Blunted response to a growth hormone stimulation test is associated with unfavorable cardiovascular risk factor profile in childhood cancer survivors

Cardiovascular Toxicity in Patients Treated for Childhood Cancer: A Scientific Statement From the American Heart Association

The field of cardio-oncology has expanded over the past 2 decades to address the ever-increasing issues related to cardiovascular disease in patients with cancer and survivors. There is increasing recognition that nearly all cancer treatments pose some short- or long-term risk for development of cardiovascular disease and that pediatric patients with cancer may be especially vulnerable to cardiovascular disease because of young age at treatment and expected long life span afterward. Anthracycline chemotherapy and chest-directed radiotherapy are the most well-studied cardiotoxic therapies, and dose reduction, use of cardioprotection for anthracyclines, and modern radiotherapy approaches have contributed to improved cardiovascular outcomes for survivors. Newer treatments such as small-molecule inhibitors, antibody-based cytotoxic therapy, and immunotherapy have expanded options for previously difficult-to-treat cancers but have also revealed new cardiotoxic profiles. Application of effective surveillance strategies in patients with cancer and survivors has been a focus of practitioners and researchers, whereas the prevention and treatment of extant cardiovascular disease is still developing. Incorporation of new strategies in an equitable manner and appropriate transition from pediatric to adult care will greatly influence long-term health-related outcomes in the growing population of childhood cancer survivors at risk for cardiovascular disease.

Approach to the Patient: Case Studies in Pediatric Growth Hormone Deficiency and Their Management

CONTEXT

Pathologies attributed to perturbations of the GH/IGF-I axis are among the most common referrals received by pediatric endocrinologists.

AIM

In this article, distinctive cased-based presentations are used to provide a practical and pragmatic approach to the management of pediatric growth hormone deficiency (GHD).

CASES

We present 4 case vignettes based on actual patients that illustrate (1) congenital GHD, (2) childhood GHD presenting as failure to thrive, (3) childhood GHD presenting in adolescence as growth deceleration, and (4) childhood-onset GHD manifesting as metabolic complications in adolescence. We review patient presentation and a management approach that aims to highlight diagnostic considerations for treatment based on current clinical guidelines, with mention of new therapeutic and diagnostic modalities being used in the field.

CONCLUSION

Pediatric GHD is diverse in etiology and clinical presentation. Timely management has the potential not only to improve growth but can also ameliorate or even mitigate adverse metabolic outcomes, which can be directly attributed to a GH deficient state.

The Role of Follicle-stimulating Hormone in Vascular Dysfunction Observed in Hematopoietic Cell Transplant Recipients

Childhood cancer survivors who receive a hematopoietic cell transplantation (HCT) are at increased risk for follicle-stimulating hormone (FSH) abnormalities, which may have a substantial negative impact on vascular function. The purpose of this study was to examine the association of vascular function with FSH in HCT recipients, non-HCT recipients and healthy controls. The study included childhood cancer survivors who were HCT recipients (n=24) and non-HCT recipients (n=308), and a control group of healthy siblings (n=211) all between 9 and 18 years old. Vascular measures of carotid artery structure and function (compliance and distensibility), brachial artery flow-mediated dilation and endothelial-independent dilation were measured using ultrasound imaging. A fasting blood sample was collected to measure hormone levels. FSH was significantly higher in HCT recipients compared with non-HCT recipients and healthy controls (P<0.01). Carotid compliance and distensibility were significantly lower in HCT and non-HCT recipients compared with healthy controls (P<0.05). Higher FSH was associated with decreased carotid compliance (P<0.05). This study's results suggest that higher levels of FSH in HCT recipients may result in significant reductions in vascular function compared with non-HCT recipients and healthy controls. Therefore, gonadotropin endocrine dysfunction, particularly abnormal FSH levels, may be an underlying mechanism of vascular dysfunction.

Cardiovascular Risk Reduction in High-Risk Pediatric Patients: A Scientific Statement From the American Heart Association

This scientific statement presents considerations for clinical management regarding the assessment and risk reduction of select pediatric populations at high risk for premature cardiovascular disease, including acquired arteriosclerosis or atherosclerosis. For each topic, the evidence for accelerated acquired coronary artery disease and stroke in childhood and adolescence and the evidence for benefit of interventions in youth will be reviewed. Children and adolescents may be at higher risk for cardiovascular disease because of significant atherosclerotic or arteriosclerotic risk factors, high-risk conditions that promote atherosclerosis, or coronary artery or other cardiac or vascular abnormalities that make the individual more vulnerable to the adverse effects of traditional cardiovascular risk factors. Existing scientific statements and guidelines will be referenced when applicable, and suggestions for risk identification and reduction specific to each setting will be described. This statement is directed toward pediatric cardiologists, primary care providers, and subspecialists who provide clinical care for these young patients. The focus will be on management and justification for management, minimizing information on pathophysiology and epidemiology.

Comparison between euglycemic hyperinsulinemic clamp and surrogate indices of insulin sensitivity in children with growth hormone deficiency

OBJECTIVE

Data about the impact of growth hormone treatment (GHT) on insulin sensitivity in children are quite controversial, due to the different surrogate indices that have been used.

DESIGN

We evaluated insulin sensitivity through the euglycemic hyperinsulinemic clamp, considered the gold standard technique, in 23 children affected by growth hormone deficiency (GHD) at baseline and after 12months of GHT and in 12 controls with short stature at baseline, and we compared the clamp-derived index (M-value) with the most commonly used surrogate index of insulin sensitivity, as ISI Matsuda, and with circulating plasma markers of insulin sensitivity, as adiponectin and resistin levels.

RESULTS

At baseline, no significant difference in all metabolic parameters between GHD children and control subjects was found. After 12months of GHT, GHD children showed a significant increase in fasting insulin (p<0.001) and resistin (p=0.028) and a decrease in ISI Matsuda (p<0.001) and M-value (p<0.001), without significant change in fasting glucose, HbA1c and adiponectin. In GHD children, M-value showed a significant but weak correlation with ISI Matsuda (rho 0.418, p=0.047) at baseline, while no correlation with other parameters was found. After 12months of GHT, M-value did not show any significant correlation with any other metabolic parameter analyzed.

CONCLUSIONS

This study highlights the limit of the evaluation of insulin sensitivity performed through surrogate indices or circulating markers, which may lead to controversial data and do not correlate with the gold standard technique to evaluate insulin sensitivity.

Cardiovascular Complications of Cranial and Neck Radiation

OPINION STATEMENT

Cancer survivors who receive head and neck radiation are at increased risk for cerebrovascular events. This is mediated via damage to the hypothalamus-pituitary axis leading to the metabolic syndrome and extracranial arterial injury leading to carotid artery stenosis. Head and neck radiation can also lead to intracranial injury that can present as moyamoya, especially in children. Survivors require lifelong periodic follow-up for the development of pan-hypopituitarism or its individual components as well as for dyslipidemia and obesity. Aggressive control of traditional cardiovascular risk factors is recommended to reduce cardiovascular morbidity and mortality. There are no specific guidelines for the surveillance and management of asymptomatic carotid artery disease in cancer survivors. However, regular detailed examination for carotid bruits and neurological symptoms is recommended. Treatment of significant radiation-induced carotid artery disease has not been specifically studied and is based upon recommendations for patients with atherosclerotic carotid stenosis. Carotid endarterectomy can be difficult in radiation patients due to anatomic concerns and the risk of post-operative cranial nerve injury and wound complications but should be considered in patients with suitable anatomy and neck architecture. Carotid artery stenting, while successful, may be associated with greater long-term mortality and neurologic complications. Regardless of the strategy employed, radiation patients are at increased risk for restenosis and should undergo routine surveillance even after revascularization.

Premature Atherosclerotic Cardiovascular Disease in Childhood Cancer Survivors

Survival rates of childhood cancer have increased over the last 30 years, revealing a population with unique characteristics and risks. The effects of radiation and cardiotoxic chemotherapy predispose these children to both early and late cardiovascular disease. Cranial radiation also increases the likelihood of growth hormone deficiency, which leads to metabolic disturbances. Childhood cancer survivors are less likely to be active than their healthy siblings, and have a lower aptitude for physical activity. These issues are additive to the usual risks experienced by the general population, thereby significantly increasing the likelihood of premature cardiovascular disease. Early and regular screening and risk factor management in this population is recommended.

Modified Clonidine Testing for Growth Hormone Stimulation Reveals α2-Adrenoreceptor Sub Sensitivity in Children with Idiopathic Growth Hormone Deficiency

Introduction

The association between short stature and increased risk of ischemic heart disease has been subject to studies for decades. The recent discussion of cardiovascular risk during growth hormone therapy has given new importance to this question. We have hypothesized that the autonomic system is a crucial element relating to this subject.

Methods

Heart rate variability calculated from 24-hour electrocardiogram data is providing insight into the regulatory state of the autonomous nervous system and is an approved surrogate parameter for estimating cardiovascular risk. We have calculated heart rate variability during clonidine testing for growth hormone stimulation of 56 children. As clonidine is a well-known effector of the autonomous system, stimulating vagal tone and decreasing sympathetic activity, we compared the autonomous reactions of children with constitutional growth delay (CGD), growth hormone deficiency (GHD) and former small for gestational age (SGA).

Results

During clonidine testing children with CGD showed the expected α₂-adrenoreceptor mediated autonomous response of vagal stimulation for several hours. This vagal reaction was significantly reduced in the SGA group and nearly non- existent in the GHD group.

Discussion

Children with GHD show a reduced autonomous response to clonidine indicating α₂-adrenoreceptor sub sensitivity. This can be found prior to the start of growth hormone treatment. Since reduction of HRV is an approved surrogate parameter, increased cardiovascular risk has to be assumed for patients with GHD. In the SGA group a similar but less severe reduction of the autonomous response to clonidine was found. These findings may enrich the interpretation of the data on growth hormone therapy, which are being collected by the SAGhE study group.

Endocrine disorders in Fanconi anemia: recommendations for screening and treatment

CONTEXT

Endocrine problems are common in patients with Fanconi anemia (FA). About 80% of children and adults with FA have at least one endocrine abnormality, including short stature, GH deficiency, abnormal glucose or insulin metabolism, dyslipidemia, hypothyroidism, pubertal delay, hypogonadism, or impaired fertility. The goal of this report is to provide an overview of endocrine abnormalities and guidelines for routine screening and treatment to allow early diagnosis and timely intervention.

EVIDENCE ACQUISITION

This work is based on a comprehensive literature review, including relevant articles published between 1971 and 2014, and proceedings of a Consensus Conference held by the Fanconi Anemia Research Fund in 2013.

EVIDENCE SYNTHESIS

The panel of experts collected published evidence and discussed its relevance to reflect current information about the endocrine care of children and adults with FA before the Consensus Conference and through subsequent deliberations that led to the consensus.

CONCLUSIONS

Individuals with FA should be routinely screened for endocrine abnormalities, including evaluation of growth; glucose, insulin, and lipid metabolism; thyroid function; puberty; gonadal function; and bone mineral metabolism. Inclusion of an endocrinologist as part of the multidisciplinary patient care team is key to providing comprehensive care for patients with FA.

Hyperglycemia in patients with hematologic malignancies

Patients with hematologic malignancies are at high risk for hyperglycemia due to factors such as frequent exposure to glucocorticoids, immunosuppressants, total parenteral nutrition, and medical stress. Hyperglycemia in these patients has been associated with poor outcomes including increased risk of infection, organ dysfunction, durability of remission, graft-versus-host disease, and mortality. However, the appropriate glucose targets are not well established, and there are few prospective data assessing whether glucose control improves outcomes. HbA1c should be interpreted with caution in patients with hematologic malignancies, due to inaccuracies imposed by disordered hematopoiesis and frequent transfusions, and short-term perturbations imposed by acute illness or medications. Management of diabetes or glucocorticoid-induced hyperglycemia in the hospital generally requires insulin therapy, which is tailored based upon nutritional needs, baseline glucose control, and concomitant factors such as type and dose of glucocorticoid administration. Close follow-up and adjustment of therapy, ideally with the assistance of patient self-titration algorithms, is required after discharge. Patients are at increased long-term risk for developing diabetes and therefore should undergo regular screening.

Estimation of insulin sensitivity in children: methods, measures and controversies

Insulin resistance is defined as a state where insulin produces a diminished biological response, primarily in its capacity as a glucose-regulating hormone. Insulin resistance is commonly diagnosed by pediatric clinicians, but is rarely measured directly in children or adolescents. This review provides an overview of the techniques that can be used to assess insulin sensitivity in children, summarizing the methods involved, the assumptions, pitfalls, and appropriate uses of each technique, as well as their validation and reproducibility in pediatric samples.

Update on endocrine and metabolic therapy-related late effects observed in survivors of childhood neoplasia

PURPOSE OF REVIEW

To provide a summary of the most recent research pertaining to the endocrine and metabolic complications observed in childhood cancer survivors.

RECENT FINDINGS

Data on prevalence and risk associations are increasingly available from large cohorts of childhood cancer survivors. New directions in research include novel risk-prediction strategies and the study of genetic predisposition.

SUMMARY

Endocrine complications are observed in more than 50% of adult childhood cancer survivors. Some continue to develop decades following cancer treatment exposures. The present review provides a summary of the most recent outcomes research pertaining to growth, thyroid, gonadal-reproductive, bone and body composition with emphasis on new directions and challenges in each area.

Bone mineral deficits in recipients of hematopoietic cell transplantation: the impact of young age at transplant

Low bone mineral density (BMD) has been reported in recipients of pediatric hematopoietic cell transplantation (HCT), but it is unclear whether age at HCT plays a role. The objective of this cross-sectional study was to determine if patients treated with HCT before age 10 years have long-term BMD deficits compared to patients transplanted at an older age and to sibling controls. The study included 151 HCT recipients (87 males), age at study 24.7±8.6 years treated with HCT for hematologic malignancies at age 10.9±6.4 years, and 92 healthy sibling controls (49 males), age at study 22.3±8.0 years. Dual-energy x-ray absorptiometry was performed to measure BMD Z-scores for total body (TBMD), lumbar spine (LBMD), and femoral neck (FNBMD, for subjects ≥20 years at study visit). Patients <10 years at HCT had significantly lower TBMD and FNBMD Z-scores (by 0.5 and 0.8 SD, respectively) compared to controls (P=0.003 and P=0.0001, respectively) and patients >18 years at HCT (P=0.04 and P=0.004, respectively) at an average of 14 years after HCT. In conclusion, this study identified young age at transplant as an important risk factor for bone deficits in young adulthood, suggesting that efforts to reduce bone loss should focus on this patient population.