Estimation of the incidence of urachal cancer: A systematic review and meta-analysis of registry-based studies

Abstract

Background: Urachal cancer (UrC) is a rare disease with limited availability of representative incidence and clinical data. Although, the prevalence is accounting for less than 1% of bladder tumors, the 5-year survival rate is around only 50% for patients with resectable tumors, and even worse for patients with metastatic disease. Due to the lack of comprehensive prospective studies, our current knowledge of UrC is still limited.

Objective: The present study aimed to summarize the available registry-based studies with unselected UrC patients to evaluate its incidence and clinicopathological characteristics.

Material and methods: We conducted a systematic literature search of registry-based UrC publications on the 15th of May 2023 in 5 databases, which identified 4,748 publications. After duplicate removal and selection by 2 independent investigators, 6 publications proved to be appropriate for the final meta-analysis. Estimated incidence and clinicopathological parameters were extracted.

Results: Estimated incidence ranged between 0.022 and 0.060/ 100.000 person-years, with the highest occurrence in Japan and the lowest in Canada, while the random effect model calculated an overall incidence rate of 0.04 (95%CI: 0.03-0.05) 100.000 person-years. The median age at first diagnosis was 60 years (range: 58-64). The female to male ratio was 2:3. Lymph node or distant metastases were present in 9% and 14% of patients. The predominant tumour type was adenocarcinoma (86%) followed by urothelial carcinoma (12%) and squamous cell carcinoma (2%). The 5-year survival rate was 51.0% with 95%CI: 45.2-57.4.

Conclusions: Our study provides an up-to-date comparison of estimated incidence rates between 6 countries of 3 continents based on rigorously selected registry-based studies. The results suggest low incidence rates for UrC with considerable geographic differences. The present meta-analysis provides unbiased registry-based data on the incidence, clinicopathological parameters and survival of UrC.

Keywords: Adenocarcinoma; Bladder cancer; Epidemiology; Incidence; Registry; Urachal cancer; Urachus carcinoma.