Urachal carcinoma (UrC) is a rare and poorly investigated disease. Our current knowledge is mainly based on single-institutional studies. Despite growing interest in UrC, the included case numbers in recently published studies are still low. Therefore, we aimed to provide a comprehensive meta-analysis on the clinical, prognostic, and therapeutic aspects of UrC.

A systematic Medline/PubMed search was performed on UrC using the terms "urachal carcinoma," "urachal cancer," and "urachus." Original articles and reviews in English language with case numbers>10 were selected.

The vast majority (91%, 489/532) of UrCs are diagnosed at later stages (Sheldon≥III) when the tumor invades the urinary bladder. About 21% (136/646) of UrC patients have distant metastasis at first presentation. Although for patients with non-metastatic UrC surgical treatment provides an acceptable disease control, the systemic treatment of patients with progressed/metastatic UrC-in lack of prospective clinical trials-are less well established. Comparing cisplatin-based and 5-FU-based therapies in 74 published UrC cases, we found the latter to be superior in terms of radiographic response rates (9% vs. 44%, P = 0.043), but the combination of these 2 therapies provided the lowest progression rate (14%) with a similarly high response rate (43%).

Owing to the lack of evidence-based guidelines, the therapy of UrC remains challenging. Given the infrequency of UrC, large prospective studies comparing different systemic therapies can hardly be conducted. Our metadata indicates that 5-FU-containing chemotherapy regimens are more effective than cisplatin-based treatment modalities, whereas their combination seems to provide the strongest antitumor effect. Nevertheless, in the lack of evidences from prospective clinical trials, therapeutic decision-making necessarily remains on an individual basis. In this situation, targeted therapies may provide a reasonable alternative. Therefore, better understanding of the molecular background of UrC is needed to rationalize treatment decisions in UrC.