NEW YORK: Children who have had certain vaccines may be less likely to develop childhood cancer, especially one type of leukemia, according to a US study. The findings, published in The Journal of Pediatrics, showed that children born in areas where most children had been vaccinated for hepatitis B had about 20 percent lower odds of all types of childhood cancer than those born in areas where fewer were vaccinated. In particular, those born in areas with high use both of polio vaccine and a vaccine series that included hepatitis B and polio, among other diseases, had 30 percent to 40 percent lower odds of getting acute lymphoblastic leukemia – a type of leukemia that is most common in childhood. Michael Scheurer, from the Baylor College of Medicine in Houston, Texas, and one of the study authors, warned that despite the apparent relationship, which should become clearer with future research, it's not a situation of “get your kids vaccinated and they won't get cancer.” One theory is that some common infections may increase a child's risk of leukemia because of the effect they have on the developing immune system. Vaccinations, theoretically, should then cut down on that cancer risk – unless the vaccine itself closely enough mimics a natural infection. For each child diagnosed with cancer, the researchers found four others of the same age and gender who had not. Then, they compared how many of the children with or without cancer had been born in counties with high vaccination rates. According to Scheurer, the strongest finding was a decreased risk of leukemia in areas with high vaccination rates for hepatitis B and polio – which is also where most of the previous childhood cancer research has shown a benefit for vaccination.
