Facing incurable breast cancer at age 55, MaryAnne DiCanto put her faith in “precision medicine” — in which doctors try to match patients with drugs that target the genetic mutations in their tumors. She underwent repeated biopsies to identify therapies that might help.

“She believed in it wholeheartedly,” said her husband, Scott Primiano of Amityville, N.Y.

Around this point in the typical news report, readers would learn how Ms. DiCanto, mother to a blended family of five, took a chance on an experimental drug that no one expected to work.

She would be the scrappy protagonist who beat the odds — allowing us to celebrate the triumph of modern science and worry a bit less about our own mortality.

But there’s a problem with talking about precision medicine for cancer this way: It misleads the public.