Researchers at Penn Medicine are exploring a new strategy to prevent breast cancer from returning by targeting so-called “sleeper” cancer cells, according to Dr. Angela DeMichele. The goal here is to prevent women from developing metastatic breast cancer, which remains incurable. If those sleeper cells are detected, what options are available for a patient and their care team? That’s a very unique state for a cancer cell, because cancer cells typically like to divide. All of our treatments so far target dividing cancer cells.