Tumors of the Nervous System

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. 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. 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<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. The lifetime risk of MPNST in NF1 is much higher than previously estimated and warrants careful surveillance and a low threshold for investigation.

The rates of survival, tumor recurrence, and tumor progression were analyzed in 225 patients with meningioma who underwent surgery as the only treatment modality between 1962 and 1980. Patients were considered to have a recurrence if their studies verified a mass effect in spite of a complete surgical removal, whereas they were defined as having progression if, after a subtotal excision, there was clear radiological documentation of an increase in the size of their tumor. There were 168 females and 57 males (a ratio of 2.9:1), with a peak incidence of tumor occurrence in the fifth (23%), sixth (29%), and seventh (23%) decades of life. Anatomical locations were the convexity (21%), parasagittal area (17%), sphenoid ridge (16%), posterior fossa (14%), parasellar region (12%), olfactory groove (10%), spine (8%), and orbit (2%). The absolute 5-, 10-, and 15-year survival rates were 83%, 77%, and 69%, respectively. Following a total resection, the recurrence-free rate at 5, 10, and 15 years was 93%, 80%, and 68%, respectively, at all sites. In contrast, after a subtotal resection, the progression-free rate was only 63%, 45%, and 9% during the same period (p less than 0.0001). The probability of having a second operation following a total excision after 5, 10, and 15 years was 6%, 15%, and 20%, whereas after a subtotal excision the probability was 25%, 44%, and 84%, respectively (p less than 0.0001). Tumor sites associated with a high percentage of total excisions had a low recurrence/progression rate. For example, 96% of convexity meningiomas were removed in toto, and the recurrence/progression rate at 5 years was only 3%. Parasellar meningiomas, with a 57% total excision rate, had a 5-year probability of recurrence/progression of 19%. Only 28% of sphenoid ridge meningiomas a second resection, the probability of a third operation at 5 and 10 years was 42% and 56%, respectively. There was no difference in the recurrence/progression rates according to the patients' age or sex, or the duration of symptoms. Implications for the potential role of adjunctive medical therapy or radiation therapy for meningiomas are discussed.