694 DOES TUMOR SIZE INFLUENCE THE ACCURACY OF URETEROSCOPIC BIOPSY FOR UPPER TRACT UROTHELIAL CARCINOMA

INTRODUCTION AND OBJECTIVES: Select low grade tumors of the upper urinary tract can be effectively managed with nephronsparing endoscopic therapy. Unfortunately, some patients that present with low grade disease based on current staging paradigms are upgraded/staged after surgery. We examine clinicopathologic factors associated with accuracy of diagnostic biopsy for upper tract urothelial carcinoma (UTUC). METHODS: Clinicopathologic records of patients diagnosed with UTUC and treated surgically by a single urologist without neoadjuvant systemic therapy were reviewed. Clinical cTx staging was assigned when no degree of invasion was apparent on biopsy and imaging findings. All pathologic specimens were re-reviewed by an experienced genitourinary pathologist (CG) and tumor size was assessed by 4 types of measurement 1) surface area (cm2) 2) index volume (cm3) 3) aggregate volume (cm3) 4) index tumor single dimension (cm). Diagnostic biopsy grade (bG) was compared with pathologic grade (pG) and stage with McNemarAEs test ofagreement. FisherAEs exact or Wilcoxon rank sum was used to determine the association of clinical and pathologic features to changes in grade and stage. RESULTS: We identified 66 patients meeting inclusion criteria. The majority were male (61%) and Caucasian (92%), with mean age of 74.6 years (SD 9.9). Table 1 outlines characteristics of diagnostic biopsies. 17 of 40 patients (43%) were upgraded and 2 of 26 (8%) were downgraded at nephroureterctomy (NU). Overall, bG was significantly different from pG (p 0.006) or stage (p 0.025). The predictive value of low bG for noninvasive disease at NU was 80% and the predictive value of high bG for muscle invasive disease at NU was 62%. Age, sex, clinical stage, multifocality were not associated with change in bG. In cTx patients tumor surface area was significantly associated with higher pT stage (p 0.0492). Patients with low bG found to have advanced stage at NU had a significantly (p 0.049) higher tumor surface area (median 15, 3-211) than those not upstaged (median 8.1, 0.8-27), and were more likely to have an index tumor dimension 3.8cm. CONCLUSIONS: Overall, low bG can predict candidates without invasive disease for nephron sparing therapy in 80% of cases. In cTx patients with low bG, tumor surface area 8.1cm2 and dimension 3.8cm may help select those least likely to be upstaged.