Introduction

One of the major challenges regarding upper tract urothelial carcinoma (UTUC) is to identify patients who can safely be managed by kidney-sparing surgery (KSS). European Association of Urology (EAU) Guidelines proposed criteria for pre-treatment risk stratification includes a tumor diameter >1cm as exclusion criteria for KSS. Our aim was to evaluate the performance of different tumor diameters for identifying advanced pathologic stage after RNU and to assess its prognostic value on survival.

Methods

A multi-institutional retrospective study was conducted that included 800 patients undergoing radical nephroureterectomy (RNU) for non-metastatic UTUC between 1988 and 2016. Tumor sizes were pathologically assessed and categorized into four groups: ≤1, 1.1-2, 2.1-3, >3 cm. We performed logistic regression analyses to compare different diameter thresholds in predicting advanced pathologic stage. Kaplan-Meier analyses with log rank test for comparison was used for the estimation of survival outcomes.

Results

Overall, 31 (3.9%) patients had a tumor size ≤1cm, 107 (13.4%) 1.1-2cm, 175 (21.9%) 2.1-3cm and 487 (60.9%) >3cm. In preoperative predictive models, that adjusted for the effects of clinicopathologic features, tumor diameters >2cm versus ≤2cm (OR 1.90, p=0.011) and >3cm versus ≤3 (OR 1.71, p=0.003), were both independently associated with advanced stage (≥pT2). The addition of tumor size improved the accuracy of the model from 59 to 61 %. Previous bladder cancer (p=0.011) and preoperative hydronephrosis (p=0.015) were also associated with ≥pT2 disease. Tumor sizes >2cm or ≤2cm predicted muscle-invasion (≥pT2) with 57% positive predictive value (PPV) and 59% negative predictive value (NPV), respectively. With a threshold of 3cm the PPV was 59% and NPV 54%. Kaplan-Meier curves did not show a prognostic impact of tumor size on recurrence-free and cancer-specific survival after RNU.

Conclusions

Tumor size of 2cm seems to best identify patients who likely harbor muscle-invasive tumor stage. This puts the current risk stratification of EAU Guidelines based on 1cm into question. Our study is limited by the small sample size of ≤1cm tumors and its design (RNU cohort, retrospective, multi-institutional). Therefore, this area needs further research to better identify the optimal criteria for KSS.

Funding

none