Children who attend daycare or playgroups are about 30 percent less likely to develop the most common type of childhood leukemia, according to University of California, Berkeley researchers who reviewed 14 studies involving nearly 20,000 children, including 6,000 who developed acute lymphoblastic leukemia (ALL).
It's believed that early infections that prime the immune system may help fight off ALL, which accounts for more than 80 percent of leukemia cases among children, and most often occurs between ages 2 to 5, BBC News reported.
"Combining the results from these studies together provided us with more confidence that the protective effect (of social interaction and exposure to infection at a young age) is real," said lead researcher Professor Patricia Buffler.
The study was to be presented at a leukemia conference in London, England.
One expert cautioned against drawing firm conclusions from the study and emphasized there's no solid evidence of an association between infections and leukemia.
"What this study does say is that there is a need for further comprehensive research," Dr. Carole Easton, of the charity CLIC Sargent, told BBC News. "Until we have conclusive evidence then we cannot say for certain what causes childhood leukemia."