Clinical features of renal cell carcinoma less than 25 millimeters in diameter

Background: We retrospectively investigated the clinicopathological features and prognosis of patients who underwent surgical treatment at our department for renal cell carcinoma (RCC) less than 25 mm in diameter. Methods: Of the 158 patients who underwent surgical treatment between April 1975 and April 1998, 16 (17 kidney, 10.1%) were included in this study. The study included 11 men and 5 women (ratio: 2.2). The age range was 35–76 years (average: age 53). The right kidney was involved in 9, left kidney in 6 and bilateral kidneys in 1 patient. The follow‐up period was 26–157 months (mean: 86 months). Results: Thirteen tumors (81.2%) were incidental carcinomas. No patients had a tumor of rapid growing type. Radical nephrectomy was performed for 12 kidneys (70.6%), simple nephrectomy for 2 (11.8%) and partial nephrectomy for 3 (17.8%). Seven patients (43.7%) received interferon‐α as postoperative adjuvant therapy. All tumors were pathologically classified as expansive type; 11 (64.8%) as clear cell carcinoma; 3 (17.6%) cyst‐associated, and 3 (17.6%) papillary. Nine (52.9%) tumors were grade 1, and 8 (47.1%) were grade 2. Fourteen patients were pNo and V(–). The 5‐ and 10‐year survival rates were excellent (100%). Conclusion: The features of small RCCs less than 25 mm were as follows: many tumors were incidental to clear cell carcinomas; all tumors were low grade, low stage and expansive type; no tumors showed acute phase reactants; and few tumors were of the solid type. Thus, the prognosis seemed to be excellent.