Researchers from Baylor University College of Medicine found that children born in countries where hepatitis B is vaccinated had about a 20 percent lower risk of developing certain childhood cancers than children in countries where those vaccines are not routinely administered.
Furthermore, children born in countries that use both polio and hepatitis B vaccines had 30 percent to 40 percent lower odds of developing acute lymphoblastic leukemia, a cancer that affects the white blood cells.
Some common infections are thought to increase children's risk of blood cancers because of the infections' impact on the immune system.
The researchers identified 2,800 cases of childhood cancer diagnosed between 1995 and 2006 among Texas-born children and compared them to those born in areas with lower vaccination rates. They then compared how many children with and without cancer had been born in counties with high vaccination rates.
About 10,000 childhood cancers are diagnosed each year, according to the National Cancer Institute. Most of these are blood and brain and spinal-cord cancers.