My stepson Roberto Saenz was heading to junior prom in 2009 when his brain tumor symptoms began. As he rode in the limo, he started to have a severe headache and began vomiting. His mother, Debbie, took him to the children’s hospital in Corpus Christi, Texas, where doctors diagnosed him with a severe sinus infection.

Growing up, Roberto had had a history of frequent headaches, but they were becoming more painful and medication...