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Disease course of Neurofibromatosis Type 2; a 30-year follow-up study of 353 patients seen at a single institution.

BACKGROUND
Limited data exists on the disease course of Neurofibromatosis Type 2 (NF2) to guide clinical trial design.


METHODS
A prospective database of patients meeting NF2 diagnostic criteria, reviewed between 1990-2020, was evaluated. Follow-up to first vestibular schwannoma (VS) intervention and death was assessed by univariate analysis and stratified by age at onset, era referred and inheritance type. Interventions for NF2-related tumours were assessed. Cox regression was performed to determine the relationship between individual factors from time of diagnosis to NF2-related death.


RESULTS
Three-hundred-and-fifty-three patients were evaluated. During 4643.1 follow-up years from diagnosis to censoring 60 patients (17.0%) died. The annual mean number of patients undergoing VS surgery or radiotherapy declined, from 4.66 and 1.65 respectively per 100 NF2 patients in 1990-1999 to 2.11 and 1.01 in 2010-2020, as the number receiving bevacizumab increased (2.51 per 100 NF2 patients in 2010-2020). Five patients stopped bevacizumab to remove growing meningioma or spinal schwannoma. 153/353 (43.3%) had at least one neurosurgical intervention/radiation treatment within 5 years of diagnosis. Patients asymptomatic at diagnosis had longer time to intervention and better survival compared to those presenting with symptoms. Those symptomatically presenting <16 and >40 years had poorer overall survival than those presenting at 26-39 years (P=0.03 and P=0.02 respectively) but those presenting between 16-39 had shorter time to VS intervention. Individuals with de novo constitutional variants had worse survival than those with de novo mosaic or inherited disease (P=0.004).


CONCLUSION
Understanding disease course improves prognostication, allowing for better informed decisions about care.