1. A Computer Aided Diagnosis (CAD) apparatus comprising: a memory configured to store instructions therein; and at least one processor, upon execution of the instructions, configured to: detect at least one region of interest (ROI) on a medical image; detect, based on eye movement of a user, a gaze area on the medical image on which the at least one ROI on the medical image is detected, the gaze area being an area at which the user gazes for a period of time; detect at least one ROI on the gaze area; and modify a first detection result of the at least one ROI on the medical image, based on a second detection result of the at least ROI on the gaze area.