Cardiac Disease in Childhood Cancer Survivors Treated With Radiation Therapy: A PENTEC Comprehensive Review

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.

Proton therapy for pediatric malignancies: Indications and challenges focusing on the oncological landscape

Advances in therapeutic techniques and multimodal approaches have significantly improved the success rates of treatment for pediatric malignancies, with cure rates now close to 80%. This has led to an increase in long-term survival, with 0.10-0.15% of the general population being survivors of childhood cancer. In Italy, cancer registry data suggest that 75% of treated children become long-term survivors. However, these survivors face significant risks of late adverse events, including chronic diseases and severe conditions, highlighting the need for specialized follow-up care.Radiotherapy, a cornerstone of pediatric cancer treatment, contributes to late toxicities due to the susceptibility of growing tissues. Proton therapy offers advantages in reducing treatment-related toxicity, reducing the risk of secondary cancers, and allowing dose escalation for radioresistant tumors. Comparative studies suggest that proton therapy is superior in sparing healthy tissues and reducing long-term toxicities.Despite these benefits, challenges such as the high cost, limited proton therapy centers, and the need for clinical trials hinder the widespread adoption of proton therapy. Efforts to centralize care in high-ranking centers and ensure equitable access to proton therapy are crucial. In Italy, pediatric solid tumors are now eligible for proton therapy under national health policies, ensuring free access for all children.Dedicated proton therapy centers must provide comprehensive care involving multidisciplinary teams and supportive environments for pediatric patients and their families. Addressing current limitations and enhancing care environments are essential for improving outcomes for pediatric oncology patients.

Treatments affecting splenic function as a risk factor for valvular heart disease in Childhood Cancer Survivors: A DCCSS-LATER study

PURPOSE

Splenectomy might be a risk factor for valvular heart disease (VHD) in adult Hodgkin lymphoma survivors. As this risk is still unclear for childhood cancer survivors (CCS), the aim of this study is to evaluate the association between treatments affecting splenic function (splenectomy and radiotherapy involving the spleen) and VHD in CCS.

METHODS

CCS were enrolled from the DCCSS-LATER cohort, consisting of 6,165 five-year CCS diagnosed between 1963 and 2002. Symptomatic VHD, defined as symptoms combined with a diagnostic test indicating VHD, was assessed from questionnaires and validated using medical records. Differences in the cumulative incidence of VHD between CCS who received treatments affecting splenic function and CCS who did not were assessed using the Gray test. Risk factors were analyzed in a multivariable Cox proportional hazards model.

RESULTS

The study population consisted of 5,286 CCS, with a median follow-up of 22 years (5-50 years), of whom 59 (1.1%) had a splenectomy and 489 (9.2%) radiotherapy involving the spleen. VHD was present in 21 CCS (0.4%). The cumulative incidence of VHD at the age of 40 years was significantly higher in CCS who received treatments affecting splenic function (2.7%, 95% confidence interval (CI) 0.4%-4.9%) compared with CCS without (0.4%, 95% CI 0.1%-0.7%) (Gray's test, p = 0.003). Splenectomy was significantly associated with VHD in a multivariable analysis (hazard ratio 8.6, 95% CI 3.1-24.1).

CONCLUSIONS AND IMPLICATIONS

Splenectomy was associated with VHD. Future research is needed to determine if CCS who had a splenectomy as part of cancer treatment might benefit from screening for VHD.

Comparison of Risks of Late Effects From Radiation Therapy in Children Versus Adults: Insights From the QUANTEC, HyTEC, and PENTEC Efforts

Pediatric Normal Tissue Effects in the Clinic (PENTEC) seeks to refine quantitative radiation dose-volume relationships for normal-tissue complication probabilities (NTCPs) in survivors of pediatric cancer. This article summarizes the evolution of PENTEC and compares it with similar adult-focused efforts (eg, Quantitative Analysis of Normal Tissue Effects in the Clinic [QUANTEC] and Hypofractionated Treatment Effects in the Clinic [HyTEC]) with respect to content, oversight, support, scope, and methodology of literature review. It then summarizes key organ-specific findings from PENTEC in an attempt to compare NTCP estimates in children versus adults. In brief, select normal-tissue risks within developing organs and tissues (eg, maldevelopment of musculoskeletal tissue, teeth, breasts, and reproductive organs) are primarily relevant only in children. For some organs and tissues, children appear to have similar (eg, brain for necrosis, optic apparatus, parotid gland, liver), greater (eg, brain for neurocognition, cerebrovascular, breast for lactation), less (ovary), or perhaps slightly less (eg, lung) risks of toxicity versus adults. Similarly, even within the broad pediatric age range (including adolescence), for some endpoints, younger children have greater (eg, hearing and brain for neurocognition) or lesser (eg, ovary, thyroid) risks of radiation-associated toxicities. NTCP comparisons in adults versus children are often confounded by marked differences in treatment paradigms that expose normal tissues to radiation (ie, cancer types, prescribed radiation therapy dose and fields, and chemotherapy agents used). To add to the complexity, it is unclear if age is best analyzed as a continuous variable versus with age groupings (eg, infants, young children, adolescents, young adults, middle-aged adults, older adults). Further work is needed to better understand the complex manner in which age and developmental status affect risk.

A User's Guide and Summary of Pediatric Normal Tissue Effects in the Clinic (PENTEC): Radiation Dose-Volume Response for Adverse Effects After Childhood Cancer Therapy and Future Directions

Pediatric Normal Tissue Effects in the Clinic (PENTEC) is an international multidisciplinary effort that aims to summarize normal-tissue toxicity risks based on published dose-volume data from studies of children and adolescents treated with radiation therapy (RT) for cancer. With recognition that children are uniquely vulnerable to treatment-related toxic effects, our mission and challenge was to assemble our group of physicians (radiation and pediatric oncologists, subspecialists), physicists with clinical and modeling expertise, epidemiologists, and other scientists to develop evidence-based radiation dosimetric guidelines, as affected by developmental status and other factors (eg, other cancer therapies and host factors). These quantitative toxicity risk estimates could serve to inform RT planning and thereby improve outcomes. Tandem goals included the description of relevant medical physics issues specific to pediatric RT and the proposal of dose-volume outcome reporting standards to inform future studies. We created 19 organ-specific task forces and methodology to unravel the wealth of data from heterogeneous published studies. This report provides a high-level summary of PENTEC's genesis, methods, key findings, and associated concepts that affected our work and an explanation of how our findings may be interpreted and applied in the clinic. We acknowledge our predecessors in these efforts, and we pay homage to the children whose lives informed us and to future generations who we hope will benefit from this additional step in our path forward.

Imaging Assessment of Radiation Therapy-Related Normal Tissue Injury in Children: A PENTEC Visionary Statement

The Pediatric Normal Tissue Effects in the Clinic (PENTEC) consortium has made significant contributions to understanding and mitigating the adverse effects of childhood cancer therapy. This review addresses the role of diagnostic imaging in detecting, screening, and comprehending radiation therapy-related late effects in children, drawing insights from individual organ-specific PENTEC reports. We further explore how the development of imaging biomarkers for key organ systems, alongside technical advancements and translational imaging approaches, may enhance the systematic application of imaging evaluations in childhood cancer survivors. Moreover, the review critically examines knowledge gaps and identifies technical and practical limitations of existing imaging modalities in the pediatric population. Addressing these challenges may expand access to, minimize the risk of, and optimize the real-world application of, new imaging techniques. The PENTEC team envisions this document as a roadmap for the future development of imaging strategies in childhood cancer survivors, with the overarching goal of improving long-term health outcomes and quality of life for this vulnerable population.

Improving Pediatric Normal Tissue Radiation Dose-Response Modeling in Children With Cancer: A PENTEC Initiative

The development of normal tissue radiation dose-response models for children with cancer has been challenged by many factors, including small sample sizes; the long length of follow-up needed to observe some toxicities; the continuing occurrence of events beyond the time of assessment; the often complex relationship between age at treatment, normal tissue developmental dynamics, and age at assessment; and the need to use retrospective dosimetry. Meta-analyses of published pediatric outcome studies face additional obstacles of incomplete reporting of critical dosimetric, clinical, and statistical information. This report describes general methods used to address some of the pediatric modeling issues. It highlights previous single- and multi-institutional pediatric dose-response studies and summarizes how each PENTEC taskforce addressed the challenges and limitations of the reviewed publications in constructing, when possible, organ-specific dose-effect models.

Reporting Standards for Complication Studies of Radiation Therapy for Pediatric Cancer: Lessons From PENTEC

The major aim of Pediatric Normal Tissue Effects in the Clinic (PENTEC) was to synthesize quantitative published dose/-volume/toxicity data in pediatric radiation therapy. Such systematic reviews are often challenging because of the lack of standardization and difficulty of reporting outcomes, clinical factors, and treatment details in journal articles. This has clinical consequences: optimization of treatment plans must balance between the risks of toxicity and local failure; counseling patients and their parents requires knowledge of the excess risks encountered after a specific treatment. Studies addressing outcomes after pediatric radiation therapy are particularly challenging because: (a) survivors may live for decades after treatment, and the latency time to toxicity can be very long; (b) children's maturation can be affected by radiation, depending on the developmental status of the organs involved at time of treatment; and (c) treatment regimens frequently involve chemotherapies, possibly modifying and adding to the toxicity of radiation. Here we discuss: basic reporting strategies to account for the actuarial nature of the complications; the reporting of modeling of abnormal development; and the need for standardized, comprehensively reported data sets and multivariate models (ie, accounting for the simultaneous effects of radiation dose, age, developmental status at time of treatment, and chemotherapy dose). We encourage the use of tools that facilitate comprehensive reporting, for example, electronic supplements for journal articles. Finally, we stress the need for clinicians to be able to trust artificial intelligence models of outcome of radiation therapy, which requires transparency, rigor, reproducibility, and comprehensive reporting. Adopting the reporting methods discussed here and in the individual PENTEC articles will increase the clinical and scientific usefulness of individual reports and associated pooled analyses.