Newborn head size linked to cancer risk

Healthy babies born with larger-than-average heads may face an increased risk of childhood brain cancer, a study suggests.

Head circumference reflects brain size, so a large head circumference may indicate abnormal growth in the brain. Norwegian researchers analyzed 1.1 million records of births between 1978 and 1998, excluding babies born with very small or very large heads that would indicate other medical problems. The scientists also ruled out babies born extremely premature, overdue, underweight, or overweight.

By matching the head-size data with information from the Norwegian cancer registry, the researchers assessed how many babies born with a given head size went on to develop brain cancer.

The overall risk of brain cancer was small, says study coauthor Sven Ove Samuelsen of the Norwegian Institute of Public Health in Oslo. Only 453 children in the study developed the disease.

But babies born with a head circumference of 39 centimeters or more were four times as likely to develop brain cancer as were babies born with average-size, 35-cm heads, the researchers report in the January Lancet Oncology. Babies born with 38-cm heads had a risk of brain cancer nearly double that of the average group.

The findings suggest that brain cancer, or conditions conducive to it, originate in the womb, the scientists note. The cancer could arise from immature, cancer-prone cells under the influence of growth-promoting proteins in the brain, the researchers speculate, or from exposure to radiation or infections. In any case, the risk appears to be site-specific: Head size wasn’t associated with development of leukemia or other cancers.