Clinicopathological Analysis of Patients with Non-muscle-invasive Bladder Cancer: Prognostic Value and Clinical Reliability of the 2004 WHO Classification System

The aim of this study was to clarify the prognostic value and clinical reliability of the 2004 World Health Organization classification system of non-muscle-invasive bladder cancer.Between January 1995 and November 2010, 153 patients were diagnosed with non-muscle-invasive bladder cancer. We used a substage system that discerns T1-microinvasive (T1m, 42 patients) and T1-extensive-invasive (T1e, 37 patients) cancers.There were 2 (1.3%), 89 (58.2%) and 62 (40.5%) cases of Grade 1-3 urothelial carcinoma, respectively, on the basis of the 1973 World Health Organization classification system. Of these, 37 (24.2%) and 116 (75.8%) were graded as low and high on the basis of the 2004 World Health Organization classification system. All of the cases with progression (15 patients) were diagnosed as high grade at the time of primary transurethral resection of the bladder tumor. Based on the Kaplan-Meier analysis, the 2004 World Health Organization classification system accurately predicted tumor recurrence (P = 0.029) and progression (P = 0.031). The 5-year recurrence-free survival rates in patients with low-grade and high-grade tumors were 68.7 and 47.1%, and the 5-year progression-free survival rates were 100 and 89.0%, respectively. In the high-grade T1 cases, the substage (T1m or T1e) was a significant predictor of tumor recurrence (P = 0.001) and progression (P = 0.020).The 2004 World Health Organization classification system accurately predicts the risk of recurrence in primary non-muscle-invasive bladder cancer cases and has the same accuracy when predicting the risk of progression as the 1973 World Health Organization classification. Furthermore, the substaging system for high-grade T1 tumors is useful in predicting both recurrence and progression.