[Epidemiological study of primary tumors of the neuraxis in the Rhone-Alps region. Quantitative data on the etiology and geographical distribution of 1670 tumors].

The authors present a retrospective study of 670 histologically verified tumours of the neuraxis collected over 90 months in the Neurological Hospital, Lyons. The main facts concerning histological type, topography of the tumour, date of diagnosis, address, profession, O.B.O. and Rhesus groups, age and sex were codified for feeding into a computer and processed by sophisticated statistical methods. This analysis shows the homogeneity of topographical distribution in the brain of the different types of glioma, the special genetic code of meningiomas (predominance of A and B genes of the A.B.O. group), absence of the same factors for glioblastoma. Sex ratio analysis shows the contrast between definitely masculine tumours--glioblastomas and astrocytomas--and meningiomas and spongioblastomas. Analysis of the "age specific rate" separates tumours prevalent in the young, where incidence is a decreasing function of age (spongioblastoma, medulloblastoma, cerebellar astrocytoma) and tumours prevalent in adults which are mainly meningiomas and glioblastomas whose incidence is an increasing exponential function of age. Epidemiological analysis shows the difference in geographical distribution of glioblastomas and meningiomas. As far as glioblastomas are concerned, it would appear that on to the general rule of constant tumourincidence over the area as a whole, is superimposed another of high incidence in particular districts of the Beaujolais and Maconnais regions. The aetiological implications of these various findings are discussed.