 Today, tumor remaining in a patient after therapy with curative intenteg. surgical resection for cure is categorized by a system known as R classification. That is shown: RX: presence of residual tumor can not be assessed; R0: no residual tumor; R1: microscopic residual tumor; R2: macroscopic residual tumor; The residue with the application of R classification not only refers to both residual tumor at the margin of surgical excision but also residue in distant metastasis. The higher R classification is, the worse the prognosis becomes. 