In contrast to the majority of other genetic cancer syndromes reviewed in this book, neurofibromatosis 1 (NF1) and neurofibromatosis 2 (NF2) do not result in cancer developing in the majority of affected individuals. In NF1, the tumours that develop in the majority of patients are benign cutaneous neurofibromas. People with NF1 have a small but significant risk of specific cancers developing; these include malignant peripheral nerve tumours (MPNST), rhabdomyosarcomas, atypical forms of childhood leukaemia and astrocytomas. In NF2, the tumours are nearly always histologically benign and include vestibular Schwannomas (also called acoustic neuromas), meningiomas, Schwannomas and spinal ependymomas. Although these tumours are not malignant, curative surgery is often difficult, and NF2 is associated with significant disease-related morbidity and mortality.