Search

The field of cardio-oncology has emerged in response to the increased risk of cardiovascular disease (CVD) in patients with cancer. However, recent studies suggest a more complicated CVD-cancer relationship, wherein development of CVD, either prior to or following a cancer diagnosis, can also lead to increased risk of cancer and worse outcomes for patients. In this review, we describe the current evidence base, across epidemiological as well as preclinical studies, which supports the emerging concept of ‘reverse-cardio oncology’, or CVD-induced acceleration of cancer pathogenesis.

Observational findings suggest exercise is associated with improved outcomes in early-stage breast cancer. However, whether exercise has biological activity in patients with breast cancer has not been investigated. Preoperative window of opportunity studies provide a setting in which to test the short-term effects of novel treatment strategies on validated surrogates. See related article by Ligibel et al., p. 5398

Purpose To evaluate the effects of exercise therapy on cardiorespiratory fitness (CRF) in randomized controlled trials (RCTs) among patients with adult-onset cancer. Secondary objectives were to evaluate treatment effect modifiers, safety, and fidelity. Methods A systematic search of PubMed, Embase, Cumulative Index to Nursing and Allied Health Literature, and the Cochrane Library was conducted to identify RCTs that compared exercise therapy to a nonexercise control group. The primary end point was change in CRF as evaluated by peak oxygen consumption (VO2peak; in mL O2 × kg−1 × min−1) from baseline to postintervention. Subgroup analyses evaluated whether treatment effects differed as a function of exercise prescription (ie, modality, schedule, length, supervision), study characteristics (ie, intervention timing, primary cancer site), and publication year. Safety was defined as report of any adverse event (AE); fidelity was evaluated by rates of attendance, adherence, and loss to follow-up. Results Forty-eight unique RCTs that represented 3,632 patients (mean standard deviation age, 55 ± 7.5 years; 68% women); 1,990 (55%) and 1,642 (45%) allocated to exercise therapy and control/usual care groups, respectively, were evaluated. Exercise therapy was associated with a significant increase in CRF (+2.80 mL O2 × kg−1 × min−1) compared with no change (+0.02 mL O2 × kg−1 × min−1) in the control group (weighted mean differences, +2.13 mL O2 × kg−1 × min−1; 95% CI, 1.58 to 2.67; I2, 20.6; P < .001). No statistical significant differences were observed on the basis of any treatment effect modifiers. Thirty trials (63%) monitored AEs; a total of 44 AEs were reported. The mean standard deviation loss to follow-up, attendance, and adherence rates were 11% ± 13%, 84% ± 12%, and 88% ± 32%, respectively. Conclusion Exercise therapy is an effective adjunctive therapy to improve CRF in patients with cancer. Our findings support the recommendation of exercise therapy for patients with adult-onset cancer.

Advances in detection and supportive care strategies have led to improvements in cancer-specific and overall survival after a diagnosis of early-stage breast cancer. These improvements, however, are associated with an increase in competing forms of morbidity and mortality particularly cardiovascular disease (CVD). Indeed, in certain subpopulations of patients after early breast cancer, CVD is not only the leading cause of mortality but these women also have an increased risk of CVD-specific morbidity, including elevated incidence of coronary artery disease and heart failure (HF) compared to sex- and age-matched counterparts. Exercise treatment is established as the cornerstone of primary and secondary prevention of CVD in multiple clinical populations. The potential benefits of exercise treatment to modulate CVD or CVD risk factors before, immediately after, or in the months/years following adjuvant therapy for early-stage breast cancer has received limited attention. Here, we discuss the risk and extent of CVD in breast cancer patients, review the pathogenesis of CVD, and highlight existing evidence from select clinical trials investigating the efficacy of structured exercise treatment across the CVD continuum in early breast cancer.

Anthracycline-containing chemotherapy (Anth-C) is associated with long-term cardiovascular mortality. Although cardiovascular risk assessment has traditionally focused on the heart, evidence has demonstrated that vascular dysfunction also occurs during and up to 1 year following Anth-C. Whether vascular dysfunction persists long-term or negatively influences cardiac function remains unknown. Hence, the present study evaluated ventricular-arterial coupling, in concert with measures of vascular structure and function, in the years following Anth-C.Arterial elastance (Ea), end-systolic elastance (Ees), and ventricular-arterial coupling (Ea/Ees) were measured during rest and exercise using echocardiography. Resting vascular function (flow-mediated dilation) and structure (carotid intima-media thickness, arterial stiffness) were also measured.Thirty breast cancer survivors (6.5 ± 3.6 years after Anth-C) with normal left ventricular ejection fraction (LVEF) (60% ± 6%) and 30 matched controls were studied. At rest, no differences were found in Ea, Ees, Ea/Ees, or LVEF between groups. The normal exercise-induced increase in Ees was attenuated in survivors at 50% and 75% of maximal workload (p.01). Ea/Ees was also higher at all workloads in the survivors compared with the controls (p.01). No differences in vascular structure and function were observed between the two groups (p.05).In the years after Anth-C, ventricular-arterial coupling was significantly attenuated during exercise, primarily owing to decreased LV contractility (indicated by a reduced Ees). This subclinical dysfunction appears to be isolated to the heart, as no differences in Ea were observed. The previously reported adverse effects of Anth-C on the vasculature appear to not persist in the years after treatment, as vascular structure and function were comparable to controls.Anthracycline-induced cardiotoxicity results in significantly impaired ventricular-arterial coupling in the years following chemotherapy, owing specifically to decreased left ventricular contractility. This subclinical dysfunction was identified only under exercise stress. A comprehensive evaluation of vascular structure and function yielded no differences between those treated with anthracyclines and controls. Combined with a stress stimulus, ventricular-arterial coupling might hold significant value beyond characterization of integrative cardiovascular function, in particular as a part of a risk-stratification strategy after anthracycline-containing chemotherapy. Although vascular function and structure were not different in this cohort, this does not undermine the importance of identifying vascular (dys)function in this population, because increases in net arterial load during exercise might amplify the effect of reductions in contractility on cardiovascular function after anthracycline-containing chemotherapy.

Conventional resting left ventricular ejection fraction (LVEF) assessments have limitations for detecting doxorubicin (DOX)-related cardiac dysfunction. Novel resting echocardiographic parameters, including 3-dimen-sional echocardiography (3DE) and global longitudinal strain (GLS), have potential for early identification of chemotherapy-related myocardial injury. Exercise “stress” is an established method to uncover impairments in cardiac function but has received limited attention in the adult oncology setting. We evaluated the utility of an integrated approach using 3DE, GLS, and exercise stress echocardiography for detecting subclinical cardiac dysfunction in early breast cancer patients treated with DOX-containing chemotherapy. Fifty-seven asymptomatic women with early breast cancer (mean 26 ± 22 months post-chemotherapy) and 20 sex-matched controls were studied. Resting left ventricular (LV) function was assessed by LVEF using 2-dimensional echocardiography (2DE) and 3DE and by GLS using 2-dimensional speckle-tracking echocardiography (2D-STE). After resting assessments, subjects completed cardiopulmonary exercise testing with stress 2DE. Resting LVEF was lower in patients than controls by 3DE (55 ± 4 vs. 59 ± 5 %; p = 0.005) but not 2DE (56 ± 4 vs. 58 ± 3 %; p = 0.169). 10 of 51 (20 %) patients had GLS greater than or equal to −17 %, which was below the calculated lower limit of normal (control mean 2SD); this patient subgroup had a mean 20 % impairment in GLS (−16.1 ± 0.9 vs. −20.1 ± 1.5 %; p < 0.001), despite similar LVEF by 2DE and 3DE compared to controls (p > 0.05). Cardiopulmonary function (VO2peak) was 20 % lower in patients than controls (p < 0.001). Exercise stress 2DE assessments of stroke volume (61 ± 11 vs. 69 ± 15 ml; p = 0.018) and cardiac index (2.3 ± 0.9 vs. 3.1 ± 0.8 1 min−1 m−2 mean increase; p = 0.003) were lower in patients than controls. Post-exercise increase in cardiac index predicted VO2peak (r = 0.429, p = 0.001). Resting 3DE, GLS, and exercise stress 2DE detect subclinical cardiac dysfunction not apparent with resting 2DE in post-DOX breast cancer patients.

The structure and function of the human vasculature is integral to the efficacy of the cardiovascular system. In particular, arteries function as both a reservoir to dampen oscillations from the pumping heart, as well as a conduit to transport blood to the periphery. With age and disease, alterations in the composition of the arterial wall can occur. This can result in arteries becoming more resistant to wall deformation, referred to as arterial stiffness, which can have significant implications for the development of cardiovascular disease. Due to the emergence of arterial stiffness as a measure of cardiovascular disease risk, a number of non-invasive techniques have been developed, which include the use of ultrasonic assessment. These techniques are highly effective, reliable, and well validated, and consider stiffness both locally (most commonly measured at the carotid artery) as well as regionally (most commonly measured through the aorta) in the arterial tree. The assessment of arterial stiffness is critical to our understanding of the overall vascular health, and is the focus of this chapter.