Radiation therapy dose escalation achieves high rates of local control with tolerable toxicity profile in pediatric and young adult patients with Ewing sarcoma

BACKGROUND

Local control for patients with Ewing sarcoma (EWS) who present with large tumors are suboptimal when treated with standard radiation therapy (RT) doses of 54-55.8 Gy. The purpose of this study is to determine local control and toxicity of dose-escalated RT for tumors ≥8 cm (greatest diameter at diagnosis) in pediatric and young adult patients with EWS.

METHODS

Eligible patients ≤30 years old with newly diagnosed EWS ≥8 cm treated with definitive conformal or intensity modulated photon, or proton radiation therapy techniques were included. All patients in the study received dose-escalated RT doses. Outcomes included overall survival (OS), event-free survival (EFS), local failure rates, and toxicity.

RESULTS

Thirty-two patients were included, 20 patients presented with metastatic disease and 12 patients with localized disease. The median RT dose was 64.8 Gy (range, 59.4-69.4 Gy) with variability of doses to protect normal surrounding tissues. All patients received systemic chemotherapy. The 5-year OS and EFS for the cohort was 64.2% and 42%, respectively. The 5-year cumulative incidence of local failure was 6.6%. There were two combined local and distant failures with no isolated local failures. Twenty-nine patients experienced short term toxicity, 90% of those being radiation dermatitis. Twenty-seven patients experienced long-term toxicity, with only one experiencing grade 4 toxicity, a secondary malignancy after therapy.

CONCLUSION

This study demonstrates that definitive RT for pediatric and young adult patients with EWS ≥8 cm provides high rates of local control, while maintaining a tolerable toxicity profile.

Novel MED15::ATF1 fusion in a pediatric melanoma with spitzoid features and aggressive presentation

Childhood melanoma is a rare and biologically heterogeneous pediatric malignancy. The differential diagnosis of pediatric melanoma is usually broad, including a wide variety of spindle cell or epithelioid neoplasms. Different molecular alterations affecting the MAPK and PI3K/AKT/mTOR pathways, tumor suppressor genes, and telomerase reactivation have been implicated in melanoma tumorigenesis and progression. Here, we report a novel MED15::ATF1 fusion in a pediatric melanoma with spitzoid features and an aggressive clinical course.

Addressing adherence to guidelines on prevention of acute chemotherapy-induced nausea and vomiting in pediatric patients

BACKGROUND

Chemotherapy-induced nausea and vomiting (CINV) is a distressing adverse effect in children receiving cancer treatment. There are evidence-based pediatric clinical practice guidelines (CPG) on chemotherapy emetogenicity and acute CINV prevention, but adherence to these guidelines is low.

PROCEDURE

A quality improvement-based study was conducted at McMaster Children's Hospital. The SMART aim was to increase adherence to guidelines on prevention of acute CINV in hospitalized patients receiving high (HEC) and moderately emetogenic chemotherapy (MEC) from baseline 25% to more than 70% by June 2021. Barriers were identified by process mapping, and a series of interventions were implemented.

RESULTS

Guideline adherence was assessed in 270 inpatient chemotherapy administrations (HEC, MEC). Data were collected on 131 charts pre interventions and 139 charts post interventions. Interventions included education, addition of guideline-recommended anti-emetics to the inpatient formulary, and implementation of a standardized CPG tool. Initial rates of total CINV guideline adherence were 25%, which improved to 72% post intervention (p < .001). In subgroup analysis, guideline adherence in the MEC group improved from 13% to 34% (p = .015), and in the HEC group from 32% to 93% (p < .001). The most common reason for nonadherence in the HEC group was failure to use aprepitant as anti-emetic, and in MEC was option for ondansetron monotherapy prophylaxis.

CONCLUSION

Using quality improvement methodology, barriers to guideline adherence were identified and interventions implemented. Guideline adherence for prevention of CINV improved, particularly in the HEC group but less for the MEC group. Future steps will include sustainability of interventions and addressing adherence in the MEC group.

Progressive metastatic infantile fibrosarcoma with multiple acquired mutations

Infantile fibrosarcoma is the most common soft tissue sarcoma in children under the age of 1 year and is defined molecularly by NTRK fusion proteins. This tumor is known to be locally invasive; however, metastasis are rare. The NTRK fusion acts as a driver for tumor formation which can be targeted by first and second generation NTRK inhibitors. While NTRK gatekeeper mutations have been well described as mechanisms of resistance to these agents, alternative pathway acquired mutations are rare. Here we report the case of a patient with infantile sarcoma treated with chemotherapy and NTRK inhibition that developed metastatic, progressive disease with multiple acquired mutations, including TP53, SUFU, and an NTRK F617L gatekeeper mutation. Alterations in pathways of SUFU and TP53 have been widely described in the literature in other tumors, however, not yet in infantile fibrosarcoma. While most patients have a sustained response to TRK inhibitors, a subset will go on to develop mechanisms of resistance that have implications for clinical management, such as in our patient. We hypothesize this constellation of mutations contributed to the patient's aggressive clinical course. Taken together, we report the first case of infantile fibrosarcoma with ETV6::NTRK3 and acquired SUFU, TP53, and NTRK F617L gatekeeper mutation along with detailed clinical course and management. Our report highlights the importance of genomic profiling in recurrent infantile fibrosarcoma to reveal actionable mutations, such as gatekeeper mutations, that can improve patient outcomes.

A Case of a Pediatric Patient With Protein S Heerlen Polymorphism and Deep Venous Thrombosis

Hereditary protein S (PS) deficiency is a rare autosomal dominant disorder with increased risk of venous thromboembolism. The PS Heerlen polymorphism at codon 501 of the PROS1 gene is considered a variant of uncertain significance. It has since been shown that PS Heerlen has a reduced half-life, resulting in reduced levels of free PS. We report a case of an adolescent female with May Thurner syndrome and heterozygous PS Heerlen mutation resulting in a mild PS deficiency and venous thromboembolism. With this nonmodifiable risk factor, the patient received prolonged anticoagulation with strong consideration for lifelong prophylaxis.

Female genitalia hydatidosis herniating to the inguinal canal

Hydatid disease of the female genitalia presents a rare problem in gynecology formerly limited to only a few parts of the world. Primary pelvic hydatidosis is uncommon, and its pathogenesis remains unclear. We report one case of primary hydatid cysts and another case of secondary hydatid cysts of the female genitalia that herniated to the inguinal canal.

Retrobulbar hydatid cyst: assessment of two cases

A 54-year-old man with a unilocular hydatid cyst within the infero-posterior angle of the orbit and a 6-year-old male child with a unilocular hydatid cyst within the supero-medial angle of the orbit are presented. The retrobulbar cysts were diagnosed with computed tomography and ultrasonography and were treated after serologic confirmation.