Contralateral metachronous tumor occurrence is more frequently associated with distant metastases or postoperative intrarenal recurrence in renal cell carcinoma patients

Objective: To analyze the prognosis of patients with sporadic bilateral renal cell carcinoma (RCC). Methods: From January 1979 to December 2007, 984 patients with sporadic RCC underwent surgery at our department. Of these, 53 patients (5.7%) presenting with bilateral RCC were included in this retrospective analysis. Results: Thirty‐one of the 53 bilateral RCC patients had synchronous RCC, and 22 had metachronous RCC. Distant metastases by the time of the bilateral tumor occurrence were found in four patients (13%) in the synchronous group and in 10 patients (48%) in the metachronous group. No difference was found between the two groups in terms of overall survival. In contrast, survival after the second surgery in the metachronous group was significantly lower than that after the first surgery (P < 0.001) in the synchronous group (P = 0.02). In addition, the incidence of local recurrence after partial nephrectomy was higher in the metachronous group (26%) compared to the synchronous group (4%, P = 0.04) or the unilateral RCC patients (0.4%, P < 0.01). Conclusions: Metachronous occurrence of RCC in the contralateral kidney is associated with an unfavorable prognosis, suggesting that metachronous contralateral tumors might be metastasis of the original tumors. A stricter follow‐up schedule is advisable for metachronous bilateral RCC patients.