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Radiation treatment of benign tumors in NF2-related-schwannomatosis: A national study of 266 irradiated patients showing a significant increase in malignancy/malignant progression.

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Evans, D Gareth 
Halliday, Dorothy 
Obholzer, Rupert 
Afridi, Shazia 
Forde, Claire 


BACKGROUND: Radiation treatment of benign tumors in tumor predisposition syndromes is controversial, but short-term studies from treatment centers suggest safety despite apparent radiation-associated malignancy being reported. We determined whether radiation treatment in NF2-related schwannomatosis patients is associated with increased rates of subsequent malignancy (M)/malignant progression (MP). METHODS: All UK patients with NF2 were eligible if they had a clinical/molecular diagnosis. Cases were NF2 patients treated with radiation for benign tumors. Controls were matched for treatment location with surgical/medical treatments based on age and year of treatment. Prospective data collection began in 1990 with addition of retrospective cases in 1969. Kaplan-Meier analysis was performed for malignancy incidence and survival. Outcomes were central nervous system (CNS) M/MP (2cm annualized diameter growth) and survival from index tumor treatment. RESULTS: In total, 1345 NF2 patients, 266 (133-Male) underwent radiation treatments between 1969 and 2021 with median first radiotherapy age of 32.9 (IQR = 22.4-46.0). Nine subsequent CNS malignancies/MPs were identified in cases with only 4 in 1079 untreated (P < .001). Lifetime and 20-year CNS M/MP was ~6% in all irradiated patients-(4.9% for vestibular schwannomas [VS] radiotherapy) versus <1% in the non-irradiated population (P < .001/.01). Controls were well matched for age at NF2 diagnosis and treatment (Males = 133%-50%) and had no M/MP in the CNS post-index tumor treatment (P = .0016). Thirty-year survival from index tumor treatment was 45.62% (95% CI = 34.0-56.5) for cases and 66.4% (57.3-74.0) for controls (P = .02), but was nonsignificantly worse for VS radiotherapy. CONCLUSION: NF2 patients should not be offered radiotherapy as first-line treatment of benign tumors and should be given a frank discussion of the potential 5% excess absolute risk of M/MP.


Funder: Dame Eleanor Peel Trust, Royal College of Surgeons of Edinburgh, and the BMA Foundation

Funder: NHS


MPNST, NF2, Radiotherapy, malignant transformation, schwannoma

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Neurooncol Adv

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Oxford University Press (OUP)
NIHR Manchester Biomedical Research Centre (IS-BRC-1215-20007)
Cancer Research UK ACED Alliance Early Detection Centre (C19941/A27859)