Liver Late Effects in Childhood Cancer Survivors Treated With Radiation Therapy: A PENTEC Comprehensive Review

Whole Abdominal Radiotherapy Is Tolerable and Effective in Children and Young Adults With Intra-Abdominal Sarcoma: A Canadian Sarcoma Research and Clinical Collaboration (CanSaRCC) Study

BACKGROUND

Whole abdominal radiotherapy (WART) is utilized in children, adolescents, and young adults with intra-abdominal sarcoma, but efficacy and toxicity are uncertain.

METHODS

Sarcoma patients diagnosed at ≤39 years of age between 1998 and 2023 who received WART were identified from a national registry. Patient and tumor characteristics, treatment, response, and survival outcomes were assessed.

RESULTS

Twenty patients with desmoplastic small round cell tumor (DSRCT) (n = 7), rhabdomyosarcoma (RMS) (n = 6), Ewing sarcoma, rhabdoid tumor, endometrial stromal tumor (each n = 1), and sarcoma not-otherwise-specified (NOS) (n = 4) were included. Among 17 patients who received WART as part of upfront therapy, 16 had abdominal metastatic disease (94.1%) (peritoneal deposits n = 9, malignant ascites n = 8 [including two with both peritoneal deposits and malignant ascites] and liver metastases n = 1), while one was initially localized. Median WART dose was 22.5 Gy (range: 10.5-30); median kidney and liver doses were 14.9 Gy (range: 7.7-20.7) and 21.0 Gy (range: 13.1-27.7), respectively. Three patients developed Grade 3 acute toxicity; diarrhea (n = 2) or elevated creatinine (n = 1); two RMS patients developed second malignancies. Two-year overall and progression-free survival estimates were 100% and 80% (95% confidence interval [CI]: 51.6%-100%) in RMS; 62.5% (95% CI: 32%-100%) and 50% (95% CI: 22.5%-100%) in DSRCT. Five-year cumulative incidence of abdominal recurrence was 33.3% (95% CI: 11.4%-57.3%) with WART failure in DSRCT (n = 2) and sarcoma NOS (n = 1). Three patients received WART following relapse; all recurred; two within the WART field.

CONCLUSIONS

WART is well tolerated among young sarcoma patients and provides meaningful local disease control when utilized in front-line adjuvant therapy.

Liver quad culture chip as a model for radiation injury research

Both cancer patients receiving radiotherapy and civilians in a mass casualty nuclear event may suffer from radiation induced damage to organ systems. Radiation induced liver disease (RILD) can cause acute and long-term organ dysfunction that potentially leads to death. The objective of this study was to ascertain the validity of a liver quad-culture chip, a micro-physiological system comprising primary human hepatocytes and non-parenchymal cells (NPCs), including liver sinusoidal endothelial cells, hepatic stellate cells (HSCs), and Kupffer cells, as a model for RILD. The radiation exposure to the chip model resulted in DNA damage and cellular senescence of hepatocytes and NPCs. We observed metabolic dysfunction, inflammation, endothelial dysfunction, and HSCs activation. Whole genome sequencing revealed gene alterations in pathways relevant to RILD, as well as the potential efficacy of N-acetylcysteine amide (NACA) against RILD. NACA exhibited the capacity to mitigate DNA damage and cellular senescence and decreased the impact of radiation exposure on other pathophysiological changes. CDKN1A and miR-34a-5p were validated as useful radiation response and treatment efficacy biomarkers. These findings highlight the potential of the liver quad-culture chip as an effective model for investigating the microenvironment in RILD and for evaluating the efficacy of therapeutic countermeasures and biomarkers.

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.

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.