A family member was diagnosed with ALL this week. That family member also spent 5 weeks in NICU because they were very premature. The oncologist noted at time

A family member was diagnosed with ALL this week. That family member also spent 5 weeks in NICU because they were very premature. The oncologist noted at time of the ALL diagnosis that NICU babies had a higher incidence rate of ALL later in life. Perhaps here is the causation for that anomaly - reduced very-early exposure to bad microbes in the sterile NICU environment results in an underdeveloped immune system less able to resist genetic mutations leading to ALL. Perhaps it's something about very early exposure for infants, as at least in the case of my family member, the parents were _not_ hypoallergenic and the child began daycare at a pretty early age (and thus subject to all kinds of nasty nasty germs)