Effects of Radiation Therapy on the Female Reproductive Tract in Childhood Cancer Survivors: A PENTEC Comprehensive Review

Fertility Preservation in People With Cancer: ASCO Guideline Update

PURPOSE

To provide updated fertility preservation (FP) recommendations for people with cancer.

METHODS

A multidisciplinary Expert Panel convened and updated the systematic review.

RESULTS

One hundred sixty-six studies comprise the evidence base.

RECOMMENDATIONS

People with cancer should be evaluated for and counseled about reproductive risks at diagnosis and during survivorship. Patients interested in or uncertain about FP should be referred to reproductive specialists. FP approaches should be discussed before cancer-directed therapy. Sperm cryopreservation should be offered to males before cancer-directed treatment, with testicular sperm extraction if unable to provide semen samples. Testicular tissue cryopreservation in prepubertal males is experimental and should be offered only in a clinical trial. Males should be advised of potentially higher genetic damage risks in sperm collected soon after cancer-directed therapy initiation and completion. For females, established FP methods should be offered, including embryo, oocyte, and ovarian tissue cryopreservation (OTC), ovarian transposition, and conservative gynecologic surgery. In vitro maturation of oocytes may be offered as an emerging method. Post-treatment FP may be offered to people who did not undergo pretreatment FP or cryopreserve enough oocytes or embryos. Gonadotropin-releasing hormone agonist (GnRHa) should not be used in place of established FP methods but may be offered as an adjunct to females with breast cancer. For patients with oncologic emergencies requiring urgent oncologic therapy, GnRHa may be offered for menstrual suppression. Established FP methods in children who have begun puberty should be offered with patient assent and parent/guardian consent. The only established method for prepubertal females is OTC. Oncology teams should ensure prompt access to a multidisciplinary FP team. Clinicians should advocate for comprehensive FP services coverage and help patients access benefits.Additional information is available at www.asco.org/survivorship-guidelines.

Use of Virtual CT and On-Treatment MRI to Reduce Radiation Dose and Anesthesia Exposure Associated With the Adaptive Workflow in Pediatric Patients Treated With Intensity Modulated Proton Therapy

Purpose

The purpose of this study was to determine whether virtual computed tomography (vCT) derived from daily cone beam computed tomography (CBCT), or on-treatment magnetic resonance imaging (MRItx) can replace quality assurance computed tomography (qCT) in our clinical workflow to minimize imaging dose and potentially anesthesia exposure in patients requiring plan adaptation.

Methods and Materials

Pediatric patients (age <24 years) treated from 2020 to 2023 with intensity modulated proton therapy with at least 1 qCT during proton therapy were eligible. For cases that required plan adaptation, the dose was recalculated on vCT and compared with same-day qCT as well as the original planning computed tomography (pCT). Anatomic changes triggering plan adaptation were grouped into categories. Two pediatric radiation oncologists verified whether these changes could be detected using CBCT, qCT, and/or MRItx. A new adaptive imaging workflow was proposed to limit imaging dose and anesthesia exposure.

Results

One hundred sixty-eight pediatric patients were treated from 2020 to 2023. Across all patients, there were 517 qCT scans and 61 MRItx acquired. The median number of qCT scans per patient was 3 (range, 1-5). The treatment plans for 20 patients (12%) were adapted. In all patients requiring plan adaptation, there was a correlation between dose differences in target coverage and maximum body dose when comparing vCT with pCT and qCT with pCT (n = 20, r2 = 0.79, P < .01, and r2 = 0.32 P = .01, respectively). The most common reason for adaptation was tissue change (eg, inflammation, changes in abdominal gas, or diaphragmatic variability) in the beam path (10/20) and changes in tumor volume (6/20). All cases of weight change, tissue change in beam path, and unreproducible setup could be detected on CBCT. All cases of change in tumor volume within the brain were detected on MRItx. Replacing the qCT with the vCT was associated with an estimated median reduction of imaging dose by 50% and anesthesia exposure by 1.5 hours.

Conclusions

vCT derived from daily CBCT only or MRItx can safely replace qCT for monitoring dosimetric changes to trigger a new pCT in our clinical workflow. This change would potentially reduce imaging dose and anesthesia exposure.

Premature ovarian insufficiency

Premature ovarian insufficiency (POI) is a cause of infertility and endocrine dysfunction in women, defined by loss of normal, predictable ovarian activity before the age of 40 years. POI is clinically characterized by amenorrhoea (primary or secondary) with raised circulating levels of follicle-stimulating hormone. This condition can occur due to medical interventions such as ovarian surgery or cytotoxic cancer therapy, metabolic and lysosomal storage diseases, infections, chromosomal anomalies and autoimmune diseases. At least 1 in 100 women is affected by POI, including 1 in 1,000 before the age of 30 years. Substantial evidence suggests a genetic basis to POI. However, the cause of idiopathic POI remains unknown in most patients, indicating that gene variants associated with this condition remain to be discovered. Over the past 10 years, tremendous progress has been made in our knowledge of genes involved in POI. Genetic approaches in diagnosis are important as they enable patients with familial POI to be identified, with the opportunity for oocyte preservation. Moreover, genetic approaches could provide a better understanding of disease mechanisms, which will ultimately aid the development of improved treatments.

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.

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.