Long-term follow-up of TaG1 non-muscle-invasive bladder cancer

To retrospectively assess the long-term outcome of patients initially diagnosed with TaG1 non-muscle-invasive bladder cancer (NMIBC) with no immediate postoperative instillation of intravesical chemotherapy and evaluate the reproducibility of the European Organization for Research and Treatment of Cancer (EORTC) scoring system for predicting bladder cancer outcome.

A retrospective analysis of 481 consecutive cases of initially diagnosed TaG1 NMIBC according to the 1973 World Health Organization classification between 1995 and 2008 in a single institution was performed. Time to first recurrence, time to progression to T1 or G3 bladder cancer, and time to progression to muscle-invasive bladder cancer were studied. Time to event distributions was estimated by means of cumulative incidence functions to accurately take into account the patients who died (competing risk) before recurrence or progression. The Harrell c statistic calculation was used for our study's data results as well the original data from EORTC to compare the predictive power of a survival model.

The median follow-up was 88 months (interquartile range: 51-135 mo). The 10-year recurrence-free, T1 or G3 NMIBC progression-free, and muscle-invasive bladder cancer progression-free survival rates were 64.2%, 96.6%, and 97%, respectively. In multivariate analysis, tumor size and number of lesions were prognostic variables of the risk of recurrence. In our study and EORTC data sets, the Harrell c values obtained were c = 0.85 (95% CI: [0.75, 0.93]) and c = 0.85 (95% CI: [0.75, 0.93]), respectively.

Our study reports a detailed and extensive outcome of TaG1 NMIBC treated by TURB with no immediate postoperative intravesical instillation of chemotherapy. Our results suggest that the EORTC is a useful external validation scoring system for predicting bladder cancer outcome.