Small renal masses in young adults: Insights from a large contemporary multi-institutional Registry

Introduction & Objectives: With a peak of incidence in the sixth decade, renal cell carcinoma (RCC) most frequently affects older patients while being an uncommon entity in younger populations. The aim of this study is to describe the clinical-pathologicalcharacteristics and surgical outcomes of young patients harboring small renal masses suspected of RCC leveraging data from a large multi-institutional surgical database, aiming to provide insights to support clinicians in shared decision-making. Materials & Methods: After Institutional Review Board approval, we retrospectively queried a multi-institutional database promoted by the EAU Young Academic Urologists (YAU) Renal Cancer working group to select patients with a single cT1-2N0M0 renal mass treated with either partial (PN) or radical (RN) nephrectomy at referral 13 centers worldwide from 2015 to 2023. For this study we included young adults (patients aged 20–39 years according to the definition of the Adolescent and Young Adult Oncology Progress Review Group) with a single cT1aN0M0. Baseline tumour and clinical characteristics as well as final pathology data were analyzed. Results: Overall, 383 patients were included. Median age was 34 years (IQR 31-38) years (59% males). The selected cohort showed a favorable baseline health status: median BMI 23.4 (IQR 20.9-26.5), Charlson comorbidity Index < 2 in 88% and ASA score <3 in 98% of the patients as well as preserved baseline renal function in most patients (median serum creatinine (sCr) of 0.86 mg/dl; median eGFR of 95 ml/kg/m2). The median RENAL score was 6 (IQR 5-8). Most patients were treated with PN (89%) using a minimally-invasive approach (59% laparoscopic, 36% robotic). Concerning pathological findings, median tumor size was 3.4 cm (IQR 3.0 – 3.7). The most frequent malignant histotype was clear-cell RCC (64%) followed by papillary RCC (9%). RCC grade was <3 in 96% of cases. Pathological upstaging was recorded in 3.3% of patients. One out of ten patients harbored a benign renal mass. Conclusions: In carefully selected young patients with small renal masses suspected of RCC who were deemed candidates for surgery, we found a relatively high proportion of malignant tumors, yet of low grade. While they should be interpreted with caution due to the potential selection bias, our findings might support shared decision-making toward active intervention in properly selected and well-informed surgical candidates.