Chronic health conditions in childhood cancer survivors: is it all treatment-related--or do genetics play a role?

Genetic Risk of Second Malignant Neoplasm after Childhood Cancer Treatment: A Systematic Review

Second malignant neoplasm (SMN) is one of the most severe long-term risks for childhood cancer survivors (CCS), significantly impacting long-term patient survival. While radiotherapy and chemotherapy are known risk factors, the observed inter-individual variability suggests a genetic component contributing to the risk of SMN. This article aims to conduct a systematic review of genetic factors implicated in the SMN risk among CCS. Searches were performed in PubMed, Scopus, and Web of Sciences. Eighteen studies were included (eleven candidate gene studies, three genome-wide association studies, and four whole exome/genome sequencing studies). The included studies were based on different types of first cancers, investigated any or specific types of SMN, and focused mainly on genes involved in drug metabolism and DNA repair pathways. These differences in study design and methods used to characterize genetic variants limit the scope of the results and highlight the need for further extensive and standardized investigations. However, this review provides a valuable compilation of SMN risk-associated variants and genes, facilitating efficient replication and advancing our understanding of the genetic basis for this major risk for CCS.

Persistent variations of blood DNA methylation associated with treatment exposures and risk for cardiometabolic outcomes in long-term survivors of childhood cancer in the St. Jude Lifetime Cohort

BACKGROUND

It is well-established that cancer treatment substantially increases the risk of long-term adverse health outcomes among childhood cancer survivors. However, there is limited research on the underlying mechanisms. To elucidate the pathophysiology and a possible causal pathway from treatment exposures to cardiometabolic conditions, we conducted epigenome-wide association studies (EWAS) to identify the DNA methylation (DNAm) sites associated with cancer treatment exposures and examined whether treatment-associated DNAm sites mediate associations between specific treatments and cardiometabolic conditions.

METHODS

We included 2052 survivors (median age 33.7 years) of European ancestry from the St. Jude Lifetime Cohort Study, a retrospective hospital-based study with prospective clinical follow-up. Cumulative doses of chemotherapy and region-specific radiation were abstracted from medical records. Seven cardiometabolic conditions were clinically assessed. DNAm profile was measured using MethylationEPIC BeadChip with blood-derived DNA.

RESULTS

By performing multiple treatment-specific EWAS, we identified 935 5'-cytosine-phosphate-guanine-3' (CpG) sites mapped to 538 genes/regions associated with one or more cancer treatments at the epigenome-wide significance level (p < 9 × 10-8). Among the treatment-associated CpGs, 8 were associated with obesity, 63 with hypercholesterolemia, and 17 with hypertriglyceridemia (false discovery rate-adjusted p < 0.05). We observed substantial mediation by methylation at four independent CpGs (cg06963130, cg21922478, cg22976567, cg07403981) for the association between abdominal field radiotherapy (abdominal-RT) and risk of hypercholesterolemia (70.3%) and by methylation at three CpGs (cg19634849, cg13552692, cg09853238) for the association between abdominal-RT and hypertriglyceridemia (54.6%). In addition, three CpGs (cg26572901, cg12715065, cg21163477) partially mediated the association between brain-RT and obesity with a 32.9% mediation effect, and two CpGs mediated the association between corticosteroids and obesity (cg22351187, 14.2%) and between brain-RT and hypertriglyceridemia (cg13360224, 10.5%). Notably, several mediator CpGs reside in the proximity of well-established dyslipidemia genes: cg21922478 (ITGA1) and cg22976567 (LMNA).

CONCLUSIONS

In childhood cancer survivors, cancer treatment exposures are associated with DNAm patterns present decades following the exposure. Treatment-associated DNAm sites may mediate the causal pathway from specific treatment exposures to certain cardiometabolic conditions, suggesting the utility of DNAm sites as risk predictors and potential mechanistic targets for future intervention studies.

Current and coming challenges in the management of the survivorship population

With the widespread adoption of multimodality treatment, 5-year survival of children diagnosed with cancer has improved dramatically in the past several decades from approximately 60% in 1970 to greater than 85% currently. As a result, there are an estimated nearly half a million long-term survivors of childhood cancer living in the United States today. However, survivors have, on average, significantly greater serious medical and psychosocial late effects compared with the general population. In this review, we will discuss the current epidemiology of childhood cancer survivorship, including new methods to estimate the burden of late effects and genetic susceptibility toward late effects. We will also review the development of surveillance guidelines for childhood cancer survivors and early toxicity signals from novel agents now being tested and used increasingly to treat pediatric and adult cancers. We conclude with an overview of current models of survivorship care and areas for future research.

Health Status in Long-Term Survivors of Hepatoblastoma

The aim of this study was to evaluate the health status of children cured from hepatoblastoma. Forty-five patients with hepatoblastoma treated between 1996–2014 were assessed. The recorded data included sex, age at diagnosis, disease stage, treatment methods, time since diagnosis, and the evaluation of health status domains which included performance status, growth development, hearing, cardiovascular, skeletal, gastrointestinal, genitourinary, neurological, and hematological function. There were 30 boys and 15 girls. The age at diagnosis ranged from one month to 14 years (median one year). At the time of the health status evaluation, the youngest patient was 5.5 years old and the oldest was 21 years of age (median—10 years). All patients were treated according to the Childhood Liver Tumors Strategy Group—SIOPEL recommendations, though they were not active participants of the studies. The median cumulative dose of cisplatin was 520 mg/m² and 360 mg/m² for doxorubicin. Thirty-six patients underwent partial hepatectomy, and nine total hepatectomy and liver transplantation. At a median of nine years from diagnosis, 68% of hepatoblastoma survivors had experienced at least one chronic health condition of any grade. The most frequent late complication was ototoxicity (28.8%), and the most serious were second malignancies (6.6%) and cardiomyopathy (4.4%). Conclusion: Survivors of hepatoblastoma are at risk for long-term complications. They require long-term monitoring for late effects.

Prediction of cardiovascular disease among hematopoietic cell transplantation survivors

Cardiovascular disease (CVD) is a leading cause of late morbidity and mortality in hematopoietic cell transplantation (HCT) survivors. HCT-specific CVD risk prediction models are needed to facilitate early screening and prevention. In the current study, patients who underwent HCT at City of Hope (COH) and survived 1-year free of clinically evident CVD (N = 1828) were observed for the development of heart failure (HF) or coronary artery disease (CAD) by 10-years from index date (1 year from HCT). CVD occurred in 135 individuals (92 HF, 43 CAD). Risk prediction models were developed for overall CVD (HF and/or CAD) using COH-derived integer risk scores. Risk scores based on selected variables (age, anthracycline dose, chest radiation, hypertension, diabetes, smoking) achieved an area under the curve (AUC) and concordance (C) statistic of 0.74 and 0.72 for CVD; these varied from 0.70 to 0.82 according to CVD subtype (HF or CAD). A Fred Hutchinson Cancer Research Center case cohort (N = 580) was used to validate the COH models. Validation cohort AUCs ranged from 0.66 to 0.75. Risk scores were collapsed to form statistically distinct low-, intermediate-, and high-risk groups, corresponding to 10-year cumulative incidences of CVD of 3.7%, 9.9%, and 26.2%, respectively. Individuals in the high- and intermediate-risk groups were at 7.8-fold (95% confidence interval, 5.0-12.2) and 2.9-fold (95% confidence interval, 1.9-4.6) risk of developing CVD (referent group: low risk). These validated models provide a framework on which to modify current screening recommendations and for the development of targeted interventions to reduce the risk of CVD after HCT.

Optimizing Cardiovascular Care in Children With Acute Myeloid Leukemia to Improve Cancer-Related Outcomes

The Oncology Grand Rounds series is designed to place original reports published in the Journal into clinical context. A case presentation is followed by a description of diagnostic and management challenges, a review of the relevant literature, and a summary of the authors' suggested management approaches. The goal of this series is to help readers better understand how to apply the results of key studies, including those published in Journal of Clinical Oncology, to patients seen in their own clinical practice. A 14-year-old African American female presented with fatigue, easy bruising, and fever. On examination, she had scattered bruising, lymphadenopathy, and hepatosplenomegaly. Laboratory evaluation revealed pancytopenia with peripheral blasts, and acute myeloid leukemia (AML; French-American-British M2, t[8;21][q22;q22.1]) was diagnosed on bone marrow biopsy. A baseline echocardiogram revealed normal left ventricular (LV) systolic function (ejection fraction [EF], 60%; shortening fraction [SF], 32%), and conventional chemotherapy was initiated that consisted of two cycles of remission induction (cytarabine, etoposide, and daunorubicin [50 mg/m² × 3 days per cycle]) followed by intensification 1 (high-dose cytarabine and etoposide), intensification 2 (high-dose cytarabine and mitoxantrone [12 mg/m²/dose daily; four total doses]), and intensification 3 (high-dose cytarabine and l-asparaginase). Of note, an echocardiogram was not repeated before the start of intensification 1. During intensification 1, the patient developed Streptococcus viridans sepsis, which required 4 days in the intensive care unit with antimicrobial and inotropic support. Repeat echocardiogram after recovery from the sepsis episode demonstrated low-normal LV systolic function (EF, 53%; SF, 27%), and she subsequently began intensification 2. On day 3 of intensification 2, the patient developed afebrile tachypnea, tachycardia, and an increasing oxygen requirement. Chest x-ray revealed cardiomegaly and pulmonary vascular congestion. Cardiac troponins were normal, whereas N-terminal pro B-type natriuretic peptide was 10 times the upper limit of normal. Repeat echocardiogram showed an enlarged LV with moderate to severely depressed LV function (EF, 28%; SF, 14%). Day 4 mitoxantrone was omitted and a cardiology consult obtained.

Cardiovascular Disease in Survivors of Childhood Cancer: Insights Into Epidemiology, Pathophysiology, and Prevention

Cardiovascular disease (CVD), which includes cardiomyopathy/heart failure, coronary artery disease, stroke, pericardial disease, arrhythmias, and valvular and vascular dysfunction, is a major concern for long-term survivors of childhood cancer. There is clear evidence of increased risk of CVD largely attributable to treatment exposures at a young age, most notably anthracycline chemotherapy and chest-directed radiation therapy, and compounded by traditional cardiovascular risk factors accrued during decades after treatment exposure. Preclinical studies are limited; thus, it is a high priority to understand the pathophysiology of CVD as a result of anticancer treatments, taking into consideration the growing and developing heart. Recently developed personalized risk prediction models can provide decision support before initiation of anticancer therapy or facilitate implementation of screening strategies in at-risk survivors of cancer. Although consensus-based screening guidelines exist for the application of blood and imaging biomarkers of CVD, the most appropriate timing and frequency of these measures in survivors of childhood cancer are not yet fully elucidated. Longitudinal studies are needed to characterize the prognostic importance of subclinical markers of cardiovascular injury on long-term CVD risk. A number of prevention trials across the survivorship spectrum are under way, which include primary prevention (before or during cancer treatment), secondary prevention (after completion of treatment), and integrated approaches to manage modifiable cardiovascular risk factors. Ongoing multidisciplinary collaborations between the oncology, cardiology, primary care, and other subspecialty communities are essential to reduce therapeutic exposures and improve surveillance, prevention, and treatment of CVD in this high-risk population.

Evidence for Genetic Risk Contributing to Long-Term Adverse Treatment Effects in Childhood Cancer Survivors

Survivors of childhood cancer are at increased risk for therapy-related morbidities and mortality. Although the demographic and clinical factors predicting the risk for long-term effects of cancer therapy are well known, the impact of genetic risk for specific late effects is less clearly defined. Here, we review the extant literature and recent research describing genetic modifiers to risk for the more common late effects of childhood cancer therapy. Results of this research support the need for clinical trials that attempt to further refine risk prediction by incorporating genetic testing into existing algorithms that are primarily based on clinical and demographic factors. Confirmation of genetic predisposition, as defined by reproducibility and prospective validation, would permit therapeutic modification and discussion of individualized survivor care plans even at initial cancer diagnosis.

Cardiac Dysfunction and Heart Failure in Hematopoietic Cell Transplantation Survivors: Emerging Paradigms in Pathophysiology, Screening, and Prevention

Hematopoietic cell transplantation (HCT) has been used for curative intent in patients with hematologic and nonhematologic malignancies, resulting in an increasing number of HCT survivors. These survivors are at risk for serious and life-threatening complications, including cardiovascular disease (CVD). This article provides an overview of CVD in HCT survivors, describing the pathophysiology of disease, with a special emphasis on therapeutic exposures and comorbidities unique to this population. This article also discusses novel screening and prevention strategies that have shown promise in non-HCT cancer populations, emphasizing opportunities for collaboration between cardiologists and hematologists to improve the cardiovascular health of HCT survivors.

Collaborative Research in Childhood Cancer Survivorship: The Current Landscape

Survivors of childhood cancer carry a substantial burden of morbidity and are at increased risk for premature death. Furthermore, clear associations exist between specific therapeutic exposures and the risk for a variety of long-term complications. The entire landscape of health issues encountered for decades after successful completion of treatment is currently being explored in various collaborative research settings. These settings include large population-based or multi-institutional cohorts and single-institution studies. The ascertainment of outcomes has depended on self-reporting, linkage to registries, or clinical assessments. Survivorship research in the cooperative group setting, such as the Children's Oncology Group, has leveraged the clinical trials infrastructure to explore the molecular underpinnings of treatment-related adverse events, and to understand specific complications in the setting of randomized risk-reduction strategies. This review highlights the salient findings from these large collaborative initiatives, emphasizing the need for life-long follow-up of survivors of childhood cancer, and describing the development of several guidelines and efforts toward harmonization. Finally, the review reinforces the need to identify populations at highest risk, facilitating the development of risk prediction models that would allow for targeted interventions across the entire trajectory of survivorship.

Approaches to reduce the long-term burden of treatment-related complications in survivors of childhood cancer

Advances in diagnostics, treatment strategies, and supportive care have contributed to a marked improvement in outcomes for children with cancer. This has resulted in a growing number of long-term childhood cancer survivors. Currently there are over 360,000 individuals who are survivors of childhood cancer in the United States. However, treatment for patients with childhood cancer with chemotherapy, radiation, and/or hematopoietic stem cell transplantation can result in health-related complications that may not become evident until years after completion of treatment. As a result, several initiatives have been established to help standardize the surveillance for treatment-related late effects in childhood cancer survivors. This review highlights emerging concepts related to commonly reported late effects, such as subsequent malignant neoplasms, cardiovascular disease, and endocrinopathies. It also discusses relevant population-based screening strategies to mitigate the long-term health-related burden in vulnerable populations of survivors.

Children's Oncology Group's 2013 blueprint for research: survivorship and outcomes

Improvements in the treatment of childhood cancer have resulted in over 360,000 survivors of childhood cancer in the U.S. There is now a heightened recognition of the need to reduce treatment-related sequelae and optimize the quality of life of children treated for cancer. Survivorship studies conducted in the cooperative group setting have provided us with important information on long-term intellectual function, organ toxicity, reproductive outcomes, second cancers, late mortality, and disparities in outcomes. Ongoing health education initiatives have helped standardize the follow-up care for childhood cancer survivors and facilitate the early transfer of health-related information to patients, families, and healthcare providers.

Disparities in cancer outcomes: lessons learned from children with cancer

Disparities in cancer burden by race/ethnicity have been reported, primarily in adults with cancer. However, there appear to be gaps in the pediatric oncology literature with regards to a comprehensive overview on this topic. Extant literature is used to highlight the results of studies focusing on racial and ethnic disparities in outcome observed in selected childhood cancers. A comprehensive approach is utilized to understand possible underlying causes of disparities in cancer outcomes, and to highlight the gaps that currently exist. This review helps define areas of future research that could help develop targeted, disease-specific approaches to eliminate the disparities.