SUO 2017: Papillary Urothelial Neoplasia of Low Malignant Potential (PUNLMP) Recurrence Rates

Washington, DC (UroToday.com) Dr. Neal Shore and colleagues presented their research on papillary urothelial neoplasia of low malignant potential (PUNLMP) recurrence rates. As of 2004, the World Health Organization (WHO) has endorsed PUNLMP as a uropathologic entity, stratifying WHO 1973 Grade 1, 2, and 3 tumors as PUNLMP, low grade, and high-grade disease, respectively. Some pathologists report a 1:1 exchange as G1: PUNLMP, G2: low-grade, G3: high-grade, whereas others propose a sliding comparison designating G1 to either PUNLMP or low grade, and G2 to either low-grade or high-grade tumors. Despite PUNLMP’s seemingly innocuous clinical course, the authors note that many are still uncertain regarding its low risk of recurrence. The objective of this study was to review data from two phase III non-muscle invasive bladder cancer (NMIBC) trials with prospective central pathology to report PUNLMP incidence and 2-year recurrence rates and to assess the benefit of a single dose of an intravesical therapy.

Between 2007 and 2011, 1,614 patients with presumed TaG1-2 NMIBC were randomized either to placebo or apaziquone post-transurethral resection (TUR). There were 1,146 patients with TaG1-2 disease. WHO 2004 grading was also performed with 700 patients having both grades recorded. Study assessment was based on central review by Bostwick Laboratories and cystoscopic follow up occurred every 3 months for 2 years. In the cohort of TaG1-2 patients, central review diagnosed PUNLMP more often than low-grade disease (519:181). Local and central 2004 grading were compared in 312 patients for concurrence. PUNLMP by central review was diagnosed locally as PUNLMP in 51 patients, low-grade in 179, and high-grade in 11 patients. The 2-year recurrence rate for patients with PUNLMP was 45% and 53% for patients with low-grade tumors. Both PUNLMP (OR 0.71) and low-grade tumors (OR 0.69) had improved 2-year recurrence rates after a single dose of apaziquone. 

In summary, the incidence of PUNLMP increases with central pathology review. Furthermore, based on post-hoc analysis of prospective trial data the 2-year recurrence rate for PUNLMP is 45%, which improves with of a single intravesical dose apaziquone. The authors conclude that further research on the PUNLMP diagnosis, its clinical significance and response to intravesical therapy is warranted.

Presented by: Neal Shore, Carolina Urologic Research Center, Myrtle Beach, SC
Co-Authors: Anne Simoneau, Larry Karsh, David Bostwick, Mark Soloway, Sharon Leu, and Gajanan Bhat

 Written By: Zachary Klaassen, MD, Society of Urologic Oncology Fellow, University of Toronto, Princess Margaret Cancer Centre @zklaassen_md at the 18th Annual Meeting of the Society of Urologic Oncology, November 20-December 1, 2017 – Washington, DC
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