Oncologic and Functional Outcomes of Active Surveillance and Ablative Therapy for Small Renal Masses: A Systematic Review and Meta-Analysis

Abstract

Purpose: To compare the oncologic and renal functional outcomes of active surveillance (AS) and ablative therapy (AT) in patients with small renal masses (SRMs). Materials and Methods: A systematic search of PubMed, Cochrane, and Web of Science identified 78 studies: 9 on AS, 68 on AT, and 1 comparative study. Outcomes included overall survival (OS), cancer-specific survival (CSS), development of metastasis, posttreatment chronic kidney disease (CKD), and estimated glomerular filtration rate (eGFR). Subgroup analyses were conducted by tumor size (<3 cm), age (<75 and >= 75 years), and T1a stage. Results: AT demonstrated higher OS compared with AS (84.8% vs 74.0%). CSS was comparable between AS (99.6%) and AT (93.5%). Metastasis rates remained low in both groups (0.6% for AS; 0.9% for AT). CKD was reported in 12.0% of AT-treated patients, while data were limited for AS. Posttreatment eGFR was similar in both strategies. Subgroup analyses confirmed the consistency of these findings across patient and tumor characteristics. Significant heterogeneity was noted across studies. Conclusions: Both AS and AT appear safe and effective for managing SRMs, with favorable CSS and similar posttreatment renal function. AS may be preferable in older or comorbid patients, whereas AT, particularly image-guided approaches, offers a minimally invasive alternative for those requiring active treatment. Prospective comparative studies are warranted to refine patient selection and optimize management strategies.