Bladder metastasis from renal cell carcinoma: retrospective analysis of 65 reported cases

This study was carried out to clarify the presentation, treatment options, and prognosis of renal cell carcinoma (RCC) metastasis to the bladder in which we do not yet have a comprehensive understanding. A systematic Medline, Web of Science, Embase, Google, and Ichushi Web search was performed to identify articles describing RCC metastasis to the bladder. The final cohort included 65 patients. The majority (75%) experienced gross hematuria at the point of diagnosis of RCC. RCC metastasis to the bladder occurred both synchronously (23%) and metachronously (77%), and the median time for metachronous bladder metastasis following the diagnosis of RCC was 33 months. Of the 58 patients whose metastatic data were available, 36 (62%) had metastasis to the bladder only, while 22 (38%) had additional sites of metastasis. On pathology, clear cell carcinoma was the most common histology (92%) and all bladder tumors were consistent with RCC metastasis; the median tumor size was 2.1 cm, and two-thirds of cases were superficial (non-muscle invasive) disease. The 2-year cancer-specific survival rate in patients with solitary bladder metastasis was 71.1%, which was significantly higher than in patients with additional distant metastasis (25.8%, p = 0.007). Regarding the interval after the diagnosis of primary RCC, the 2-year cancer-specific survival rate in patients who experienced bladder metastasis after more than a 1 year follow-up was 58.4%, compared to 34.6% in their counterparts (p = 0.063). A curative resection may provide a good possibility of long-term survival, particularly in those with a solitary bladder metastasis and/or a long interval after nephrectomy.