Retinopathy, Optic Neuropathy, and Cataract in Childhood Cancer Survivors Treated With Radiation Therapy: A PENTEC Comprehensive Review

Update on diagnosis and management of radiation retinopathy

PURPOSE OF REVIEW

Radiation retinopathy is a vision-threatening complication of radiotherapy involving the eye or surrounding structures. This review aims to summarize recent advances in understanding the incidence, risk factors, pathophysiology, and utilization of new diagnostic imaging tools for radiation retinopathy. It will also focus on the current prophylaxis approaches to prevent or delay the development of radiation-related side effects and treatment strategies once radiation retinopathy occurs.

RECENT FINDINGS

The incidence of radiation retinopathy is influenced by radiation dose, fractionation schedule, and patient-specific factors such as diabetes mellitus and hypertension. Advances in imaging techniques, including optical coherence tomography angiography (OCTA) and ultra-widefield fluorescein angiography (UWFA), have enhanced early detection by identifying subclinical retinal changes. Novel insights into pathophysiology suggest a role for endothelial damage, inflammation, and oxidative stress in disease progression. Prophylactic approaches, such as intravitreal antivascular endothelial growth factor (anti-VEGF) agents, have shown promise in reducing the onset of retinopathy in high-risk patients. Therapeutic options, including intravitreal anti-VEGF and corticosteroids, have demonstrated efficacy in managing macular edema and preserving vision. However, the outcomes remain variable, necessitating personalized treatment strategies. To address some of these unanswered questions, the Diabetic Retinopathy Clinical Research Network (DRCR) Protocol AL is currently enrolling patients and preparing to analyze the long-term effects of treating patients prophylactically with intravitreal faricimab or the 0.19 mg fluocinolone acetonide implant compared to observation, to identify which patients will benefit from which specific regimen, therefore moving towards a personalized approach for this condition as well.

SUMMARY

Radiation retinopathy remains a significant challenge in ophthalmology. Early recognition through advanced imaging and tailored interventions, including prophylaxis and treatment, are crucial for optimizing visual outcomes. Further research into underlying mechanisms and novel therapies is essential to reduce the burden of this condition and improve patient quality of life.

Practice Patterns of Reirradiation for Brain and Spinal Tumors-An International Survey From the Reirradiation Collaborative Group (ReCOG)

PURPOSE

An international workshop was convened by the Reirradiation Collaborative Group. We conducted a survey among the invited attendants to assess practice patterns of reirradiation for central nervous system tumors.

METHODS AND MATERIALS

A web-based survey regarding central nervous system reirradiation was distributed to an international group of radiation oncologists and medical physicists via email.

RESULTS

Sixty-six respondents from 20 countries completed at least one section of the survey. The most important clinical considerations were treatment goal, degree of overlap, and cumulative dose. Among technical challenges, uncertainties in tolerance of organs at risk (OARs), tissue recovery factors (TRFs) and dose accumulation ranked the highest. Most respondents (68%) used a planning OAR volume with 0 to 3 mm margin. Highly conformal radiation techniques were preferred, including stereotactic body radiation therapy for spine (85%), intensity modulated radiation therapy for adult primary brain tumors (93%), and intensity modulated radiation therapy (100%) and proton therapy (83%) for pediatric cases. Most performed dose accumulation (65%) and evaluated cumulative biological (ie, equieffective) dose (88%). Sixty-one percent preferred rigid registration, whereas 35% used deformable registration, most commonly in pediatric cases (67%). The most frequently used α/β value for OARs was 2 Gy (76%). There was no clear consensus on OAR tolerance for any disease site. Different dose metrics were used for evaluation, including Dmax (48%) and D0.1cc (48%). Most (79%) considered time intervals between radiation courses. For adult primary brain tumors and brain metastasis, 50% and 46% recommended against reirradiation within a short interval (3-6 months). Most respondents (52%) used time dependent TRFs.

CONCLUSIONS

Among respondents, there are substantial variations in approaches to reirradiation (eg, addition of systemic therapy) and uncertainties in technical implementation (eg, OAR tolerance, TRF, and dose accumulation). Future collaborative registry-based and prospective studies should help address these uncertainties.

Successful treatment of choroidal hemangiomas in Sturge-Weber syndrome using external beam radiotherapy

Sturge-Weber syndrome (SWS) is a rare congenital disorder with diverse manifestations, including diffuse choroidal hemangiomas causing visual impairment. This case report describes a 14-year-old girl with retinal detachment due to diffuse choroidal hemangioma, treated effectively using external beam radiation therapy (EBRT). The treatment achieved a significant 55% reduction in choroidal thickness after the first phase and near-complete remission after supplementary therapy. This case underscores EBRT's efficacy and highlights the potential of adaptive radiation strategies for managing complex SWS-related ocular complications. Early intervention remains crucial for optimizing patient outcomes.

Comparison of dosimetric parameters for predicting radiation-induced cataract in paediatric patients

INTRODUCTION

This study compared the predictive ability of radiation-induced cataract between maximum point dose of the lens (Lens Dmax) ≥7 Gy, mean lens dose (Lens Dmean) ≥7 Gy, Lens Dmax ≥10 Gy, and Lens Dmean ≥10 Gy.

METHODS

Patients aged 3-18 years received cranial irradiation or radiation therapy at head and neck area between January 2010 and December 2019 at our institute were included. Patients without baseline and/or follow-up eye examination were excluded. Receiver operating characteristic (ROC) curves identified potential predictors and Cox regression analysed correlations between potential factors and cataract occurrence.

RESULTS

Sixty-three patients (122 eyes) were analysed. Cataracts were detected in 14 eyes (11.5%). Median follow-up time was 4 years (range 0.5-10 years), with cataract developing in a median of 2.5 years (range 0.3-7 years). Three patients (21.4%) developed grade ≥3 cataract. Lens Dmean ≥10 Gy was associated with cataract formation.

CONCLUSION

Lens Dmean ≥10 Gy showed the highest ability for predicting radiation-induced cataract in paediatric patients. Net reclassification improvement (NRI) suggested that changing lens dose constraint from Dmax <7 Gy to Dmean <10 Gy would miss 7% of cataract cases but avoid 28% of unnecessary restrictions. Adopting a mean lens dose <10 Gy was suggested as a constraint for lens dose.

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.

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.

Radiation Dose-Volume-Response Relationships for Adverse Events in Childhood Cancer Survivors: Introduction to the Scientific Issues in PENTEC

At its very core, radiation oncology involves a trade-off between the benefits and risks of exposing tumors and normal tissue to relatively high doses of ionizing radiation. This trade-off is particularly critical in childhood cancer survivors (CCS), in whom both benefits and risks can be hugely consequential due to the long life expectancy if the primary cancer is controlled. Estimating the normal tissue-related risks of a specific radiation therapy plan in an individual patient relies on predictive mathematical modeling of empirical data on adverse events. The Pediatric Normal-Tissue Effects in the Clinic (PENTEC) collaborative network was formed to summarize and, when possible, to synthesize dose-volume-response relationships for a range of adverse events incident in CCS based on the literature. Normal-tissue clinical radiation biology in children is particularly challenging for many reasons: (1) Childhood malignancies are relatively uncommon-constituting approximately 1% of new incident cancers in the United States-and biologically heterogeneous, leading to many small series in the literature and large variability within and between series. This creates challenges in synthesizing data across series. (2) CCS are at an elevated risk for a range of adverse health events that are not specific to radiation therapy. Thus, excess relative or absolute risk compared with a reference population becomes the appropriate metric. (3) Various study designs and quantities to express risk are found in the literature, and these are summarized. (4) Adverse effects in CCS often occur 30, 50, or more years after therapy. This limits the information content of series with even very extended follow-up, and lifetime risk estimates are typically extrapolations that become dependent on the mathematical model used. (5) The long latent period means that retrospective dosimetry is required, as individual computed tomography-based radiation therapy plans gradually became available after 1980. (6) Many individual patient-level factors affect outcomes, including age at exposure, attained age, lifestyle exposures, health behaviors, other treatment modalities, dose, fractionation, and dose distribution. (7) Prospective databases with individual patient-level data and radiation dosimetry are being built and will facilitate advances in dose-volume-response modeling. We discuss these challenges and attempts to overcome them in the setting of PENTEC.