The first line of treatment for cancer is, whenever possible, to remove the cancerous tissue from the body. Though often remarkably effective, removing only the cancerous tissue is a challenge for doctors and surgeons. With no intraoperative method to analyze excised tissues, a surgeon typically must rely on preoperative visualizations—ultrasounds, MRIs, and the like—to accurately locate cancerous tissue and then postoperative examinations of the excised tissue to determine whether the cancer