Family Size Tied to Brain Tumors, Study Suggests

Here is an interesting piece from the NYTimes Science section. You cannot jump to a conclusion from one study. But, there are important things to look for in research. Where was it published? Neurology...yes, not too shabby. Next, how big a sample size? 13,613 ....very respectable. I'll keep an eye out to see if any further work is published on this topic. In the meantime, I really like the last line that states, "This is a preliminary study and we are speculating that this is one of the possible interpretations of the association we found." That's a good way of saying that it looks interesting so far, stay tuned.

December 26, 2006 New York Times By NICHOLAS BAKALAR

The more siblings you have, the more likely you may be to develop a brain tumor, a new study reports. Researchers writing in the Dec. 12 issue of Neurology reviewed the records of 13,613 Swedish brain cancer patients and found that those with four or more siblings were almost twice as likely to develop a brain tumor as those with no siblings at all. The risk increased with the number of younger siblings and in children under 15, where it increased nearly four-fold for one type of tumor.

According to background information in the paper, the established risk factors for nervous system tumors are high doses of ionizing radiation, family history and some rare genetic syndromes. But these factors explain only a minority of brain cancers.
The authors suggest that infection may also be involved. Having large numbers of siblings increases the overall pool of infections, and children coming into close contact with one another share exposures to many infectious agents.

The associations persisted even after controlling for sex, age at diagnosis, parental history of cancer and socioeconomic status. The authors caution, however, that any conclusions about an infectious cause remain speculative because molecular studies have not identified a specific germ.

Dr. Andrea Altieri, the lead author, said the study did not prove that brain tumors were caused by infection or that living in a large family was in any way dangerous. “We are not suggesting that infection causes brain tumors,” said Dr. Altieri, an epidemiologist at the German Cancer Research Center in Heidelberg. “This is a preliminary study, and we are speculating that this is one of the possible interpretations of the association we found.”