[RENAL CELL CARCINOMA METASTASIS TO BLADDER DURING MOLECULAR TARGETED THERAPY WITH PAZOPANIB: REPORT OF TWO CASES].

Renal cell carcinoma (RCC) metastasis to the bladder is rare. We report two cases that occurred metachronously during pazopanib treatment for other metastases. To our knowledge, this is the first report to demonstrate bladder metastasis from RCC during molecular targeted therapy with pazopanib. (Case 1) A woman in her 60s was referred to our department for evaluation of an incidental right renal tumor. Dynamic CT showed a 6 cm renal cell carcinoma. In February 201X she underwent laparoscopic right radical nephrectomy, revealing clear cell carcinoma (grade 1>2), stage pT3aN0M0. In February 201X+1 she complained of left pelvic pain. She was found to have metastasis to two iliac bones and an occipital bone. She received pazopanib, in addition to a bone modifying agent and radiotherapy for the iliac bones. After 8 months, she complained of asymptomatic gross hematuria in spite of having stable disease for bone metastasis. Cystoscopy showed a 1 cm solitary sessile nonpapillary tumor on the posterior wall. She underwent transurethral resection of bladder tumor (TUR-BT). Histological examination showed metastatic RCC. Thereafter she received sequential therapies (axitinib, sunitinib, nivolumab). She remains alive without recurrence in the bladder 51 months after TUR-BT. (Case 2) A woman in her 60s presented to our department with a complaint of painless gross hematuria. A dynamic CT showed an 8.5 cm renal cell carcinoma and multiple lung metastases. In March 201Y she underwent right radical nephrectomy, revealing clear cell carcinoma (grade 2>3), stage pT2aN0M1. In June 201Y she started pazopanib. After 9 months CT showed a bladder tumor in addition to progression of lung metastases. Cystoscopy showed a 1 cm solitary sessile nonpapillary tumor at dome. She underwent TUR-BT. Histological examination showed metastatic RCC. She had no recurrence in the bladder during follow-up although she died of RCC.