Metastatic renal cell carcinoma risk according to tumor size.

PURPOSE Recent evidence suggests significantly discordant findings regarding tumor size and the metastasis risk in renal cell carcinoma cases. We present our experience with renal cell carcinoma. We evaluated the association between tumor size and the metastasis risk in a large patient cohort. MATERIALS AND METHODS Using our prospectively maintained nephrectomy database we identified 2,691 patients who were treated surgically for a sporadic renal cortical tumor between 1989 and 2008. Associations between tumor size and synchronous metastasis at presentation (M1 renal cell carcinoma) were evaluated with logistic regression models. Metastasis-free survival after surgery was estimated using the Kaplan-Meier method in 2,367 patients who did not present with M1 renal cell carcinoma and were followed postoperatively. RESULTS Of the 2,691 patients 162 presented with metastatic renal cell carcinoma. Only 1 of 781 patients with a tumor less than 3 cm had M1 renal cell carcinoma at presentation and tumor size was significantly associated with metastasis at presentation (for each 1 cm increase OR 1.25, p <0.001). Of the 2,367 patients who did not present with metastasis metastatic disease developed in 171 during a median 2.8-year followup. In this group only 1 of the 720 patients with renal cell carcinoma less than 3 cm showed de novo metastasis during followup. Metastasis-free survival was significantly associated with tumor size (for each 1 cm increase HR 1.24, p <0.001). CONCLUSIONS In our experience tumor size is significantly associated with synchronous and asynchronous metastases after nephrectomy. Our results suggest that the risk of metastatic disease is negligible in patients with tumors less than 3 cm.