Objectives: To examine patient and clinicopathological features of malignant urachal neoplasms (MUN) in a population-based cohort, to investigate survival outcomes, and to review the current evidence that exists in the literature.
Material and methods: The Surveillance, Epidemiology, and End Results database was used to identify microscopically confirmed MUN cases diagnosed between 1988 and 2012. Kaplan-Meier analysis was used to determine median and 5-year overall survival (OS) as well as cancer-specific survival (CSS) rates. Cox proportional hazards model was employed to identify variables independently associated with cancer-specific mortality. A systematic literature review was conducted in line with the PRISMA statement.
Results: A total of 420 patients with MUNs were identified. The majority were white (77.6%) and male patients (59%) who presented with low-grade (62.1%), mucinous, noncystic adenocarcinomas (42.9%). From the cohort, 19%, 15.2%, 29.5%, and 30.5% of the patients presented with American Joint Committee on Cancer Stage I to IV disease, respectively. Cancer-directed surgery was performed in 86.5% of the patients. The most common procedure performed was partial cystectomy (52.4%) followed by local tumor excision (20.7%). Median OS was 57 months (95% CI: 41.6-72.4), and median CSS was 105 months (95% CI: 61.5-148.5). Five-year OS and CSS rates were 51% and 57%, respectively. Grade and stage were independently associated with cancer-specific mortality. Mortality rates did not differ between patients who underwent partial cystectomy and radical cystectomy/exenteration (P = 0.165), even after controlling for tumor stage. A total of 16 studies reporting on 585 patients were systematically reviewed, and relevant outcomes were summarized in the Supplemental material.
Conclusions: MUNs are usually low-grade, mucinous, noncystic adenocarcinomas diagnosed at advanced stages. Overall, the prognosis is poor, and high-grade and disease stage are independently associated with cancer-specific mortality.
Keywords: Adenocarcinoma; Bladder; Cancer; Malignant neoplasms; Urachus.
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