Outcomes of nonmetastatic micropapillary variant upper tract urothelial carcinoma

Purpose: Micropapillary variant upper tract urothelial cancer (MP-UTUC) is a rare malignancy with little known regarding its clinical course and/or optimal treatment. In this case series, we describe patient characteristics, surgical treatment, oncologic outcomes, and response to perioperative chemotherapy. Materials and Methods: We conducted a review to identify patients with MP-UTUC treated at our center between January 1994 and October 2017. Clinicopathologic data was obtained. Descriptive statistics, Kaplan-Meier analysis, Cox proportional hazards, and nearest neighbor matching were used to examine the cohort. Results: Eighteen, (4.3%) of 416 patients were found to have MP-UTUC at our institution over a 23-year period. The majority of patients had ≥pT3 disease at the time of extirpative surgery (13/18, 72%) and one was identified as MP-UTUC prior to surgery. Seven patients received neoadjuvant chemotherapy and six patients received adjuvant chemotherapy. Median overall, cancer specific, and recurrence free survival were 3.29, 3.29, and 1.69 years, respectively for MP-UTUC. There was no survival difference between conventional UTUC and MP-UTUC when matched for age, stage, grade, lymphovascular invasion, and margins (HR 1.18, P = 0.567). No MP-UTUC patients receiving neoadjuvant and adjuvant chemotherapy had apparent pathologic down staging, and of those receiving adjuvant chemotherapy two-thirds died of disease within 2 years. Conclusions: MP-UTUC is a rare, and in most cases aggressive malignancy that commonly presents as locally advanced disease. In this case series, MP-UTUC does not appear to respond to perioperative chemotherapy as neoadjuvant and adjuvant chemotherapy did not result in apparent pathologic down staging and the majority of those receiving adjuvant chemotherapy died from MP-UTUC.