Oncological predictive value of the 2004 World Health Organisation grading classification in primary T1 non-muscle-invasive bladder cancer. A step forward or back?

OBJECTIVE: To compare the clinical reliability of the 1973 and 2004 World Health Organisation (WHO) classification systems in pT1 bladder cancer. PATIENTS AND METHODS: We retrospectively evaluated 291 consecutive patients who had pT1 high grade bladder cancer between 2004 and 2011. All tumours were simultaneously evaluated by a single uro-pathologist as high grade and G2 or G3. All patients underwent a second transurethral resection (TUR) and those confirmed with non-muscle-invasive bladder cancer at second TUR received bacille Calmette-Guérin. Follow-up included urine cytology and cystoscopy 3 months after second TUR and then every 6 months for 5 years. Univariate and multivariate analysis to determine recurrence-free survival (RFS) and progression-free survival (PFS) rates were performed using the Kaplan­Meier method with the log-rank test. RESULTS: G2 tumours were found in 124 (46.6%) and G3 in 142 (53.4%) patients. The mean (median; range) follow-up period was 31.1 (19; 1­93) months. The 5-year RFS rate was 39.1% for the overall high grade population, and 49.1 and 31.8% for G2 and G3 subgroups, respectively. The 5-year PFS was 82% for the overall high grade population and 89 and 73% for G2 and G3 subgroups, respectively. RFS (P < 0.002) and PFS (P < 0.001) rates were significantly different between the G2 and G3 subgroups. In multivariate analysis, only the grade assessed according to the 1973 WHO significantly correlated with both RFS (P = 0.003) and PFS (P < 0.001). CONCLUSION: The results suggest that the 1973 WHO classification system has higher prognostic reliability for patients with T1 disease. If confirmed, these findings should be carefully taken into account when making treatment decisions for patients with T1 bladder cancer.