Childhood cancer rates lowest in the South

A new study by government scientists is the first to document regional differences in the incidence of childhood cancers -- and it shows that the South has the lowest reported rate of all U.S. regions.

But it's still unclear whether fewer children in the South are getting cancer, or whether fewer children there are having their cancers diagnosed.

The study, conducted by the Centers for Disease Control and Prevention in Atlanta, found that childhood cancer in the United States is relatively rare, affecting about 166 out of every one million children. While the Northeast has the highest rate with 179 cases per million children, the South has the lowest rate with 159 cases per million. The rate for the West was 165 per million, while the Midwest's rate was 166 per million.

The researchers looked at children up to age 14 and adolescents between 15 and 19 years of age who were diagnosed with cancer from 2001 to 2003. They found that the cancers occurring most frequently in children are leukemias, cancers of the central nervous system, and lymphomas, which originate in the immune system.

Besides finding differences among regions, the researchers also discovered differences in cancer rates among racial and ethnic groups. For example, the rate of leukemias for Hispanic children at 53.71 per million was significantly higher than that of non-Hispanic children at 41.37 per million. At the same time, the rate of central nervous system cancers was significantly lower for Hispanic children (25 per million) than for non-Hispanic children (30.31 per million). Overall, white, non-Hispanic, adolescent boys have the highest cancer incidence rate.

While the Northeast has the highest childhood cancer incidence rates, it also has the lowest childhood cancer death rate of all the U.S. regions.

Some childhood cancer experts are stumped by the findings, the Associated Press reports:

Dr. Rafael Ducos, a children's cancer physician at Ochsner Medical Center in New Orleans, said the South's low rates were perplexing and might simply reflect under-reporting there and over-reporting in other regions.

"I'm at a loss to explain it," he said.

Scientists say environmental factors including radiation, other pollution, and the age of housing stock might be factors behind the regional disparity in cancer rates. So might access to quality health care. Dr. Lindsay Frazier, a cancer specialist at Children's Hospital Boston and Dana Farber Cancer Institute, told the AP that there might be better access to cancer centers in the Northeast resulting in more diagnoses; that could also explain why children's cancer death rates are lowest there.

The study appears in the June issue of the journal Pediatrics.