**4. Material and Methods**

#### *4.1. Patients and Tumor Material*

In this study, we retrospectively analyzed clinical and histopathological data from 80 patients treated with TURB at the Department of Urology and Pediatric Urology of the University Hospital Erlangen between 2000 and 2015 who were initially diagnosed with stage pT1 NMIBC (Table 6). All patients received a Re-TURB within six to eight weeks after the initial TURB. All patients were treated with a bladder-preserving approach. Tissue from formalin-fixed paraffin embedded (FFPE)

tumor samples from all patients was evaluated for pathological stage according to the 2010 TNM classification [40], and was graded according to the common grading systems [41,42] by two experienced uropathologists (M.E., A.H.). All specimens contained at least 20% tumor cells. All procedures were performed in accordance with the ethical standards established in the 1964 Declaration of Helsinki and its later amendments. All patients treated after 2008 provided informed consent. For samples collected prior to 2008, the Ethics Committee in Erlangen waived the need for informed individual consent. This study was approved by the Ethics Committee of the University Hospital Erlangen (No. 3755; 2008).


**Table 6.** Clinicopathological and survival data.
