Prognostic significance of perirenal infiltration in renal cell carcinoma (<7 cm)

Pathologic stage is the most accurate prognostic factor of renal cell carcinoma. We evaluated whether perirenal fat infiltration is a significant factor in tumors 7 cm or less in size. We retrospectively reviewed the record of 164 cases of tumors 7 cm or less in size. We divided the patients into two groups according to the presence of perirenal fat infiltration (group A, pT1; group B, pT3a). We evaluated relationships, recurrence-free survival and disease-specific survival according to clinicopathologic parameters. Statistical differences were calculated by log-rank test. A total 131 patients were included in group A, with a mean age of 55.8 years, average tumor size was 4.2 cm, and a mean follow-up period of 43 months. Group B included 33 patients, with a mean age of 55.9 years, an average tumor size of 4.1 cm, and a mean follow-up period of 38 months. There was no significant difference in disease-specific survival; however, recurrence-free survival showed significantly different between two groups (group A: 95.5%, group B: 84.4%). In this study, perirenal fat infiltration proved to be an independent prognostic factor for predicting disease-free survival in patients with tumors of 7 cm or less in size. Therefore, as this study showed, the presence of perirenal fat infiltration requires stricter follow-up planning, even in small renal cell carcinoma.