Malignant peripheral nerve sheath tumours in NF1: improved survival in women and in recent years

Malignant peripheral nerve sheath tumours (MPNST) are the main soft tissue malignancy associated with neurofibromatosis 1. These uncommon tumours are known to occur at high frequency and lead to poor survival. Our aim was to determine risk of MPNST in NF1 patients, and survival rates.

The incidence of MPNST in NF1 was identified through the NF1 genetic register and The North West Cancer Intelligence Service (NWCIS). Data were used to generate incidence and survival curves. Strict regional boundaries were adhered to avoid ascertainment bias. Kaplan-Meier curves were used to determine five and ten-year survival.

Of the 1059 NF1 patients 52 developed MPNST (30 cases in females and 22 in males), 43 cases were resident within the strict regional boundary. The risk of MPNST was 10.2% in males and 12.7% in females by age 70 years (p=0.9), with a statistically better survival in females than males (5 and 10 year survival 46% and 41.5% versus 22% and 8.2%; p=0.05). Survival was also significantly improved for patients diagnosed in the last 14 years compared to the previous 13-year period (p=0.03).

With fifteen strict regional MPNSTs in the fourteen years since our previous population study an annual incidence of above 1 per 1000 NF1 patients has now been maintained over a 27-year period. No significant increase in risk of MPNST in females compared to males was found, though the difference in survival is intriguing. Male survival is particularly poor with <10% alive at 10 years.