI: 0.41, 0.75). In premenopausal women, the association was observed only in normal-weight women (OR = 0.31, 95%CI: 0.13, 0.75), while it was limited to obese women in the postmenopausal group (OR = 0.29, 95%CI: 0.12, 0.66). We found a high risk of postmenopausal BC among overweight (OR = 1.69; 95%CI: 1.01, 2.81) and obese women (OR = 1.9; 95%CI: 1.14, 3.14) compared to women with a normal BMI. We observed an inverse association among postmenopausal women who had between three and five children (OR = 0.31, 95%CI 0.14, 0.64) and more than six children (OR = 0.21, 95%CI 0.12, 0.42) compared to nulliparous women.

CONCLUSIONS

Low levels of physical activity, low parity, and being overweight or obese were major risk factors for BC. For the first time, we report a strong association between physical activity and BC risk in Iranian women.

Prevention and adherence in Rheumatic and Musculoskeletal disease

Rheumatic and Musculoskeletal Diseases (RMDs) are chronic conditions that affect a substantial number of people. RMDs are significantly related to co-morbidity. Therefore, focusing on prevention in RMDs is of importance to promote and maintain health. Prevention includes primary-, secondary-, tertiary-, and clinical prevention. Primary prevention aims to prevent the onset of disease before the disease process begins, secondary prevention includes detecting and reducing disease and risk factors at the earliest possible point, and tertiary prevention aims to limit the influence of a recognized or verified disease and to address or reduce further development or worsening of the disease, including physical and psychosocial disability. Clinical prevention attempts to integrate prevention into the disease management to limit disease progression and prevent complications and relapse. This chapter will focus on the evidence for prevention and highlight how innovations and trends can contribute by using digital technologies as an example.

Physical activity and breast cancer risk: results from the UK Biobank prospective cohort

BACKGROUND

Previous studies suggest a protective role of physical activity in breast cancer risk, largely based on self-reported activity. We aimed to clarify this association by examining breast cancer risk in relation to self-reported physical activity, informed by accelerometer-based measures in a large subset of participants.

METHODS

We analysed data from 47,456 premenopausal and 126,704 postmenopausal women in UK Biobank followed from 2006 to 2014. Physical activity was self-reported at baseline, and at resurvey in a subsample of 6443 participants. Accelerometer data, measured from 2013 to 2015, were available in 20,785 women. Relative risks (RRs) and 95% confidence intervals (CIs) were calculated by using multivariable-adjusted Cox regression.

RESULTS

A total of 3189 cases were diagnosed during follow-up (mean = 5.7 years). Women in the top compared with the bottom quartile of self-reported physical activity had a reduced risk of both premenopausal (RR 0.75; 95% CI 0.60-0.93) and postmenopausal breast cancer (RR 0.87; 95% CI 0.78-0.98), after adjusting for adiposity. In analyses utilising physical activity values assigned from accelerometer measurements, an increase of 5 milli-gravity was associated with a 21% (RR 0.79; 95% CI 0.66-0.95) reduction in premenopausal and a 16% (RR 0.84; 95% CI 0.73-0.96) reduction in postmenopausal breast cancer risk.

CONCLUSIONS

Greater physical activity is associated with a reduction in breast cancer risk, which appears to be independent of any association it may have on risk through its effects on adiposity.

Exercise Training Results in Lower Amyloid Plaque Load and Greater Cognitive Function in an Intensity Dependent Manner in the Tg2576 Mouse Model of Alzheimer's Disease

Three months of exercise training (ET) decreases soluble Aβ₄₀ and Aβ₄₂ levels in an intensity dependent manner early in life in Tg2576 mice (Moore et al., 2016). Here, we examined the effects of 12 months of low- and high- intensity exercise training on cognitive function and amyloid plaque load in the cortex and hippocampus of 15-month-old Tg2576 mice. Low- (LOW) and high- (HI) intensity ET animals ran at speeds of 15 m/min on a level treadmill and 32 m/min at a 10% grade, respectively, for 60 min/day, five days/week, from 3 to 15 months of age. Sedentary mice (SED) were placed on a level, non-moving, treadmill for the same duration. ET mice demonstrated a significantly lower amyloid plaque load in the cortex and hippocampus that was intensity dependent. Improvement in cognitive function, assessed by Morris Water Maze and Novel Object Recognition tests, was greater in the HI group compared to the LOW and SED groups. LOW mice performed better in the initial latency to the platform location during the probe trial of the Morris Water Maze (MWM) test than SED, but not in any other aspect of MWM or the Novel Object Recognition test. The results of this study indicate that exercise training decreases amyloid plaque load in an intensity dependent manner and that high-intensity exercise training improves cognitive function relative to SED mice, but the intensity of the LOW group was below the threshold to demonstrate robust improvement in cognitive function in Tg2576 mice.

Association of Diet Quality and Physical Activity on Obesity-Related Cancer Risk and Mortality in Black Women: Results from the Women's Health Initiative

BACKGROUND

Obesity-related cancers disproportionately affect the Black community. We assessed the relationship between diet quality, physical activity, and their combined effect on obesity-related cancer risk and mortality in Black women enrolled in the Women's Health Initiative (WHI).

METHODS

Data from postmenopausal (50-79 years of age) Black women enrolled in WHI clinical trials or observational studies were analyzed. Exposure variables included baseline physical activity [metabolic equivalent of tasks (MET)-hours/week of moderate-to-vigorous physical activity (MVPA)] and diet quality [Healthy Eating Index (HEI)-2015]. Outcomes included adjudicated obesity-related cancer incidence and mortality. Cox proportional hazard models were used to evaluate the association between MVPA and HEI-2015 and obesity-related cancer risk and mortality.

RESULTS

The analytical sample included 9,886 Black women, with a baseline mean body mass index (BMI) of 31.1 kg/m² (SD = 6.8); mean HEI-2015 score of 63.2 (SD = 11.0, possible range 0 to 100); and mean MVPA of 5.0 (SD = 9.4) MET-hours/week. Over an average of 13 years of follow-up, 950 (9.6%) obesity-related cancer cases were observed, with 313 (32.9%) resulting in death. Physical activity [HR, 1.05; 95% confidence interval (CI), 0.86-1.30], diet quality (HR, 0.99; 95% CI, 0.92-1.08), and their combination (HR, 1.05; 95% CI, 0.85-1.29) were not associated with risk for any or site-specific obesity-related cancers. Similarly, these health behaviors had no association with mortality.

CONCLUSIONS

Diet quality, physical activity and their combined effect, as measured, were not associated with obesity-related cancer risk and mortality in Black women enrolled in WHI.

IMPACT

Other social, behavioral, and biological factors may contribute to racial disparities observed in obesity-related cancer rates.

Recreational Physical Activity Is Associated with Reduced Breast Cancer Risk in Adult Women at High Risk for Breast Cancer: A Cohort Study of Women Selected for Familial and Genetic Risk

Although physical activity is associated with lower breast cancer risk for average-risk women, it is not known if this association applies to women at high familial/genetic risk. We examined the association of recreational physical activity (self-reported by questionnaire) with breast cancer risk using the Prospective Family Study Cohort, which is enriched with women who have a breast cancer family history (N = 15,550). We examined associations of adult and adolescent recreational physical activity (quintiles of age-adjusted total metabolic equivalents per week) with breast cancer risk using multivariable Cox proportional hazards regression, adjusted for demographics, lifestyle factors, and body mass index. We tested for multiplicative interactions of physical activity with predicted absolute breast cancer familial risk based on pedigree data and with BRCA1 and BRCA2 mutation status. Baseline recreational physical activity level in the highest four quintiles compared with the lowest quintile was associated with a 20% lower breast cancer risk (HR, 0.80; 95% confidence interval, 0.68-0.93). The association was not modified by familial risk or BRCA mutation status (P interactions >0.05). No overall association was found for adolescent recreational physical activity. Recreational physical activity in adulthood may lower breast cancer risk for women across the spectrum of familial risk. SIGNIFICANCE: These findings suggest that physical activity might reduce breast cancer risk by about 20% for women across the risk continuum, including women at higher-than-average risk due to their family history or genetic susceptibility.See related commentary by Niehoff et al., p. 23.

The iReAct study - A biopsychosocial analysis of the individual response to physical activity

Background

Physical activity is a substantial promoter for health and well-being. Yet, while an increasing number of studies shows that the responsiveness to physical activity is highly individual, most studies focus this issue from only one perspective and neglect other contributing aspects. In reference to a biopsychosocial framework, the goal of our study is to examine how physically inactive individuals respond to two distinct standardized endurance trainings on various levels. Based on an assessment of activity- and health-related biographical experiences across the life course, our mixed-method study analyzes the responsiveness to physical activity in the form of a transdisciplinary approach, considering physiological, epigenetic, motivational, affective, and body image-related aspects.

Methods

Participants are randomly assigned to two different training programs (High Intensity Interval Training vs. Moderate Intensity Continuous Training) for six weeks. After this first training period, participants switch training modes according to a two-period sequential-training-intervention (STI) design and train for another six weeks. In order to analyse baseline characteristics as well as acute and adaptive biopsychosocial responses, three extensive mixed-methods diagnostic blocks take place at the beginning (t₀) of the study and after the first (t₁) and the second (t₂) training period resulting in a net follow-up time of 15 weeks. The study is divided into five modules in order to cover a wide array of perspectives.

Discussion

The study's transdisciplinary mixed-method design allows to interlace a multitude of subjective and objective data and therefore to draw an integrated picture of the biopsychosocial efficacy of two distinct physical activity programs. The results of our study can be expected to contribute to the development and design of individualised training programs for the promotion of physical activity.

Trial registration

The study was retrospectively registered in the German Clinical Trials Register on 12 June 2019 (DRKS00017446).

Determinants of breast cancer in Saudi women from Makkah region: a case-control study (breast cancer risk factors among Saudi women)

Background

There are various factors that play a major role in influencing the overall health conditions of women diagnosed with breast cancer. The population of women in Makkah region are diverse, therefore it is significant to highlight the possible determinants of breast cancer in this population. This is a case-control study that assessed determinants of breast cancer including socioeconomic factors, health-related characteristics, menstrual histories and breastfeeding among postmenopausal women in Makkah region in Saudi Arabia.

Methods

A total of 432 female participants (214 cases and 218 controls) were recruited for this study. A validated questionnaire was completed by trained dietitians at King Abdullah Medical City Hospital in the Makkah region of Saudi Arabia.

Results

Results displayed that determinants of breast cancer were associated significantly (P < 0.05) with unemployment, large family size, lack of knowledge and awareness about breast cancer, obesity, sedentary lifestyle, smoking, starting menarche at an early age, as well as hormonal and non-hormonal contraceptive use. There was no effect of diabetes, hypertension, hyperlipidemia, and duration of breastfeeding on the incidence of breast cancer.

Conclusion

In summary, the results of this study accentuate the possible effect of socioeconomic factors, health-related characteristics and menstrual history on the incidence of breast cancer in postmenopausal women in the Makkah region. Education programs should be applied to increase breast cancer awareness and possibly decrease its incidence.

Exercise on quality of life and cancer-related fatigue for lymphoma survivors: a systematic review and meta-analysis

BACKGROUND

People treated for lymphoma can experience several significant long-term and late effects, including fatigue and decreased quality of life. This study aimed to systematically review the evidence from randomized controlled trials (RCTs) and to conduct a meta-analysis of the effect of exercise on quality of life and other health outcomes for adults suffering from lymphoma.

METHODS

We searched the following databases and sources: PubMed, Cochrane Library, Embase, Web of Science, and MEDLINE. Such studies would be included if they were RCT designs which focus on observing the evaluated health outcomes of exercise intervention for lymphoma patients or survivors, comparing with non-exercise or wait-list control groups. Two review authors independently screened search results, extracted data, and assessed the quality of trials. We used standardized mean differences for quality of life (QoL), fatigue, sleep quality, and depression.

RESULTS

Six publications have met the inclusion criteria and the exercise interventions are short term. Slight improvement can be seen on QoL, fatigue, sleep quality, and depression due to exercise for lymphoma patients. Subgroup analysis was carried out according to the classification of mind-body exercise and aerobic exercise, and significant progress can be seen after mind-body exercise intervention in the area of fatigue and sleep.

CONCLUSIONS

Short-term exercises do not appear to convey benefits to quality of life and other psychosocial outcomes. Subgroup analysis showed that physical activity together with mental exercise may be more beneficial to lymphoma patients, but it needs more research to verify this finding. The interpretation of this result should be cautious due to the baseline difference, completion efficiency of intervention process, and high heterogeneity.

The effects of physical activity on cancer prevention, treatment and prognosis: A review of the literature

INTRODUCTION

The World Health Organization has reported that approximately 35% of cancer-related deaths are attributed to modifiable risk factors. Among the most important risk factors amenable to modification are obesity and lack of physical activity. The purpose of this article is to review the current evidence of the benefits of physical activity in various types of cancer.

METHODS

A PubMed search for the key words "physical activity and cancer" as well as "exercise and cancer" was used to identify all indexed publications on this topic for potential utilization in this review. One MET was defined as the amount of oxygen consumed while a person is sitting quietly and is about 3.5 mL O2/kg body weight/min. MET represents the ratio of the working metabolic rate to the resting metabolic rate.

RESULTS

Routine physical activity was found to be associated with a reduced incidence of several of the most common malignancies, including colon, breast, lung, and endometrial cancer as well as many others. Physical activity also appears to reduce all-cause mortality and cancer-related mortality among patients with breast and colon cancer, and may improve the functional status and quality of life for these patients during cancer therapy.

CONCLUSIONS

The benefits of physical activity in the prevention and progression of cancer patients are multiple. However, the strength of the available evidence is limited by the observational nature of most studies. Given the probable improvement in prevention, mortality, and quality of life with structured physical activity in different malignancies, it is important that healthcare providers discuss physical activity programs with their cancer patients. Larger randomized trials are recommended.

Determinants of Mammographic Density Change

Background

Mammographic density (MD) is a strong risk factor for breast cancer. We examined how breast cancer risk factors are associated with MD area (cm²) change across age.

Methods

We conducted a cohort study of 31 782 Swedish women ages 40–70 years at time of baseline mammogram. Lifestyle and reproductive risk factors were assessed by a web-based questionnaire. MD was measured as dense area using the STRATUS method (mean over the left and right breast). Linear regression analyses with adjustments for age, body mass index (BMI), and menopausal status at baseline were performed to assess the association between breast cancer risk factors and mean baseline MD. To investigate mean MD change across age, linear regression analyses with adjustments for age, BMI, menopausal status, and age at last mammogram were performed. All tests of statistical significance were two-sided.

Results

Except for oral contraceptive use, established lifestyle and reproductive risk factors for breast cancer were associated with baseline mean MD. The overall average annual MD change was −1.0 cm². BMI and physical activity were statistically significantly associated with MD change. Lean women (BMI <20 kg/m²) had a mean MD change of −1.13 cm² per year (95% confidence interval = −1.25 to −1.02) compared with −0.46 cm² per year (95% confidence interval = −0.57 to −0.35) for women with BMI 30 or higher. The annual MD change was −0.4 cm² larger in women who were very physically active compared with less physically active women.

Conclusions

Our results indicate that all risk factors for breast cancer, except oral contraceptive use, are associated with baseline MD but that only age, BMI, and physical activity are determinants of MD change.

New Insights into the Role of Exercise in Inhibiting mTOR Signaling in Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) does not express estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2 and is characterized by its aggressive nature, lack of targets for targeted therapies, and early peak of recurrence. Due to these specific characteristics, chemotherapy does not usually yield substantial improvements and new target therapies and alternative strategies are needed. The beneficial responses of TNBC survivors to regular exercise, including a reduction in the rate of tumor growth, are becoming increasingly apparent. Physiological adaptations to exercise occur in skeletal muscle but have an impact on the entire body through systemic control of energy homeostasis and metabolism, which in turn influence the TNBC tumor microenvironment. Gaining insights into the causal mechanisms of the therapeutic cancer control properties of regular exercise is important to improve the prescription and implementation of exercise and training in TNBC survivors. Here, we provide new evidence of the effects of exercise on TNBC prevention, control, and outcomes, based on the inhibition of the phosphatidylinositol-3-kinase (PI3K)/protein kinase B (PKB also known as Akt)/mammalian target of rapamycin (mTOR) (PI3K-Akt-mTOR) signaling. These findings have wide-ranging clinical implications for cancer treatment, including recurrence and case management.

Regular physical activity and mammographic density: a cohort study

Purpose

Physical activity is a modifiable lifestyle risk factor in prevention of breast cancer. Mammographic density (MD) is a strong risk factor for breast cancer. We investigate the association of regular physical activity with MD.

Methods

For 5,703 women who participated in the Danish Diet, Cancer and Health cohort (1993–1997) and attended mammographic screening in Copenhagen (1993–2001), MD was assessed at the first screening after cohort entry. MD was defined as a binary measure equivalent to Breast Imaging Report and Data System (BI-RADS) to either mixed/dense or fatty. Participation and duration in physical activities (hours/week) and confounders were assessed by questionnaire at cohort baseline. Logistic regression was used to estimate associations [odds ratios (OR), 95% confidence intervals (CI)] between physical activities and MD.

Results

56.3% of women had mixed/dense MD and 47.6% participated in sports. We found a significant positive association between participation in sports (OR 1.15; 95% CI 1.03–1.28) and do-it-yourself work (1.17; 1.05–1.31) and odds of having mixed/dense MD, which attenuated (1.08; 0.96–1.22 and 1.11; 0.98–1.25, respectively) in a fully adjusted model. No associations were found for time spent on physical activities or total metabolic equivalent of task scores with MD, in fully adjusted models. There was no effect modification of association between any physical activities and MD by obesity (BMI ≥ 30 kg/m²) and menopause status.

Conclusions

Physical activity is not a determinant of MD.

Electronic supplementary material

The online version of this article (10.1007/s10552-018-1075-3) contains supplementary material, which is available to authorized users.

Effect of exercise and/or reduced calorie dietary interventions on breast cancer-related endogenous sex hormones in healthy postmenopausal women

Background

Physical inactivity and being overweight are modifiable lifestyle risk factors that consistently have been associated with a higher risk of postmenopausal breast cancer in observational studies. One biologic hypothesis underlying this relationship may be via endogenous sex hormone levels. It is unclear if changes in dietary intake, physical activity, or both, are most effective in changing these hormone levels.

Objective

This systematic review and meta-analysis examines the effect of reduced caloric dietary intake and/or increased exercise levels on breast cancer-related endogenous sex hormones.

Methods

We conducted a systematic literature search in MEDLINE, Embase, and Cochrane’s Central Register of Controlled Trials (CENTRAL) up to March 2017. Main outcome measures were breast cancer-related endogenous sex hormones.

Randomized controlled trials (RCTs) reporting effects of reduced caloric intake and/or exercise interventions on endogenous sex hormones in healthy, physically inactive postmenopausal women were included. Studies including women using hormone therapy were excluded. The methodological quality of each study was assessed by the Cochrane’s risk of bias tool.

Results

From the 2599 articles retrieved, seven articles from six RCTs were included in this meta-analysis. These trials investigated 1588 healthy postmenopausal women with a mean age ranging from 58 to 61 years. A combined intervention of reduced caloric intake and exercise, with durations ranging from 16 to 52 weeks, compared with a control group (without an intervention to achieve weight loss) resulted in the largest beneficial effects on estrone treatment effect ratio (TER) = 0.90 (95% confidence interval (CI) = 0.83–0.97), total estradiol TER = 0.82 (0.75–0.90), free estradiol TER = 0.73 (0.66–0.81), free testosterone TER = 0.86 (0.79–0.93), and sex hormone biding globulin (SHBG) TER = 1.23 (1.15–1.31). A reduced caloric intake without an exercise intervention resulted in significant effects compared with control on total estradiol TER = 0.86 (0.77–0.95), free estradiol TER = 0.77 (0.69–0.84), free testosterone TER = 0.91 (0.84–0.98), and SHBG TER = 1.20 (1.06–1.36). Exercise without dietary change, versus control, resulted in borderline significant effects on androstenedione TER = 0.97 (0.94–1.00), total estradiol TER = 0. 97 (0.94–1.00), and free testosterone TER = 0. 0.97 (0.95–1.00).

Conclusions and relevance

This meta-analysis of six RCTs demonstrated that there are beneficial effects of exercise, reduced caloric dietary intake or, preferably, a combination of exercise and diet on breast cancer-related endogenous sex hormones in physically inactive postmenopausal women.

Electronic supplementary material

The online version of this article (10.1186/s13058-018-1009-8) contains supplementary material, which is available to authorized users.

Number of Risky Lifestyle Behaviors and Breast Cancer Risk

Background

Lifestyle factors are associated with overall breast cancer risk, but less is known about their associations, alone or jointly, with risk of specific breast cancer subtypes.

Methods

We conducted a case-control subjects study nested within a cohort of women who participated in the Norwegian Breast Cancer Screening Program during 2006-2014 to examine associations between risky lifestyle factors and breast cancer risk. In all, 4402 breast cancer cases subjects with information on risk factors and hormone receptor status were identified. Conditional logistic regression was used to estimate odds ratios (ORs), with 95% confidence intervals (CIs), in relation to five risky lifestyle factors: body mass index (BMI) of 25 kg/m² or greater, three or more glasses of alcoholic beverages per week, ever smoking, fewer than four hours of physical activity per week, and ever use of menopausal hormone therapy. Analyses were adjusted for education, age at menarche, number of pregnancies, and menopausal status. All statistical tests were two-sided.

Results

Compared with women with no risky lifestyle behaviors, those with five had 85% (OR = 1.85, 95% CI = 1.42 to 2.42, P _trend < .0001) increased risk of breast cancer overall. This association was limited to luminal A-like (OR = 2.20, 95% CI = 1.55 to 3.12, P _trend < .0001) and luminal B-like human epidermal growth factor receptor 2 (HER2)-positive (OR = 1.66, 95% CI = 0.61 to 4.54, P _trend < .004) subtypes. Number of risky lifestyle factors was not associated with increased risk of luminal B-like HER2-negative, HER2-positive, or triple-negative subtypes (P _trend > .18 for all).

Conclusions

Number of risky lifestyle factors was positively associated with increased risk for luminal A-like and luminal B-like HER2-positive breast cancer.

Modifiable Lifestyle Factors: Opportunities for (Hereditary) Breast Cancer Prevention - a Narrative Review

Increasing rates of obesity, lack of physical activity, sedentary behavior, and frequent alcohol consumption are major lifestyle-related risk factors for breast cancer. In fact, it has been estimated that about one-third of breast cancer cases are attributable to factors women can change. Most research has focused on examining the impact of one single exposure on breast cancer risk while adjusting for other risk modifiers. Capitalizing on big data, major efforts have been made to evaluate the combined impact of well-established lifestyle factors on overall breast cancer risk. At the individual level, data indicate that even simple behavior modifications could have a considerable impact on breast cancer prevention. Moreover, there is emerging new evidence that adopting a healthy lifestyle may be particularly relevant for women with hereditary susceptibility to breast cancer. On the absolute risk scale, studies suggest that the presence of certain risk factors, such as excessive body weight, had a substantially higher impact on breast cancer risk if women had a hereditary predisposition to cancer. The existing body of knowledge gives the medical professionals guidance as to which factors to focus on when counseling patients. However, well-designed randomized controlled trials utilizing objective methods are crucial to providing concrete recommendations.

Pilot Trial of a Home-based Physical Activity Program for African American Women

PURPOSE

This study aimed to assess the feasibility of a Home-based, Individually-tailored Physical activity Print (HIPP) intervention for African American women in the Deep South.

METHODS

A pilot randomized trial of the HIPP intervention (N = 43) versus wellness contact control (N = 41) was conducted. Recruitment, retention, and adherence were examined, along with physical activity (7-d physical activity recalls, accelerometers) and related psychosocial variables at baseline and 6 months.

RESULTS

The sample included 84 overweight/obese African American women 50-69 yr old in Birmingham, AL. Retention was high at 6 months (90%). Most participants reported being satisfied with the HIPP program and finding it helpful (91.67%). There were no significant between-group differences in physical activity (P = 0.22); however, HIPP participants reported larger increases (mean of +73.9 min·wk (SD 90.9)) in moderate-intensity or greater physical activity from baseline to 6 months compared with the control group (+41.5 min·wk (64.4)). The HIPP group also reported significantly greater improvements in physical activity goal setting (P = 0.02) and enjoyment (P = 0.04) from baseline to 6 months compared with the control group. There were no other significant between-group differences (6-min walk test, weight, physical activity planning, behavioral processes, stage of change); however, trends in the data for cognitive processes, self-efficacy, outcome expectations, and family support for physical activity indicated small improvements for HIPP participants (P > 0.05) and declines for control participants. Significant decreases in decisional balance (P = 0.01) and friend support (P = 0.03) from baseline to 6 months were observed in the control arm and not the intervention arm.

CONCLUSIONS

The HIPP intervention has great potential as a low-cost, high-reach method for reducing physical activity-related health disparities. The lack of improvement in some domains may indicate that additional resources are needed to help this target population reach national guidelines.

The Impact of Exercise Training on Breast Cancer

BACKGROUND/AIM

Physical exercise is increasingly considered by many authors to be a factor reducing the risk of cancer development and premature cancer-related death. Data indicate higher cure rates and longer times of survival in cancer patients who regularly exercise.

MATERIALS AND METHODS

A total of 50 female Sprague-Dawley rats were used in the experiment. Animals at 1 month of age were intraperitoneally injected with N-methyl-N-nitrosourea. Three months following drug administration, rats underwent supervised physical training. The animals were divided into four groups: control untrained group and 3 groups trained with different intensities - i.e. low, moderate and high. Routine histopathological examination of tumors was performed and mitotic activity was assessed by immunohistochemical expression of the Ki-67 antigen.

RESULTS

Ki-67 antigen expression was observed in all analyzed tumors. The increase in Ki-67 antigen expression correlated positively with the increase in training intensity.

CONCLUSION

It can be assumed that low-intensity physical training is safe for patients with breast cancer. However, moderate- and high-intensity training may induce tumor cell proliferation worsening patients' prognosis.

Physical activity during adolescence and young adulthood and the risk of breast cancer in BRCA1 and BRCA2 mutation carriers

BACKGROUND

Physical activity is inversely associated with the risk of breast cancer among women in the general population. It is not clear whether or not physical activity is associated with the risk of BRCA-associated breast cancer.

METHODS

We conducted a case-control study of 443 matched pairs of BRCA mutation carriers to evaluate the association between physical activity and breast cancer risk. Moderate and vigorous physical activities at ages 12-13, ages 14-17, ages 18-22, ages 23-29 and ages 30-34 were determined using the Nurses' Health Study II Physical Activity Questionnaire. We estimated mean metabolic equivalent task hours/week for moderate, vigorous and total physical activities overall (ages 12-34), during adolescence (ages 12-17) and during early adulthood (ages 18-34). Logistic regression analysis was used to estimate the odds ratios (OR) and 95% confidence intervals (CI) for total, moderate and strenuous recreational physical activities and breast cancer risk, by menopausal status.

RESULTS

Overall, there was no significant association between total physical activity and subsequent breast cancer risk (OR_{Q4 vs. Q1} = 1.01, 95% CI 0.69-1.47; P-trend = 0.72). Moderate physical activity between ages 12-17 was associated with a 38% decreased risk of premenopausal breast cancer (OR_{Q4 vs. Q1} = 0.62; 95% CI 0.40-0.96; P-trend = 0.01). We found no association between exercise and breast cancer diagnosed after menopause.

CONCLUSIONS

These findings suggest that early-life physical activity is associated with a reduced risk of premenopausal breast cancer among BRCA mutation carriers.

IMPACT

Future prospective analyses, complemented by mechanistic evidence, are warranted in this high-risk population.

Effects of physical activity on colorectal cancer risk among family history and body mass index subgroups: a systematic review and meta-analysis

Background

Physical activity is consistently associated with a reduced risk of colorectal cancer in epidemiologic studies. This association among higher risk subgroups, such as those with a first-degree family history of colorectal cancer or high body mass index remains unclear.

Methods

We searched MEDLINE for studies examining physical activity and colorectal cancer risk among higher risk subgroups through July 11, 2017. Fifteen and three studies were eligible for inclusion for body mass index and first-degree family history of colorectal cancer subgroups, respectively. Estimates of the highest to lowest comparison of physical activity for each subgroup of risk were pooled using random-effects models.

Results

The pooled associations of physical activity and colorectal cancer risk for those without and with a first-degree family history of colorectal cancer were 0.56 (95% confidence interval (CI) = 0.39–0.80) and 0.72 (95% CI = 0.39–1.32), respectively (p_{heterogeneity} = 0.586). The pooled associations of physical activity and colorectal cancer risk for the low and high body mass index groups were 0.74 (95% CI = 0.66–0.83) and 0.65 (95% CI = 0.53–0.79), respectively (p_{heterogeneity} = 0.389).

Conclusions

Overall, a stronger relative risk of physical activity on colorectal cancer risk was observed in the higher body mass index group, although the difference was not statistically significant, suggesting an added benefit of physical activity as a cancer prevention strategy in population groups with strong risk factors for colorectal cancer. Additional research among these subgroups is warranted.

Electronic supplementary material

The online version of this article (10.1186/s12885-017-3970-5) contains supplementary material, which is available to authorized users.

Alcohol, Physical Activity, Smoking, and Breast Cancer Subtypes in a Large, Nested Case-Control Study from the Norwegian Breast Cancer Screening Program

Background: To what extent alcohol, smoking, and physical activity are associated with the various subtypes of breast cancer is not clear. We took advantage of a large population-based screening cohort to determine whether these risk factors also increase the risk of the poor prognosis subtypes.Methods: We conducted a matched case-control study nested within the Norwegian Breast Cancer Screening Program during 2006-2014. A total of 4,402 breast cancer cases with risk factor and receptor data were identified. Five controls were matched to each case on year of birth and year of screening. Conditional logistic regression was used to estimate ORs of breast cancer subtypes adjusted for potential confounders.Results: There were 2,761 luminal A-like, 709 luminal B-like HER2-negative, 367 luminal B-like HER2-positive, 204 HER2-positive, and 361 triple-negative cancers. Current alcohol consumption was associated with breast cancer risk overall [OR 1.26; 95% confidence interval (CI), 1.09-1.45] comparing 6+ glasses a week to never drinkers. However, this risk increase was found only for luminal A-like breast cancer. Smoking 20+ cigarettes a day was associated with an OR of 1.41 (95% CI, 1.06-1.89) overall, with significant trends for luminal A-like and luminal B-like HER2-negative cancer. Current physical activity (4+ hours/week compared with none) was associated with 15% decreased risk of luminal A-like cancer, but not clearly with other subtypes.Conclusions: In this large study, alcohol, smoking, and physical activity were predominantly associated with luminal A-like breast cancer.Impact: Alcohol, smoking, and physical activity were associated with luminal A-like breast cancer subtype. Cancer Epidemiol Biomarkers Prev; 26(12); 1736-44. ©2017 AACR.