Comparison of Japanese General Rules of Prostatic Cancer and Gleason grading system

Background: We compared the prognostic efficacy between the Japanese Genera l Rules of Prostatic Cancer (JGRPC) and the Gleason grading system (GGS) by applying them to a single set of patients and assessing the survival outco me. Methods: One hundred and seventy-six patients with previously untreated pro state cancer were studied. One experienced Japanese pathologist graded the slides with JGRPC. Another experienced American pathologist graded the same slides with the Gleason grading system. The JGRPC grades were correlated w ith the Gleason scores (GS) grouped into three (GS 2-4, 5-7 and 8-10) or fo ur (GS 2-4, 5-6, 7 and 8-10) tiers. Results: The highest cancer death rates were seen in the higher grade group s in both systems. Comparison of JGRPC grade and three-tiered grouping of t he GS showed identical grades in 81 of 176 cases (46.0%). The overall kappa value of agreement was only 0.151. The 96 cases of JGRPC moderately differ entiated carcinoma group contained two nearly equal-sized groups by the Gle ason grading system, those with GS 5-7 (47 cases) and GS 8-10 (49 cases). T here was a significant difference in survival rate between the GS 5-7 and G S 8-10 groups. No significant differences were noted in the reverse analysi s of survival by JGRPC groups within patients with the same GS three-tiered groups. Similar trends were seen when JGRPC was compared with the four-tie red grouping of the GS. Conclusion: Both JGRPC and the Gleason grading system are useful in estimat ing the prognosis of prostate cancer, but only a mild correlation was found between the two systems. The Gleason grading system may provide more progn ostic information than JGRPC in the moderately differentiated group.