Low Grade Micropapillary Urothelial Carcinoma, Does It Exist? - Analysis of Management and Outcomes from the Surveillance, Epidemiology and End Results (SEER) Database

Abstract

Objective: To elucidate the oncologic behavior of Micropapillary Urothelial Bladder Carcinoma (MPBC), a rare aggressive variant histology.Methods: All MPBC patients in SEER 17 database were compared with those with traditional urothelial carcinoma (UC). Kaplan-Meier curves were used to determine OS and CSS. A Cox proportional hazards model (CPH) was constructed to test the effect of covariates on outcomes.Results: From 2001-2008, 120 MPBC patients were identified, 0.1% of all bladder cancer. MPBC presented with more high grade (86.1% vs. 38.7%, p<0.0001) and more high stage disease (40.8% NMI vs. 90.4% NMI, p < 0.0001) than UC. Low grade (LG) NMI MPBC had worse OS and CSS compared to LG UC (p=0.0037, p<0.0001 respectively), and did no better than high grade (HG) NMI MPBC. No difference was detected between HG NMI MPBC and HG NMI UC pts. A CPH model controlling for stage, grade, treatment, age, race, and sex detected no significant survival difference in MPBC vs. UC (HR 1.04, p=0.7966). For NMI MPBC (n=49), only 4 patients underwent definitive therapy, of whom none died of disease. However, in those not receiving definitive therapy (n=45), 7 cancer specific deaths occurred (15.6%).Conclusion: Controlling for stage and grade, no survival difference could be detected between MPBC and UC. Low grade NMI MPBC behaved similarly to both high grade MPBC and high grade UC. We propose that all MPBC (regardless of grade) be managed as high grade disease, and that strong consideration for definitive therapy should be given in all cases.

Clinical Outcomes of cT1 Micropapillary Bladder Cancer

“…8 NMI-MPBC represents a potentially treatable form of the disease and may warrant a more aggressive management strategy. In 2006, we first advocated early cystectomy for NMI-MPBC, 9 others have suggested that intravesical BCG therapy may be appropriate as primary treatment.…”

Nonurothelial Bladder Cancer and Rare Variant Histologies

“…After controlling for TNM staging, no difference in survival between MPBC and conventional UC was identified except among patients with NMI micropapillary disease, where worse survival outcomes were reported. 9 Other authors have presented conflicting views on NMI MPBC, suggesting that intravesical BCG might be an appropriate therapy. In a recent publication from Memorial Sloan Kettering, equivalent survival outcomes between intravesical BCG and upfront radical cystectomy were reported in a 36 patient cohort with 3 years of follow-up.…”

“…39 The majority of studies consistently show that muscle-invasive MPBC is associated with high rates of locally advanced and distant disease and is associated with poor overall survival. 7,9,[36][37][38]40 Early studies even showed that small amounts of micropapillary component within the tumor was clinically significant with greater than 10% MPBC being associated with worse clinical outcomes. 26,40 The largest single institution series to date from MD Anderson Cancer Center (n 5 100) demonstrated that the overall prognosis of MPBC was poor in this cohort with 5-and 10-year overall survival rates of 54% and 27%, respectively, 23 despite a relatively high proportion of NMI MPBC disease at presentation (44%).…”

“…1 However, since that time, multiple studies have been published showing variant histology present within non-muscleinvasive (NMI) tumors. [6][7][8][9][10][11][12] This is likely a reflection of increased awareness and recognition within the scientific community. In fact, in a large registry with more than 28,000 bladder cancer patients from The Netherlands, 23% of all variant tumors identified within the registry presented with NMI disease.…”

Classification of urothelial tumors

“…Les recommandations de l'OMS lorsque ce contingent est présent sont de refaire une résec-tion de contrôle quelle que soit la quantité de muscle présent sur la première exérèse. Certains auteurs ont tenté cependant de souligner que ce contingent était surtout de mauvais pronostic lorsqu'il était prédominant, supérieur à 50 %, cela n'est pas encore bien clarifié dans la littérature où sont décri-tes des évolutions à stade égal comparable à celles des carcinomes urothéliaux classiques ou plus péjoratives [24][25][26][27][28].…”