Houston Methodist Hospital / Michigan State University College of Human Medicine
Introduction: Carcinoma of the urachus is a rare disease, which accounts for less than 1% of all bladder cancers with an estimated annual incidence of 1 in 5 million individuals. Given the rarity of urachal cancer, contemporary diagnostic and treatment evidence are mostly derived from single-institution case series. Contemporary population-based data remains limited. Therefore, we aimed to define the patient characteristics, clinicopathological features, and survival outcomes of patients diagnosed with urachal carcinoma.
Methods: The National Cancer Database from 2006 to 2016 was used to identify patients diagnosed with urachal carcinoma. Patients were stratified by staging subgroups and receipt of partial or radical cystectomy. Kaplan Meier analyses determined median and 5-year overall survival (OS) rates and univariable and multivariable analyses were conducted to identify clinical and pathologic characteristics associated with OS duration. Subgroup analyses were conducted to evaluate the association between systemic therapy and survival for metastatic disease.
Results: A total of 841 patients with urachal carcinoma were identified. The most common histologic subtypes were non-mucinous adenocarcinoma (39.6%), and mucinous adenocarcinoma (39.1%). Approximately half of the patients had =cT2 disease, and 14.3% (n=114) had metastasis at diagnosis. The most common surgical management was partial cystectomy (PC) 60% (n=508). Regional lymph node dissection was performed for 377 patients (44.8%), of which 73 patients (19.4%) had nodal involvement. The median OS was 59 months, and 5-year survival rate was 49%. Among patients with localized disease, we found no significant difference in survival between those treated with partial and radical cystectomy (HR 1.75, 95% CI 0.72-4.3). Further, among those with metastatic disease, receipt of systemic therapy was not associated with prolonged survival benefit (HR=0.79, 95% CI 0.37-1.65).
Conclusions: Urachal carcinoma is rare, high-risk cancer with predominant histologic types of either non-mucinous adenocarcinoma or mucinous adenocarcinoma. These observational data, while limited due to confounding by indication and selection biases, do not demonstrate significant associations between particular treatment approaches and survival. Further prospective research is needed to improve patient outcomes and develop standardized treatment approaches for this rare malignancy.
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