Autism is a pervasive developmental disorder characterized by severe impairments in social skills, language and communication, as well as behavioral disturbances. There is growing public awareness of autism because rates of this disorder are thought to be rising [1]. The etiology of autism is still unknown and clues as to its cause are urgently needed. Check the end of this report for a link to download this open access article.
Introduction (continued)
Previous studies have reported that children with autism possess a higher number of genetic aberrations, including higher levels of chromosomal rearrangements [2] and copy number variations [3,4,5,6,7]. These studies raise the possibility that there may be correlations to cancer, a disease in which chromosomal aberrations are known to play a role. Here, researchers report a study in which the incidence of cancer is compared to the prevalence of autism.
Method
To determine if significant correlations exist between the prevalence of autism and the incidence of cancer, researchers obtained and analyzed state-wide data reported by age and gender throughout the United States. Autism data were obtained from the U.S. Department of Education via the Individuals with Disabilities Education Act (IDEA) (2000–2007, reported annually by age group) and cancer incidence data were obtained from the Centers for Disease Control and Prevention (CDC) (1999–2005). IDEA data were further subdivided depending on the method used to diagnose autism (DSM IV or the Code of Federal Regulations, using strict or expanded criteria).
Results
High correlations were found between autism rates and the incidence of in situ breast cancer using data from states that adhere strictly to the Code of Federal Regulations for diagnosing autism. By contrast, few significant correlations were observed between autism prevalence and the incidence of 23 other female and 22 male cancers. When a less conservative statistical method was applied (Simes’ procedure), correlations between autism and uterine cancer also emerged as consistently significant.
Conclusion
In conclusion, by using conservative statistical methods and a limited set of autism data from states using a uniform code of diagnosis, nominal statistical significance was observed in a few instances, notably for breast cancer and uterine cancer. In practice, it is not known whether the diagnosis of autism is truly uniform in individual school districts. Consequently, the results should be interpreted with caution, even if the p-values appear to be selective for these cancers and highly significant, as is the case here.
Nonetheless, it is of interest that the cumulative exposure to estrogen from endogenous and external sources is an established risk factor for both breast [20] and uterine [21] cancer, the two cancers that appear to be most consistently correlated with autism. Some analyses suggest that mothers are carriers of mutations that predispose children to autism [22], and there is literature implicating germline mutations in autism [23,24]. In this context, it is suggested that investigation of biomedical mechanisms to account for these epidemiological findings is warranted.
Citation/Download
Material adapted by CFisher from:
Kao H-T, Buka SL, Kelsey KT, Gruber DF, & Porton B (2010). The Correlation between Rates of Cancer and Autism: An Exploratory Ecological Investigation. PLoS ONE 5(2): e9372. doi:10.1371/journal.pone.0009372
References
Please see the freely available article for the extensive reference list. Numbered references in this current article match the references in the original article.
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