a preoperative tumor marking may be used to assist physicians in the removal of tumor tissue by clearly defining the margins of the tumor . an imaging technique , such as mammography , may be employed to visualize the tumor . the visualized tumor may be marked with a polymer , either directly or indirectly . the polymer may be liquid at room temperature and harden at body temperature , making the tumor palpable , but not changing the tumor &# 39 ; s cellular and physical state . the polymer may also include a coloring agent that may aid in visualizing the lesion . this will assist a surgeon during excision by allowing him / her to both feel and see the tumor and remove enough of the tissue surrounding the tumor to greatly reduce the need for a second surgical procedure due to a failure to remove all tumor tissue during an initial surgery .