Predictors of benign histology in clinical T1a small renal masses: A large multicenter cohort study

Purpose:The increasing detection of small renal masses (SRMs, ≤4 cm) has raised concern for overdiagnosis and overtreatment, as a substantial proportion of these lesions prove to be benign.Identifying preoperative predictors of benign histology may help refine treatment selection and reduce unnecessary surgery.Materials and Methods: We performed a retrospective multicenter cohort study including patients who underwent partial or radical nephrectomy for clinical T1a renal masses at eight tertiary referral centers in South Korea between 1990 and 2023.Clinicodemographic, laboratory, and radiologic variables were compared between benign and malignant tumors.Independent predictors of benign pathology were identified using multivariable logistic regression.Results: Among 5,713 surgically treated renal masses, 289 (5.1%) were benign.Compared with malignant tumors, benign lesions were more common in females (58.8% vs. 28.2%,p<0.001) and were associated with lower body mass index (BMI) (23.60 kg/m² vs. 24.80kg/m², p<0.001), higher estimated glomerular filtration rate (eGFR) (93.67 mL/min/1.73m² vs. 84.65 mL/min/1.73m², p<0.001), and smaller tumor size (20.60 mm vs. 24.86mm, p<0.001).On multivariable analysis, female sex (odds ratio OR 3.126, p<0.001), tumor size ≤2 cm (OR 2.335, p<0.001), lower BMI (OR 0.910 per kg/m², p<0.001), and higher eGFR (OR 1.023 per mL/ min/1.73m², p<0.001) were independently associated with benign histology.Conclusions: Female sex, lower BMI, and smaller tumor size are significant preoperative predictors of benign histology in SRMs.These findings support consideration of active surveillance or percutaneous biopsy in patients with multiple favorable predictors to minimize overtreatment.