Visual decline in pediatric survivors of brain tumors following radiotherapy

Pediatric CNS Radiation Oncology: Recent Developments and Novel Techniques

Radiation therapy (RT) is a cornerstone in the management of pediatric central nervous system (CNS) tumors. Recent advancements in RT delivery and techniques aim to enhance therapeutic effectiveness while minimizing both acute and long-term complications associated with pediatric brain RT. This paper highlights innovative developments in the field, including the clinical indications, benefits, and challenges of proton therapy and stereotactic radiotherapy. The ongoing refinement of risk-adapted RT volumes is highlighted, with examples of newly proposed germinoma RT volumes and hippocampal-sparing RT. Additionally, emerging experimental approaches, including FLASH therapy and theranostics, are also discussed as promising future directions. Further prospective, multi-institutional collaborative studies are essential to validate and expand upon the benefits outlined in this review.

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

PURPOSE

Few reports describe the risks of late ocular toxicities after radiation therapy (RT) for childhood cancers despite their effect on quality of life. The Pediatric Normal Tissue Effects in the Clinic (PENTEC) ocular task force aims to quantify the radiation dose dependence of select late ocular adverse effects. Here, we report results concerning retinopathy, optic neuropathy, and cataract in childhood cancer survivors who received cranial RT.

METHODS AND MATERIALS

A systematic literature search was performed using the PubMed, MEDLINE, and Cochrane Library databases for peer-reviewed studies published from 1980 to 2021 related to childhood cancer, RT, and ocular endpoints including dry eye, keratitis/corneal injury, conjunctival injury, cataract, retinopathy, and optic neuropathy. This initial search yielded abstracts for 2947 references, 269 of which were selected as potentially having useful outcomes and RT data. Data permitting, treatment and outcome data were used to generate normal tissue complication probability models.

RESULTS

We identified sufficient RT data to generate normal tissue complication probability models for 3 endpoints: retinopathy, optic neuropathy, and cataract formation. Based on limited data, the model for development of retinopathy suggests 5% and 50% risk of toxicity at 42 and 62 Gy, respectively. The model for development of optic neuropathy suggests 5% and 50% risk of toxicity at 57 and 64 Gy, respectively. More extensive data were available to evaluate the risk of cataract, separated into self-reported versus ophthalmologist-diagnosed cataract. The models suggest 5% and 50% risk of self-reported cataract at 12 and >40 Gy, respectively, and 50% risk of ophthalmologist-diagnosed cataract at 9 Gy (>5% long-term risk at 0 Gy in patients treated with chemotherapy only).

CONCLUSIONS

Radiation dose effects in the eye are inadequately studied in the pediatric population. Based on limited published data, this PENTEC comprehensive review establishes relationships between RT dose and subsequent risks of retinopathy, optic neuropathy, and cataract formation.

Visual outcomes after treatment of craniopharyngioma in children: A systematic review

OBJECTIVE

Craniopharyngiomas (CP) are rare brain tumors that often result in visual impairment due to their proximity to the optic pathway. The optimal management approach to preserve visual function in these patients remains controversial. We sought to investigate visual outcomes of children with craniopharyngiomas based on treatment modality.

METHODS

A systematic review was performed according to PRISMA guidelines. PubMed, Embase, and Scopus databases were searched in December 2022 for relevant articles. Articles were screened by title/abstract for relevance, then by full-text. Relevant demographic, intervention, and outcome data were extracted from included studies.

RESULTS

A total of 59 studies were included, representing 2655 patients. The overall visual status (OVS) of patients receiving surgery alone was improved in 27.6% of reported outcomes, unchanged in 50.3%, and deteriorated in 22.1%. The OVS for patients receiving radiation alone was improved in 21.1%, unchanged in 42.1%, and deteriorated in 36.8%. Patients receiving surgery plus adjuvant radiotherapy had OVS improvement in 27.4%, unchanged in 63.2%, and deteriorated in 9.4%. Of those receiving intracystic bleomycin, 23.1% had improvement in OVS, 46.2% remained unchanged, and 30.8% deteriorated. Of patients receiving interferon-α, 34.8% improved, 54.5% remained unchanged, and 10.6% deteriorated.

CONCLUSION

OVS most frequently remained unchanged regardless of intervention. The greatest improvement in OVS was seen in those receiving interferon-α or surgery alone. The greatest OVS deterioration was noted with radiation alone. Future standardized, randomized, large-scale studies with focused assessment of ophthalmologic findings are key to further understanding the impact different interventions have on visual outcomes in these children.

Shifting Strategies in the Treatment of Pediatric Craniopharyngioma

PURPOSE OF REVIEW

Craniopharyngiomas represent one of the most challenging diseases to treat. Despite their benign histology, and after many decades of surgical experience and technological advancements, there is still no clear consensus regarding the most effective management for this tumor. Due to their location and aggressive local characteristics, purely surgical approaches all too often result in unacceptable morbidity.

RECENT FINDINGS

Partial resection combined with radiation therapy results in similar control rates when compared to aggressive surgery, while also minimalizing the neuro-endocrinological morbidity. In this manuscript, we describe the historical progression of the shifting strategies in the management of pediatric craniopharyngioma. Time has also altered our expectations for outcomes, evolving from purely morbidity and mortality to simple Glasgow Outcomes Scales, now to formal neuro-psychometric and quality of life data.

A case-control study of linear energy transfer and relative biological effectiveness related to symptomatic brainstem toxicity following pediatric proton therapy

BACKGROUND AND PURPOSE

A fixed relative biological effectiveness (RBE) of 1.1 (RBE_1.1) is used clinically in proton therapy even though the RBE varies with properties such as dose level and linear energy transfer (LET). We therefore investigated if symptomatic brainstem toxicity in pediatric brain tumor patients treated with proton therapy could be associated with a variable LET and RBE.

MATERIALS AND METHODS

36 patients treated with passive scattering proton therapy were selected for a case-control study from a cohort of 954 pediatric brain tumor patients. Nine children with symptomatic brainstem toxicity were each matched to three controls based on age, diagnosis, adjuvant therapy, and brainstem RBE_1.1 dose characteristics. Differences across cases and controls related to the dose-averaged LET (LET_d) and variable RBE-weighted dose from two RBE models were analyzed in the high-dose region.

RESULTS

LET_d metrics were marginally higher for cases vs. controls for the majority of dose levels and brainstem substructures. Considering areas with doses above 54 Gy(RBE_1.1), we found a moderate trend of 13% higher median LET_d in the brainstem for cases compared to controls (P = .08), while the difference in the median variable RBE-weighted dose for the same structure was only 2% (P = .6).

CONCLUSION

Trends towards higher LET_d for cases compared to controls were noticeable across structures and LET_d metrics for this patient cohort. While case-control differences were minor, an association with the observed symptomatic brainstem toxicity cannot be ruled out.