An epidemiological survey of primary tumours of the brain and spinal cord in South East Wales.

This survey is founded on 526 patients who presented with a primary tumour of the brain, spinal cord or their coverings over a seven year period. The patients resided in one of the three counties comprising South East Wales, which has a population of about 1.3 million. Each tumour type is classified according to age, sex and area of residence of the patient. Age and sex adjusted annual incidence rates were calculated for each tumour type. All types of glioma have a higher incidence in males, while meningiomas are twice as common in females. Gliomas are the most commonly occurring tumour with an average annual incidence of 3.6 per 100,000 and a peak incidence for malignant astrocytomas of 7.6 in the 55 to 64 year age group. The low grade astrocytoma is the most common tumour of childhood. Oligodendrogliomas occur most commonly in adults between the ages of 35 and 44 years. In this survey there is an unexplained relatively high incidence of oligodendrogliomas. The majority of primary tumours arose in the brain, but there were 24 tumours of the spinal cord, nerve sheath and meninges. Comment is made on the presence and possible aetiological significance of chemical industries within South East Wales.