A National Study of the Rate of Benign Pathology After Partial Nephrectomy for T1 Renal Cell Carcinoma: Should We Be Satisfied?

<b>Objectives</b>: To determine the rate of benign pathology in cT1 tumors following partial nephrectomy in the Netherlands, thereby evaluating the rate of overtreatment. <b>Methods:</b> Data were collected from a nationwide database containing histopathology of resected renal tissue from 2014 to 2022. Patients who underwent partial nephrectomy for suspected RCC staged T1a-b were extracted for analysis. Data are shown in percentages, and multivariable logistic regression was performed to determine predictive factors for benign pathology. <b>Results</b>: 3409 cases were analyzed, of which 403 (12%) were benign and 3006 (88%) malignant. Subtype analysis showed 2126 (62%) cases of clear-cell RCC, followed by 604 (18%) of papillary RCC and 344 (10%) oncocytomas. Mean age was 63 years among patients with malignant pathology versus 65 years for patients with benign lesions (<i>p</i> < 0.001). Mean tumor size was 3.2 cm for malignant pathology and 2.9 cm for benign (<i>p</i> < 0.001). The rates of benign and malignant pathology did not change between 2014 and 2022 (<i>p</i> = 0.377). Multivariable regression showed age ≥ 65 years (65-79 years [OR 1.881, <i>p</i> = 0.002], ≥ 80 years [OR 3.642, <i>p</i> < 0.001]) and tumor size (OR 0.793, <i>p</i> < 0.001) as predictors for benign pathology. The main limitation of this study is that we do not know the biopsy rate of our cohort. <b>Conclusion:</b> This study reports a low rate of 12% benign pathology after partial nephrectomy in the Netherlands. It remains debatable whether these rates are acceptable, or if renal tumor biopsies should be utilized more frequently to reduce overtreatment.