Malignant peripheral nerve sheath tumours in neurofibromatosis 1

TLDR

Cross‑sectional studies report that 1–2 % of neurofibromatosis 1 patients develop malignant peripheral nerve sheath tumours, yet no population‑based longitudinal studies have quantified their lifetime risk. The study identified NF1 patients with MPNST in north‑west England over 1984–1996 by linking the North West Regional NF1 Register with the regional cancer registry and reviewing patient notes. In a 13‑year population‑based study of 4.1 million residents, 21 NF1 patients developed MPNST (annual incidence 1.6/1000, lifetime risk 8–13 %), with a median diagnosis age of 26 versus 62 for sporadic cases, 5‑year survival of 21 % versus 42 %, and one patient presenting two tumors in a prior radiation field, indicating a markedly higher lifetime risk that justifies vigilant surveillance and prompt investigation.

Abstract

<b>Background:</b> Cross sectional studies have shown that 1-2% of patients with neurofibromatosis 1 (NF1) develop malignant peripheral nerve sheath tumours (MPNST). However, no population based longitudinal studies have assessed lifetime risk. <b>Methods:</b> NF1 patients with MPNST were ascertained from two sources for our north west England population of 4.1 million in the 13 year period 1984-1996: the North West Regional NF1 Register and review of notes of patients with MPNST in the North West Regional Cancer Registry. <b>Results:</b> Twenty-one NF1 patients developed MPNST, equivalent to an annual incidence of 1.6 per 1000 and a lifetime risk of 8-13%. There were 37 patients with sporadic MPNST. The median age at diagnosis of MPNST in NF1 patients was 26 years, compared to 62 years in patients with sporadic MPNST (p&lt;0.001). In Kaplan-Meier analyses, the five year survival from diagnosis was 21% for NF1 patients with MPNST, compared to 42% for sporadic cases of MPNST (p=0.09). One NF1 patient developed two separate MPNST in the radiation field of a previous optic glioma. <b>Conclusion:</b> The lifetime risk of MPNST in NF1 is much higher than previously estimated and warrants careful surveillance and a low threshold for investigation.