1. A Computer Aided Diagnosis (CAD) apparatus comprising: a memory configured to store instructions; at least one processor, upon executing the stored instructions, configured to: detect a Region of Interest (ROI) from a plurality of image frames, create at least one group of image frames based on a result of the detection, wherein the at least one group comprises successive image frames in which the ROI is detected, from among the plurality of image frames, extract a feature value from at least one of a contour of the ROI comprised in the successive image frames, an area adjacent to the contour, or pixels inside the contour, classify the ROI comprised in each of the successive image frames belonging to the at least one group by comparing the extracted feature value with a pre-stored diagnostic model, combine classification results for the successive image frames belonging to each group from the at least one group, and calculate a group result for the each group based on a result of the combination; and a display configured to display the group result on a screen.