Cindy Stueber was supposed to be helping her daughter, Shelby, look at wedding dresses and elegant up-dos. Instead, she was making plans to help Shelby cut her hair, which, once long and thick, was now thinning and sparse from medulloblastoma treatment.

There would be time for those up-dos later, Cindy reminded herself. Shelby’s brain tumor had been removed after her medulloblastoma diagnosis a month earlier, and the brain tumor...