1. A medical image processing device for extracting from a medical image, and displaying, lesion candidate regions on a surface of an organ, the medical image processing device comprising: a first extracting unit that makes a first evaluation of a curved surface form of the organ by using an initial parameter, and extracts first lesion candidate regions from volume image data based on the first evaluation; a second extracting unit that makes a second evaluation of a curved surface form of the organ by using a parameter reset based on a region size of each of the first lesion candidate regions, and re-extracts second lesion candidate regions from volume image data based on the second evaluation; and a display unit that superimposes and displays the second lesion candidate regions extracted by the second extracting unit on a second medical image.