Abstract
BACKGROUND: Renal cell carcinoma rarely metastasizes to the bladder, and its biological behavior is not yet fully understood. CASE PRESENTATION: In our case (54-year-old Japanese woman), computed tomography evaluation suggested the presence of a bladder metastasis, associated with additional metastases in the lungs, mediastinal lymph nodes, ribs, and renal bed, 4 years after radical nephrectomy for renal cell carcinoma. The histological findings of the metastatic bladder tumor were consistent with those of clear cell carcinoma. The mediastinal lymph node, rib, and renal bed metastases responded to treatment with an immune checkpoint inhibitor administered for 12 months after surgery for the bladder and lung metastases. In patients with bladder metastasis, absence of metastases in other organs and an interval of more than 1 year after nephrectomy are known to be favorable prognostic factors. Interestingly, in our case, the bladder metastasis was detected more than 1 year after nephrectomy, which was a favorable factor, but there were also metastases in other organs, which was an unfavorable factor. Therefore, we reviewed the literature, including that pertaining to targeted therapy and immune checkpoint inhibitor therapy published in the last two decades, to analyze the clinical significance of the presence of additional metastasis in other organs in renal cell carcinoma (clear cell type, which is the predominant subtype) patients with bladder metastasis. CONCLUSIONS: Patients with bladder metastasis after nephrectomy for renal cell carcinoma also having metastases in other organs may respond to targeted therapy and immune checkpoint inhibitor therapy. This may suggest that the interval to relapse in the bladder after nephrectomy may be a more important prognostic factor than the presence of synchronous metastases in other organs.