Low incidence of SV40-like sequences in ependymal tumours

Between 1955 and 1963, millions of children and adults were exposed to SV40 -contaminated poliovirus vaccines. The oncogenic potential of this polyomav irus was revealed when intracerebral inoculation of SV40 into newborn hamst ers resulted in the development of ependymomas and choroid plexus papilloma s. Subsequently, SV40-like sequences were repeatedly detected in human epen dymomas with broadly ranging incidence rates of 7-90%. Most epidemiological studies, however, have not described an increased occurrence of ependymoma s. To gain more data on this controversial issue, this study examined 62 ar chived ependymal tumours from 31 children and 31 adults who underwent surge ry between 1990 and 1999. Only three (5%) of the tumours - including 24 cla ssical, 20 anaplastic, and 12 myxopapillary ependymomas; one subependymoma; and five ependymoblastomas - revealed subgenomic SV40 sequences. None of t he ependymomas in patients born between 1920 and 1960 demonstrated SV40-lik e sequences. The positive tumours represent 7% of grade II and III ependymo mas (two paediatric and one adult tumour). DNA sequencing of the PCR produc t revealed identical sequences of SV40 in the positive ependymal tumours. C ompared with the results from other countries, this incidence rate is relat ively low. Therefore, it seems likely that significant differences between individual countries exist regarding the prevalence of SV40-positive ependy momas. These differences may reflect different degrees of exposure to SV40- contaminated polio vaccine. Copyright (C) 2001 John Wiley & Sons, Ltd.