Pathophysiology of exercise intolerance in breast cancer survivors with preserved left ventricular ejection fraction

Relationship between incident cardiovascular disease and quality of life after a breast cancer diagnosis

PURPOSE

Breast cancer survivors are at risk for both poor quality of life (QoL) and cardiovascular disease (CVD). This study examines whether incident CVD after breast cancer independently predicts QoL.

METHODS

Using data from the Women's Health Initiative, we included women who were diagnosed with invasive breast cancer during follow-up and free of prevalent CVD prior to breast cancer. CVD was defined as adjudicated coronary heart disease, heart failure, or stroke. Physical and mental QoL, measured by the SF-36 Physical and Mental Component Scores (PCS and MCS, respectively), were recorded after breast cancer. Poor PCS and MCS were defined as scores < 40. We used adjusted time-dependent Cox proportional hazards models, accounting for time to CVD.

RESULTS

Among 2912 BC survivors (mean age at BC diagnosis = 67), 1094 (37.6%) and 313 (10.7%) women had a post-breast cancer PCS and MCS score < 40, respectively, at a median of 2.5 years. A higher proportion of women had poor PCS scores post-BC (37.5% vs. 19.2%, P < 0.001) but not MCS (10.4% vs. 8.2%, P = 0.10). After adjustment for key covariates, incident CVD was associated with a 1.95-fold (95% CI 1.42, 2.67) greater risk of poor PCS scores (P < 0.001), but was not associated with poor MCS (HR 1.23, 95% CI 0.57, 2.65, P = 0.59)).

CONCLUSIONS

Incident CVD after breast cancer was associated with poor physical QoL but not mental QoL.

IMPLICATIONS FOR CANCER SURVIVORS

This study highlights the importance of regular assessments of QoL and need for strategies to improve physical QoL in breast cancer survivors with CVD.

Cardio-Oncology and Heart Failure: a Scientific Statement From the Heart Failure Society of America

Heart failure and cancer remain 2 of the leading causes of morbidity and mortality, and the 2 disease entities are linked in a complex manner. Patients with cancer are at increased risk of cardiovascular complications related to the cancer therapies. The presence of cardiomyopathy or heart failure in a patient with new cancer diagnosis portends a high risk for adverse oncology and cardiovascular outcomes. With the rapid growth of cancer therapies, many of which interfere with cardiovascular homeostasis, heart failure practitioners need to be familiar with prevention, risk stratification, diagnosis, and management strategies in cardio-oncology. This Heart Failure Society of America statement addresses the complexities of heart failure care among patients with active cancer diagnoses and cancer survivors. Risk stratification, monitoring and management of cardiotoxicity are presented across stages A through D heart failure, with focused discussion on heart failure with preserved ejection fraction and special populations, such as survivors of childhood and young-adulthood cancers. We provide an overview of the shared risk factors between cancer and heart failure, highlighting heart failure as a form of cardiotoxicity associated with many different cancer therapeutics. Finally, we discuss disparities in the care of patients with cancer and cardiac disease and present a framework for a multidisciplinary-team approach and critical collaboration among heart failure, oncology, palliative care, pharmacy, and nursing teams in the management of these complex patients.

Clinical, Analytical, and Echocardiographic Associations of Impaired Cardiorespiratory Fitness After Anthracycline Chemotherapy in Breast Cancer: EPIC Fitness Study

PURPOSE

This study explores the effects of anthracycline chemotherapy (AC) on breast cancer patients, focusing on changes in body composition, advanced echocardiographic parameters at rest and during exercise, and biomarkers; and subsequently assesses whether these parameters are associated with impaired cardiorespiratory fitness (CRF).

METHODS

In this prospective study, we evaluated women with early-stage breast cancer undergoing AC at three visits: before AC, 1 month after, and 6 months post-AC.

RESULTS

The study included 32 women with breast cancer, with functional disability increasing from 9.0% pre-AC to 43.8% at 1 month and 53.1% at 6 months post-AC. At 1 month, patients with functional disability exhibited higher rates of cancer therapy-related cardiac dysfunction (CTRCD) (85.7% vs. 55.5%) and, during exercise, showed lower left ventricular ejection fraction (LVEF), reduced contractile reserve and stroke volume (SV); along with elevated IL-6, PlGF, and MPO levels. By 6 months, these patients maintained higher CTRCD rates (35.3% vs. 0%), lower SV and cardiac output (CO), reduced global longitudinal strain (GLS), and decreased global work index (GWI). During exercise, they had lower SV; additionally, they exhibited higher MPO levels and increased body and visceral fat. In our multivariable model: age, body fat, resting GWI, exercise LVEF, and CO were independently associated with VO2peak.

CONCLUSION

Significant and persistent CRF reductions are common in breast cancer patients post-AC. While resting LVEF and GLS were not linked to VO2peak, resting MWI and exercise LVEF and CO were, potentially identifying patients at increased long-term heart failure risk who would benefit from cardioprotective strategies like cardio-oncology rehabilitation. It is important to recognize that impaired CRF is multifactorial, as demonstrated by age and body fat being independently associated with VO2peak, and the impact of non-cardiac factors should be better studied. Our findings highlight the need for further research on CTRCD definition, suggesting that CPET and advanced exercise echocardiography could enhance risk stratification.

Cardiopulmonary Exercise Testing Characterizes Silent Cardiovascular Abnormalities in Asymptomatic Pediatric Cancer Survivors

Late-onset cardiovascular complications are serious concerns for pediatric cancer survivors (PCS) including those who are asymptomatic. We investigated whether cardiopulmonary exercise testing (CPET) can delineate the underlying pathophysiology of preclinical cardiovascular abnormalities in PCS. We examined CPET data via cycle ergometer in asymptomatic PCS with normal echocardiogram and age-matched controls. Peak and submaximal parameters were analyzed. Fifty-three PCS and 60 controls were studied. Peak oxygen consumption (VO₂), peak work rate (WR), and ventilatory anaerobic threshold (VAT) were significantly lower in PCS than controls (1.86 ± 0.53 vs. 2.23 ± 0.61 L/min, 125 ± 45 vs. 154 ± 46 W, and 1.20 ± 0.35 vs. 1.42 ± 0.43 L/min, respectively; all p < 0.01), whereas peak heart rate (HR) and ventilatory efficiency (a slope of minute ventilation over CO₂ production or ∆VE/∆VCO₂) were comparable. Peak respiratory exchange ratio (RER) was significantly higher in PCS (p = 0.0006). Stroke volume (SV) reserve was decreased in PCS, indicated by simultaneous higher dependency on HR (higher ∆HR/∆WR) and lower peak oxygen pulse (OP). Twelve PCS with high peak RER (≥ 1.3) revealed lower pVO₂ and VAT than the rest of PCS despite higher ventilatory efficiency (lower ∆VE/∆VCO₂), suggesting fundamental deficiency in oxygen utilization in some PCS. Poor exercise performance in PCS may be mainly attributed to limited stroke volume reserve, but the underlying pathophysiology is multifactorial. Combined assessment of peak and submaximal CPET parameters provided critical information in delineating underlying exercise physiology of PCS.

Inflammatory, Oxidative Stress, and Cardiac Damage Biomarkers and Radiation-Induced Fatigue in Breast Cancer Survivors

PURPOSE

Studies examining biomarkers associated with fatigue in breast cancer survivors treated with radiation are limited. Therefore, we examined the longitudinal association between serum biomarkers and post-breast cancer fatigue in survivors treated with radiation: [oxidative stress] 8-hydroxyguanosine, myeloperoxidase; [inflammation] interleukin-6 (IL-6), c-reactive protein, growth differentiation factor-15 (GDF-15), placental growth factor, transforming growth factor-beta, [cardiac damage] cystatin-C, troponin-I.

METHODS

In a secondary analysis, we included participants from the Women's Health Initiative if they had: a previous breast cancer diagnosis (stages I-III), no prior cardiovascular diseases, pre-and post-breast cancer serum samples drawn approximately 3 years apart, and fatigue measured using the Short-Form 36 vitality subscale at both serum collections. Biomarkers were measured using ELISA or RT-qPCR and modeled as the log2 post-to pre-breast cancer ratio.

RESULTS

Overall, 180 women with a mean (SD) age of 67.0 (5.5) years were included. The mean (SD) vitality scores were 66.2 (17.2) and 59.7 (19.7) pre- and post-breast cancer, respectively. Using multivariable weighted linear regression, higher biomarker ratios of cystatin-C, IL-6, and GDF-15 were associated with a lower vitality score (i.e., higher fatigue). For example, for each 2-fold difference in cystatin-C biomarker ratio, the vitality score was lower by 7.31 points (95% CI: -14.2, -0.45).

CONCLUSION

Inflammatory and cardiac damage biomarkers are associated with fatigue in breast cancer survivors treated with radiation; however, these findings should be replicated in a larger sample. Biomarkers could be measured in clinical practice or assessed in risk prediction models to help identify patients at high risk for fatigue.

Cardiotoxicity is mitigated after a supervised exercise program in HER2-positive breast cancer undergoing adjuvant trastuzumab

Background

Trastuzumab is used, alone or in conjunction with standard chemotherapy, to treat HER2-positive breast cancer (BC). Although it improves cancer outcomes, trastuzumab. can lead to cardiotoxicity. Physical exercise is a safe and effective supportive therapy in the management of side effects, but the cardioprotective effects of exercise are still unclear.

Objectives

The primary aim of this study was to test whether trastuzumab-induced cardiotoxicity [left ventricular ejection fraction (LVEF) under 50%, or an absolute drop in LVEF of 10%] was reduced after a supervised exercise program of 3 months in patients with HER2-positive breast cancer. Secondary endpoints were to evaluate (i) cardiotoxicity rates using other criteria, (ii) cardiac parameters, (iii) cardiorespiratory fitness and (iv) whether a change in LVEF influences the cardiorespiratory fitness.

Methods

89 women were randomized to receive adjuvant trastuzumab in combination with a training program (training group: TG; n = 46) or trastuzumab alone (control group: CG; n = 43). The primary and secondary endpoints were evaluated at the end of the supervised exercise program of 3 months (T3).

Results

After exercise program, 90.5 % of TG patients and 81.8% of CG patients did not exhibit cardiotoxicity. Furthermore, whatever the used criterion, percentage of patients without cardiotoxicity were greater in TG (97.6 and 100% respectively) than in CG (90.9 and 93.9% respectively). LVEF and GLS values remained stable in both groups without any difference between the groups. In contrast, at T3, peak VO2 (+2.6 mL.min−1.kg−1; 95%CI, 1.8 to 3.4) and maximal power (+21.3 W; 95%CI, 17.3 to 25.3) increased significantly in TG, whereas they were unchanged in CG (peak VO2: +0.2 mL.min−1.kg−1; 95%CI, −0.5 to 0.9 and maximal power: +0.7 W, 95%CI, −3.6 to 5.1) compared to values measured at T0. No correlation between LVEF changes and peak VO2 or maximal power was observed.

Conclusion

A 12-week supervised exercise regimen was safe and improved the cardiopulmonary fitness in particular peak VO2, in HER2-positive BC patients treated with adjuvant trastuzumab therapy. The study is under powered to come to any conclusion regarding the effect on cardiotoxicity.

Clinical trial registration

www.ClinicalTrials.gov, identifier: NCT02433067.

Cancer treatment-related cardiac dysfunction in breast cancer survivors: A retrospective descriptive study using electronic health records from a Korean tertiary hospital

PURPOSE

The population overlap of breast cancer and cardiovascular diseases (CVDs) has increased due to early breast cancer detection and treatment and aging population trends. Moreover, breast cancer patients are at an increased risk for CVDs consequent to cancer treatments. We aimed to understand the characteristics of breast cancer patients with pre-existing CVDs and of those diagnosed with CVDs after receiving chemotherapy, and cancer treatment-related cardiac dysfunction's occurrence among Korean breast cancer patients with CVDs.

METHODS

This retrospective descriptive study, which collected clinical data from electronic health records from a Korean tertiary hospital, included 1200 female breast cancer patients with CVDs, aged 15-75 years.

RESULTS

A total of 45.7% had pre-existing CVDs, and 91.6% were classified as very high-risk for cardiotoxicity in the pre-existing CVDs group. Among the 1200 breast cancer patients with CVDs, only 439 patients had left ventricular ejection fraction (LVEF) data during their cancer treatment, and 121 received baseline assessment for LVEF. Of the 439 patients with LVEF data, 134 patients have been classified into cancer treatment-related cardiac dysfunction (CTRCD), and the median period from cancer diagnosis to CTRCD occurrence was 26.5 months.

CONCLUSION

Despite the high cardiotoxicity risk of breast cancer patients with pre-existing CVDs, baseline studies of the risk assessment before chemotherapy were insufficient to support the prevention and early detection of cardiotoxicity. Therefore, it is paramount to consider how nurses focus on risk stratification before chemotherapy and support the regular monitoring of breast cancer survivors' cardiac functioning, to maintain optimal health status.

Lifestyle and Cardiovascular Risk Factors Associated With Heart Failure Subtypes in Postmenopausal Breast Cancer Survivors

Background

Breast cancer (BC) survivors experience an increased burden of long-term comorbidities, including heart failure (HF). However, there is limited understanding of the risk for the development of HF subtypes, such as HF with preserved ejection fraction (HFpEF), in BC survivors.

Objectives

This study sought to estimate the incidence of HFpEF and HF with reduced ejection fraction (HFrEF) in postmenopausal BC survivors and to identify lifestyle and cardiovascular risk factors associated with HF subtypes.

Methods

Within the Women’s Health Initiative, participants with an adjudicated diagnosis of invasive BC were followed to determine the incidence of hospitalized HF, for which adjudication procedures determined left ventricular ejection fraction. We calculated cumulative incidences of HF, HFpEF, and HFrEF. We estimated HRs for risk factors in relation to HF, HFpEF, and HFrEF using Cox proportional hazards survival models.

Results

In 2,272 BC survivors (28.6% Black and 64.9% White), the cumulative incidences of hospitalized HFpEF and HFrEF were 6.68% and 3.96%, respectively, over a median of 7.2 years (IQR: 3.6-12.3 years). For HFpEF, prior myocardial infarction (HR: 2.83; 95% CI: 1.28-6.28), greater waist circumference (HR: 1.99; 95% CI: 1.14-3.49), and smoking history (HR: 1.65; 95% CI: 1.01-2.67) were the strongest risk factors in multivariable models. With the exception of waist circumference, similar patterns were observed for HFrEF, although none were significant. In relation to those without HF, the risk of overall mortality in BC survivors with hospitalized HFpEF was 5.65 (95% CI: 4.11-7.76), and in those with hospitalized HFrEF, it was 3.77 (95% CI: 2.51-5.66).

Conclusions

In this population of older, racially diverse BC survivors, the incidence of HFpEF, as defined by HF hospitalizations, was higher than HFrEF. HF was also associated with an increased mortality risk. Risk factors for HF were largely similar to the general population with the exception of prior myocardial infarction for HFpEF. Notably, both waist circumference and smoking represent potentially modifiable factors.

Can the Six-Minute Walk Test Be Used to Individualize Physical Activity Intensity in Patients with Breast Cancer?

Simple Summary

Physical activity has proven to be effective in breast cancer patients. Appropriate exercise intensity for each patient is necessary to maintain this practice in patients with possible comorbidities and potential adverse events of specific treatments. These programs should be proposed to many patients so to prescribe the adapted program; this will necessitate easy and cost-effective tests. It is useful to use an adapted target heart rate (HR) to prescribe exercise intensity. In this work, we assessed the potential equivalence of the ventilatory threshold HR obtained during a cardiopulmonary exercise test and the HR measured over the last 3 min of the six-minute walk test (6MWT-HR). At baseline, the 6MWT-HR was in good agreement and showed moderate but statistical correlation with the VT-HR in breast cancer patients. The best correlation between these two tests was obtained after the APA program and chemotherapy. These results were independent of body mass index. The 6MWT is useful to prescribe APA programs before and also after chemotherapy concomitant with physical activity.

Abstract

Background: Adapted physical activity (APA) aids breast cancer patients. It is necessary to use an adapted target heart rate (HR) when prescribing exercise intensity. Methods: In total, 138 patients previously included in two published randomized clinical trials underwent the CPET and 6MWT before and after adjuvant therapy. Of these patients, 85 had performed APA, and 53 had received only the usual therapy. HRs were recorded during the two tests. Results: Before starting chemotherapy, good agreement (intraclass correlation (ICC) 0.69; confidence interval at 95% IC_0.95 (0.591–0.769); p < 0.001) and a moderate correlation were evident between the 6MWT-HR and ventilatory threshold HR of the CPET (r = 0.70; p < 0.001). Good agreement and a high positive correlation were noted only in the group who engaged in APA (ICC 0.77; IC_0.95 (0.659–0.848); p < 0.001; r = 0.8; p < 0.01); moderate agreement and a moderate positive correlation were apparent in the control group (ICC 0.57; IC_0.95 (0.329–0.74); p < 0.001; r = 0.6; p < 0.01). The correlations were independent of age and body mass index. Conclusions: The 6MWT-HR can be used to prescribe exercise intensity for breast cancer patients both before and after specific treatment with concomitant APA.

Rethinking Rehabilitation: A REVIEW OF PATIENT POPULATIONS WHO CAN BENEFIT FROM CARDIAC REHABILITATION

Although cardiac rehabilitation (CR) is safe and highly effective for individuals with various cardiovascular health conditions, to date there are only seven diagnoses or procedures identified by the Centers for Medicare & Medicaid Services that qualify for referral. When considering the growing number of individuals with cardiovascular disease (CVD), or other health conditions that increase the risk for CVD, it is important to determine the extent for which CR could benefit these populations. Furthermore, there are some patients who may currently be eligible for CR (spontaneous coronary artery dissection, left ventricular assistant device) but make up a relatively small proportion of the populations that are regularly attending and participating. Thus, these patient populations and special considerations for exercise might be less familiar to professionals who are supervising their programs. The purpose of this review is to summarize the current literature surrounding exercise testing and programming among four specific patient populations that either do not currently qualify for (chronic and end-stage renal disease, breast cancer survivor) or who are eligible but less commonly seen in CR (sudden coronary artery dissection, left ventricular assist device). While current evidence suggests that individuals with these health conditions can safely participate in and may benefit from supervised exercise programming, there is an immediate need for high-quality, multisite clinical trials to develop more specific exercise recommendations and support the inclusion of these populations in future CR programs.

Traditional markers of cardiac toxicity fail to detect marked reductions in cardiorespiratory fitness among cancer patients undergoing anti-cancer treatment

AIMS

Left ventricular ejection fraction (LVEF) is standard of care for evaluating chemotherapy-associated cardiotoxicity, although global longitudinal strain (GLS) offers advantages. However, neither change in LVEF or GLS has been associated with short-term symptoms, functional capacity, or long-term heart failure (HF) risk. We sought to determine whether an integrative measure of cardiovascular function (VO2peak) that is strongly associated with HF risk would be more sensitive to cardiac damage induced by cancer treatment than LVEF, GLS, or cardiac biomarkers.

METHODS AND RESULTS

Patients (n = 206, 53 ± 13 years, 35% male) scheduled to commence anti-cancer treatment completed assessment prior to, and within 6 months after therapy. Changes in echocardiographic measures of LV function (LVEF, GLS), cardiac biomarkers (troponin and BNP), and cardiorespiratory fitness (VO2peak) were measured. LV function was normal prior to treatment (LVEF 61 ± 5%; GLS -19.4 ± 2.1), but VO2peak was only 88 ± 26% of age-predicted. After treatment, VO2peak was reduced by 7 ± 15% (equivalent of 7 years normal ageing, P < 0.0001) and the rates of functional disability (defined as VO2peak ≤ 18 mL/min/kg) almost doubled (15% vs. 26%, P = 0.016). In contrast, small, reductions in LVEF (59 ± 5% vs. 58 ± 5%, P = 0.03) and GLS (-19.4 ± 2.1 vs. -18.9 ± 2.2, P = 0.002) and an increase in troponin levels (4.0 ± 6.9 vs. 26.4 ± 26.2 ng/mL, P < 0.0001) were observed.

CONCLUSION

Anti-cancer treatment is associated with marked reductions in functional capacity that occur independent of reductions in LVEF and GLS. The assessment of VO2peak prior to, and following treatment may be a more sensitive means of identifying patients at increased risk of HF.

Exercise as a diagnostic and therapeutic tool for preventing cardiovascular morbidity in breast cancer patients- the BReast cancer EXercise InTervention (BREXIT) trial protocol

BACKGROUND

Anthracycline chemotherapy (AC) is an efficacious (neo) adjuvant treatment for early-stage breast cancer (BCa), but is associated with an increased risk of cardiac dysfunction and functional disability. Observations suggest that regular exercise may be a useful therapy for the prevention of cardiovascular morbidity but it is yet to be interrogated in a large randomised trial. The primary aims of this study are to: 1) determine if 12-months of ET commenced at the onset of AC can reduce the proportion of BCa patients with functional disability (peak VO2, < 18 ml/kg/min), and 2) compare current standard-of-care for detecting cardiac dysfunction (resting left-ventricular ejection fraction assessed from 3-dimensional echocardiography) to measures of cardiac reserve (peak exercise cardiac output assessed from exercise cardiac magnetic resonance imaging) for predicting the development of functional disability 12-months following AC. Secondary aims are to assess the effects of ET on VO2peak, left ventricular morphology, vascular stiffness, cardiac biomarkers, body composition, bone mineral density, muscle strength, physical function, habitual physical activity, cognitive function, and multidimensional quality of life.

METHODS

One hundred women with early-stage BCa (40-75 years) scheduled for AC will be randomized to 12-months of structured exercise training (n = 50) or a usual care control group (n = 50). Participants will be assessed at baseline, 4-weeks following completion of AC (4-months) and at 12-months for all measures.

DISCUSSION

Women diagnosed with early-stage BCa have increased cardiac mortality. More sensitive strategies for diagnosing and preventing AC-induced cardiovascular impairment are critical for reducing cardiovascular morbidity and improving long-term health outcomes in BCa survivors.

TRIAL REGISTRATION

Australia & New Zealand Clinical Trials Registry (ANZCTR), ID: 12617001408370 . Registered on 5th of October 2017.

Cardiovascular Consequences of Skeletal Muscle Impairments in Breast Cancer

Breast cancer survivors suffer from disproportionate cardiovascular disease risk compared to age-matched controls. Beyond direct cardiotoxic effects due to treatments such as chemotherapy and radiation, breast-cancer-related reductions in skeletal muscle mass, quality and oxidative capacity may further contribute to cardiovascular disease risk in this population by limiting the ability to engage in aerobic exercise—a known promoter of cardiovascular health. Indeed, 20–30% decreases in peak oxygen consumption are commonly observed in breast cancer survivors, which are indicative of exercise intolerance. Thus, breast-cancer-related skeletal muscle damage may reduce exercise-based opportunities for cardiovascular disease risk reduction. Resistance training is a potential strategy to improve skeletal muscle health in this population, which in turn may enhance the capacity to engage in aerobic exercise and reduce cardiovascular disease risk.

The Utility of Cardiac Reserve for the Early Detection of Cancer Treatment-Related Cardiac Dysfunction: A Comprehensive Overview

With progressive advancements in cancer detection and treatment, cancer-specific survival has improved dramatically over the past decades. Consequently, long-term health outcomes are increasingly defined by comorbidities such as cardiovascular disease. Importantly, a number of well-established and emerging cancer treatments have been associated with varying degrees of cardiovascular injury that may not emerge until years following the completion of cancer treatment. Of particular concern is the development of cancer treatment related cardiac dysfunction (CTRCD) which is associated with an increased risk of heart failure and high risk of morbidity and mortality. Early detection of CTRCD appears critical for preventing long-term cardiovascular morbidity in cancer survivors. However, current clinical standards for the identification of CTRCD rely on assessments of cardiac function in the resting state. This provides incomplete information about the heart's reserve capacity and may reduce the sensitivity for detecting sub-clinical myocardial injury. Advances in non-invasive imaging techniques have enabled cardiac function to be quantified during exercise thereby providing a novel means of identifying early cardiac dysfunction that has proved useful in several cardiovascular pathologies. The purpose of this narrative review is (1) to discuss the different non-invasive imaging techniques that can be used for quantifying different aspects of cardiac reserve; (2) discuss the findings from studies of cancer patients that have measured cardiac reserve as a marker of CTRCD; and (3) highlight the future directions important knowledge gaps that need to be addressed for cardiac reserve to be effectively integrated into routine monitoring for cancer patients exposed to cardiotoxic therapies.

Increased skeletal intermuscular fat is associated with reduced exercise capacity in cancer survivors: a cross-sectional study

BACKGROUND

Cancer survivors experience on average a 20% reduction in peak exercise capacity (VO2 peak) post-cancer treatment. Intermuscular fat (IMF) is a strong predictor of reduced exercise capacity in heart failure (HF) patients; however it is unknown whether increased IMF is related to reduced VO2 peak in cancer survivors.

METHODS AND RESULTS

Twenty eight individuals: 14 cancer survivors > 12-months post-cancer treatment and 14 individuals without cancer were matched on age, gender, and body mass index (BMI). Participants underwent magnetic resonance imaging (MRI) assessments of IMF within the paraspinal muscles, VO2 peak and exercise-associated measures of left ventricular ejection fraction (LVEF). Blinded analyses were performed. Associations between the ratio of IMF to skeletal muscle (SM) were estimated using Pearson's partial correlation coefficients. Individuals with cancer and non-cancer comparators were of similar age (54 ± 17 versus 54 ± 15 years; p = 1.0), gender (5 men and 9 women, both groups), and BMI (27 ± 4 versus 26 ± 4; p = 0.57). Peak VO2 was 22% lower in cancer survivors versus non-cancer comparators (26.9 vs 34.3 ml/kg/min; p = 0.005), and was correlated with IMF:SM in both cancer survivors and non-cancer individuals after accounting for exercise-associated LVEF, resting LVEF, BMI, other body fat depots, and cardiovascular disease (CVD) co-morbidities (p < 0.001 to 0.08 for all adjusted correlations).

CONCLUSION

Among cancer survivors that previously received anthracyclines, increased intermuscular fat is associated with reduced VO2 peak even after accounting for exercise-associated cardiac function. This suggests IMF is important in the development of exercise intolerance, an outcome experienced by a large number of cancer survivors.

Curing breast cancer and killing the heart: A novel model to explain elevated cardiovascular disease and mortality risk among women with early stage breast cancer

Due to advances in prevention, early detection and treatment, early breast cancer mortality has decreased by nearly 40% during the last four decades. Yet, the risk of cardiovascular disease (CVD) mortality is significantly elevated following a breast cancer diagnosis, and it is a leading cause of death in this population. This review will discuss the most recent evidence for risks, pathology, mechanisms, and prevention of CVD morbidity and mortality in women with breast cancer. This evidence will be synthesized into a new model 'the compounding risk and protection model.' This model proposes that the balance between risk factors (i.e., older age, pre-existing traditional CVD risk factors and shared biologic pathways for CVD and cancer such as inflammation, as well as treatment-related and lifestyle toxicity) and potential protection factors (i.e., lifelong non-smoking, regular physical activity, a healthy diet rich in fruits and vegetables, and management of body weight and stress, heart failure therapy) determine the individual risk of CVD morbidity and mortality after diagnosis of early breast cancer.

Determinants of exercise intolerance in breast cancer patients prior to anthracycline chemotherapy

Women with early-stage breast cancer have reduced peak exercise oxygen uptake (peak VO2 ). The purpose of this study was to evaluate peak VO2 and right (RV) and left (LV) ventricular function prior to adjuvant chemotherapy. Twenty-nine early-stage breast cancer patients (mean age: 48 years) and 10 age-matched healthy women were studied. Participants performed an upright cycle exercise test with expired gas analysis to measure peak VO2 . RV and LV volumes and function were measured at rest, submaximal and peak supine cycle exercise using cardiac magnetic resonance imaging. Peak VO2 was significantly lower in breast cancer patients versus controls (1.7 ± 0.4 vs. 2.3 ± 0.5 L/min, P = 0.0013; 25 ± 6 vs. 35 ± 6 mL/kg/min, P = 0.00009). No significant difference was found between groups for peak upright exercise heart rate (174 ± 13 vs. 169 ± 16 bpm, P = 0.39). Rest, submaximal and peak exercise RV and LV end-diastolic and end-systolic volume index, stroke index, and cardiac index were significantly lower in breast cancer patients versus controls (P < 0.05 for all). No significant difference was found between groups for rest and exercise RV and LV ejection fraction. Despite preserved RV and LV ejection fraction, the decreased peak VO2 in early-stage breast cancer patients prior to adjuvant chemotherapy is due in part to decreased peak cardiac index secondary to reductions in RV and LV end-diastolic volumes.

Measurement and correction of the bulk magnetic susceptibility effects of fat: application in venous oxygen saturation imaging

PURPOSE

To develop a correction method for the effects of the magnetic susceptibility of fat (χ_Fat ) on the calculation of venous oxygen saturation (SvO₂ ).

THEORY

The magnetic field shifts associated with the magnetic susceptibility of deoxyhemoglobin can be used to estimate SvO₂ , a measure of oxygen extraction and metabolism. However, the distinct magnetic susceptibility of fat surrounding targeted veins will give rise to magnetic field perturbations that will extend into the vein and surrounding tissues, potentially confounding the calculation of SvO₂ .

METHODS

Multi-echo modified Dixon fat-water separated imaging was used to quantify fat-water distributions around the superficial femoral vein (venous return from the lower leg). Fat fraction images were used to generate χ_Fat images, to calculate and remove the associated fat-susceptibility-induced magnetic field shifts before the estimation of SvO₂ . This approach was evaluated at rest and with plantar flexion exercise to evaluate calf muscle oxygen extraction in 10 healthy subjects.

RESULTS

The presence of fat around the vein resulted in complex magnetic field shifts and errors in estimated SvO₂ . Corrected resting SvO₂ values were significantly larger than those measured with conventional methods, at rest (72.6 ± 11.0% vs. 65.2 ± 12.2%, P < 0.05) and post-exercise (37.4 ± 12.3% vs. 31.7 ± 12.7%, P < 0.05), with larger errors in individuals and/or regions with increased fat volumes. Estimation and removal of the field-effects from χ_Fat enabled the use of fat tissues for the measurement and removal of the background magnetic field.

CONCLUSIONS

The magnetic susceptibility effects of fat can confound SvO₂ estimation, but the susceptibility field effects can estimated and removed with the use of modified Dixon fat-water separated imaging.

Cardiovascular Magnetic Resonance in the Oncology Patient

Patients with or receiving potentially cardiotoxic treatment for cancer are susceptible to developing decrements in left ventricular mass, diastolic function, or systolic function. They may also experience valvular heart disease, pericardial disease, or intracardiac masses. Cardiovascular magnetic resonance may be used to assess cardiac anatomy, structure, and function and to characterize myocardial tissue. This combination of features facilitates the diagnosis and management of disease processes in patients with or those who have survived cancer. This report outlines and describes prior research involving cardiovascular magnetic resonance for assessing cardiovascular disease in patients with or previously having received treatment for cancer.

Meta-analysis of Exercise Training on Vascular Endothelial Function in Cancer Survivors

Cancer and cardiovascular disease (CVD) are leading causes of morbidity and mortality in the United States. Vascular endothelial dysfunction, an important contributor in the development of CVD, improves with exercise training in patients with CVD. However, the role of regular exercise to improve vascular function in cancer survivors remains equivocal. We performed a meta-analysis to determine the effect of exercise training on vascular endothelial function in cancer survivors. We searched PubMed (1975 to 2016), EMBASE CINAHL (1937 to 2016), OVID MEDLINE (1948 to 2016), and Cochrane Central Registry of Controlled Trials (1991 to 2016) using search terms: vascular function, endothelial function, flow-mediated dilation [FMD], reactive hyperemia, exercise, and cancer. Studies selected were randomized controlled trials of exercise training on vascular endothelial function in cancer survivors. We calculated pooled effect sizes and performed a meta-analysis. We identified 4 randomized controlled trials (breast cancer, n=2; prostate cancer, n=2) measuring vascular endothelial function by FMD (n=3) or reactive hyperemia index (n=1), including 163 cancer survivors (exercise training, n=82; control, n=81). Aerobic exercise training improved vascular function (n=4 studies; standardized mean difference [95% CI]=0.65 [0.33, 0.96], I²=0%; FMD, weighted mean difference [WMD]=1.28 [0.22, 2.34], I²=23.2%) and peak exercise oxygen uptake (3 trials; WMD [95% CI]=2.22 [0.83, 3.61] mL/kg/min; I²=0%). Our findings indicate that exercise training improves vascular endothelial function and exercise capacity in breast and prostate cancer survivors.

Lifestyle Interventions to Improve Cardiorespiratory Fitness and Reduce Breast Cancer Recurrence

As patients are living longer after a cancer diagnosis, survivorship is becoming increasingly important in cancer care. The sequelae of multimodality therapies include weight gain and decreased cardiorespiratory fitness, which increase cardiovascular risk. Evidence suggests that physical activity reduces the risk of breast cancer recurrence and death. Avoidance of weight gain after therapy also improves outcomes after a diagnosis of breast cancer. Prospective randomized trials must be performed to determine the benefits of specific physical activity and dietary habits for survivors of breast cancer. This review outlines the important physiologic changes that occur with antineoplastic therapy and the important role of exercise and diet.