Management of Ganglioneuroma and Ganglioneuroblastoma Intermixed: A United Kingdom Children's Cancer and Leukaemia Group (UK CCLG) Nationwide Study Report.

Background: Ganglioneuroblastoma intermixed (GNBi) and ganglioneuroma (GN) represent benign variants of peripheral neuroblastic tumours. While historically surgical resection was recommended, watchful active observation has become the accepted management for a subset of patients.

Objectives: To review clinical features, biology, natural history and management of a retrospective UK CCLG study cohort of GN and GNBi, and compare outcomes of patients treated with surgical resection or watchful active observation.

Methods: Retrospective review of histologically confirmed non-metastatic GN and GNBi diagnosed between 1990 and 2020.

Results: A total of 259 patients were identified (163 GN, 93 GNBi, median age 62 months). In all 201 (78%) had initial surgery and 58 (22%) were observed. Overall survival was 98%. Twenty-one of 58 observed (36%) required subsequent surgery due to progressive tumour growth (52%). Gross total resection (GTR) was achieved in 79% of patients with a 19% complication rate. GTR was obtained in a similar proportion of patients having initial surgery (65%) and delayed surgery (76%). Patients obtaining GTR were more likely to have complete symptom(s) control (43% vs. 24%). In 45 cases (39%), surgical pathology was different from pathology at biopsy, and in 14 (12%) the pathology changed from GN/GNBi to neuroblastoma/GNB nodular.

Conclusion: Watchful active observation can be a safe approach, with surgical resection reserved for symptomatic patients. However, a small proportion of patients in the observation group had their diagnosis revised to malignant at surgery. Careful assessment of surgical risk and expected benefits, after considering an initial period of observation, will allow clinicians to make optimal decisions for patients and their families.