Etiology and Pathogenesis > Infection

Abstract

Association between number of siblings and nervous system tumors suggests an infectious etiology

From the Division of Molecular Genetic Epidemiology (A.A., F.C., J.L.B., K.H.), German Cancer Research Centre (DKFZ), Heidelberg, Germany; and Center for Family Medicine (K.H.), Karolinska Institute, Huddinge, Sweden. -- Address correspondence and reprint requests to Dr. Andrea Altieri, Deutsches Krebsforschungszentrum (DKFZ), Division of Molecular Genetic Epidemiology, Im Neuenheimer Feld 580, D-69120 Heidelberg, Germany; e-mail: altieri73@gmail.com. -- Received April 5, 2006. Accepted in final form August 17, 2006.

Methods. The Swedish Family-Cancer Database comprises 13,613 diagnoses of nervous system tumors with histopathologic information. 
We analyzed the data using Poisson regression models taking into account potential confounding effects of age, birth cohort, socioeconomic status, and family history of cancer.

Results. The rate ratios (RR) for having four or more siblings vs none were significantly increased for hemangioblastoma (RR = 1.68), childhood neuroblastoma (RR = 2.01), and ependymoma (RR = 1.83, p trend < 0.01). 
For age at diagnosis ≤15 years, the RRs for individuals with three or more younger siblings compared to none were 1.34 for astrocytoma, 2.30 for medulloblastoma, 2.61 for ependymoma, 3.71 for meningioma, and 2.13 for neuroblastoma, with significant trends in risk. 
Non-significant decreased risks were found between the number of older siblings and nervous system tumors.

Conclusions. We provide the first reliable quantification of the effects of number of siblings on the risk of nervous system tumors. 
Sibship size and number of younger siblings correlate with the incidence of childhood nervous system tumors, suggesting a role of infectious agents in the etiology of the disease.