Purpose: We conducted a systematic review of the literature on primary clear cell carcinoma (CCC) of the urinary bladder.
Methods: A literature search using keywords and MeSH terms related to "clear cell carcinoma", "clear cell adenocarcinoma", "mesonephroma" and "urinary bladder" in EMBASE, MEDLINE and Cochrane Central Register of Controlled Trials was performed. A manual search was performed with web-based search engine Google Scholar. Reference lists of the included studies were screened for additional articles. Articles up till 16th July 2020 were retrieved. Observational human studies on primary CCC in urinary bladder with English full-text were included for further analysis.
Results: 904 articles were identified and 44 articles were included for further analysis. Data including clinical features, tumour characteristics, treatment and oncological outcomes were reviewed. There were 70 patients (44 females and 26 males) reported in literatures and included in this review. Gross haematuria was the most common presentation (79.7%), followed by irritative urinary symptoms (47.5%). Regarding the histology, tubulocystic pattern is the most common histologic pattern (49.1%), and 52.6% had muscle invasion. Most cases were CK7 (96.6%) and CK20 (88.9%) positive. CA125 (96%) was commonly positive, indicating its potential origin from mullerian duct. Most patients received surgery (95.5%) as primary treatment. However, the oncological outcomes were unsatisfactory with a 2-year survival rate of 60.0%.
Conclusion: Clear cell carcinoma is an uncommon subtype of bladder cancer which can be diagnosed by histology and immunohistochemical staining result. The majority of patients presented with muscle invasion and had a poor survival despite aggressive treatment.
Keywords: Bladder cancer; Clear cell carcinoma; Systematic review; Urinary bladder.