Cancer surgery does not end after removing a tumor. Within the area of flesh surrounding the tumor, malignant tissue may be hiding among healthy tissue. Surgeons then face a challenging decision: judging which parts of this flesh need to be taken out, and which parts are safe to leave alone. If they are unable to catch everything, the cancer could grow back. A promising new surgical probe, which instantly lets surgeons tell apart healthy from cancerous cells by how they each scatter light, may help keep patients from returning to the operating room. Read more at NOVA Next.