MP58-14 LIMITS OF TRANSURETHRAL RESECTION IN DETECTING UNCOMMON HISTOLOGICAL VARIANTS WITHIN BULKY BLADDER TUMORS IN REAL-LIFE CLINICAL PRACTICE

render accurate pre-operative staging paramount. Incidental indeterminate pulmonary nodules (IPNs) are a common pre-operative finding in clinical practice, thus representing a significant management challenge since metastatic patients are unlikely to benefit from extirpation. Thus, we sought to evaluate the natural history of IPNs in a large institutional cohort that underwent RC. METHODS: We reviewed our institutional database for patients who underwent RC from 2000-2014 for urothelial carcinoma (UCC) of the bladder & had 1 identifiable pulmonary lesion on preoperative staging imaging measuring <2cm in any axis. Patients who were M1 at surgery or had non urothelial histology were excluded. Cumulative incidence of any lung metastasis was estimated, adjusting for competing risk of death; overall survival (OS) was estimating using Kaplan Meier methods. We sought to determine the natural history of these pulmonary lesions and evaluated predictors of metastatic etiology. RESULTS: During the study period, 681 RC were performed at our institution. Of which, 73 patients with an identifiable preoperative IPN met inclusion criteria & underwent RC. In this subset, 23% were female, 22% were active smokers & 55% former smokers. The median age at surgery was 70 yrs (range 43-88). 51% received neoadjuvant chemotherapy & 62% of RC were performed using the traditional open approach (vs 38% robotically). Final pathologic staging included 16% pT0N0Mx, 19% pTa/Tis/T1N0Mx, 43% pT2-4N0Mx, & 22% pTanyN+Mx. Median IPN size was 0.7 0.3cm. At median follow up of 23.5 months, the IPNs in 92% (67/73) of patients were clinically benign, with metastatic urothelial cancer confirmed in only 5 patients, & a primary lung malignancy diagnosed in 1 patient. In the IPN cohort, lung metastasis at non-IPN sites were detected in 2 additional patients. Cumulative incidence of any lung metastasis at 12, 24 & 36 months was 5.9% (95%CI 1.9-13.3%), 7.6% (95%CI 2.8-15.7%), & 10.3% (95%CI 3.9-20.2%), respectively. OS at 12, 24 & 36 months was 75.3% (95%CI 62.3-83.9%), 65.8% (95%CI 53-1-75.9%), & 54.0% (95%CI 39.766.2%), respectively. CONCLUSIONS: The majority of IPNs in patients who proceeded to RC for UCC of the bladder were stable upon follow-up & rarely represented malignancy. Patients with IPNs have OS consistent with previously published literature. As such, in appropriately screened UCC patients, IPNs should not be a barrier to proceeding with extirpative surgical therapy.