Increasing detection rate of benign renal tumors: evaluation of factors predicting for benign tumor histologic features during past two decades.

OBJECTIVES: To determine whether the detection of benign renal tumors is increasing and to identity the predictors of benign histologic features. The detection of renal cortical tumors has increased with the increased use of abdominal imaging. Current imaging and biopsy techniques cannot predict the renal tumor histologic features with complete accuracy, and many patients undergo surgery for benign lesions.
METHODS: The Columbia Urologic Oncology Database was reviewed, and 1244 patients who had undergone partial or radical nephrectomy from 1988 to 2007 were identified. A cohort of 775 patients with a tumor diameter of <or.0 cm, nonmetastatic disease, and nonfamilial disease was selected. Univariate and multivariate logarithmic regression analyses were used to determine the parameters to predict for benign histologic features.
RESULTS: The proportion of renal surgery for benign tumors of <or.0 cm in diameter has increased annually. When patients were stratified by the year of surgery, the proportion of benign tumors was 5.0% before 1998, 15.2% from 1998 to 2003, and 21.2% from 2004 to 2007. The mean diameter of benign and malignant tumors was 3.0 and 3.5 cm, respectively, and the mean tumor diameter significantly decreased during the study period (P = .006). Using multivariate analysis, the year of surgery, tumor diameter, and female sex were independent predictors of benign histologic features (P < .05). Age, incidental diagnosis, body mass index, and race were not significant predictors (P > .05).
CONCLUSIONS: Even when controlling for tumor diameter and sex, the incidence of benign tumors detected at renal surgery at our institution has increased significantly in the past 2 decades.