Urachal carcinoma: The journey so far and the road ahead.

Urachal carcinoma, a rare cancer arising from urachus, accounts for about 1% of bladder cancer. The diagnosis at stage I shows about 63% 5-year survival whereas only 8% of the patients at stage IV shows a 5-year survival. Above 90% of urachal carcinomas are adenocarcinomas and most of the urachal carcinoma cases are invasive, showing a high resemblance to adenocarcinoma of various origins, making it hard for a conclusive diagnosis. Even though inconclusive, immunohistochemistry can play a significant role in identifying urachal carcinoma. Most cases show the biomarkers CK20 and CDX2, whereas CK7 and β-catenin are expressed at a lesser frequency. Due to the few cases available, there is a lack of evidence regarding specific markers differentiating urachal carcinoma from colorectal or primary bladder adenocarcinomas. In addition to immunohistochemistry, genomic characterization is emerging to play a role in the classification and treatment of the disease. Urachal carcinoma has been reported to have a molecular level similarity with colorectal malignancies regarding certain gene expressions. The TP53 mutations inactivating the tumor suppressor can probably be explored as a possible target in treating urachal carcinoma. Additionally, certain targets identified in gastric and breast cancer along with anti-HER2 treatment strategies can be explored. Immuno-oncology utilizes immune checkpoint inhibitors for the treatment of MSI-H tumors whereas a combination of tyrosine kinase inhibitors along with immune checkpoint inhibitors are being studied to treat MSI stable tumors. The article is an in-depth overview of urachal carcinoma addressing the current landscape with an emphasis on the future scenario.