Active Surveillance of Renal Tumors

Asymptomatic solid small renal masses are an increasingly common clinical entity. While most small renal masses are malignant, many have limited metastatic potential as evidenced by a significant proportion of benign and indolent pathology, slow growth rates under surveillance, and very low rates of metastatic progression. Active surveillance has emerged as a management option for well-selected patients. Prospective cohorts with defined inclusion criteria for active surveillance and triggers for delayed intervention demonstrate that small renal masses can be safely managed on active surveillance with comparable survival outcomes, renal function, and quality of life compared to patients undergoing primary intervention. While outcomes continue to mature, the growing data is promising not only for elderly and comorbid patients but also potentially a more broadly selected population with small renal masses. Expanding inclusion criteria for active surveillance will depend on better initial risk stratification, based on tumor and patient characteristics, emerging diagnostic modalities, and shared decision-making with patients showing signs of progression. There is no consensus on optimal growth rate thresholds or other triggers for intervention, but renal mass biopsy and novel imaging modalities may be increasingly used in this setting. Active surveillance is currently underutilized on a population-level, and long-term follow-up will likely solidify its role in the management of renal tumors.