Narrator: This is Science Today. Leukemia is a heterogeneous disease – meaning, there are several different subtypes. The two major subtypes are acute myeloblastic leukemia and acute lymphoblastic leukemia, or ALL. Marilyn Kwan, a postdoctoral researcher in epidemiology at the University of California, Berkeley, says ALL is the most common childhood leukemia subtype.

Kwan: It accounts for probably seventy-five percent of all leukemia cases and it actually has the best prognosis nowadays. I think there's a survival rate of eighty percent in young kids. So it's very encouraging – we've come a long way since 1960 for treatment of childhood leukemia.

Narrator: Kwan led a recent review of studies that found that children who are breastfed have a lower risk of developing childhood leukemia.

Kwan: This study is different because it's a comprehensive, systematic literature review of all the studies that have been conducted on childhood leukemia and breastfeeding to date.

Narrator: For Science Today, I'm Larissa Branin.