Limitations
The retrospective study design was one of our limitations. However, according to our clinical policy, we performed strict follow-up protocol for BC patients. The strict follow-up protocol of the patients might reduce the potential bias associated with the retrospective nature of the study. The relatively low number of patients was another limitation of our study. This might be related with the exclusion criteria of our study population. In order to standardize our study population, patients with incomplete index TUR-B and patients with no muscle tissue at index TUR-B specimen were excluded from the study. Another limitation of our study was the absence of a control group to whom we did not perform re-TUR. However the presence of a control group in high_risk group is an ethical problem for this study design. In our clinical practice, we routinely perform re-TUR to the high_risk NMIBC patients.