Purpose: A paradigm shift in the management of small renal masses has increased utilization of active surveillance. However, questions remain regarding safety and durability in younger patients.
Materials and methods: Patients aged 60 or younger at diagnosis were identified from the Delayed Intervention and Surveillance for Small Renal Masses registry. The active surveillance, primary intervention, and delayed intervention groups were evaluated using ANOVA with Bonferroni correction, χ2 and Fisher's exact tests, and Kruskal-Wallis and Wilcoxon signed-rank tests. Survival outcomes were calculated using the Kaplan-Meier method and compared with the log-rank test.
Results: Of 224 patients with median followup of 4.9 years 30.4% chose surveillance. There were 20 (29.4%) surveillance progression events, including 4 elective crossovers, and 13 (19.1%) patients underwent delayed intervention. Among patients with initial tumor size ≤2 cm, 15.1% crossed over, compared to 33.3% with initial tumor size 2-4 cm. Overall survival was similar in primary intervention and surveillance at 7 years (94.0% vs 90.8%, log-rank p=0.2). Cancer-specific survival remained at 100% for both groups. There were no significant differences between primary and delayed intervention with respect to minimally invasive or nephron-sparing interventions. Recurrence-free survival at 5 years was 96.0% and 100% for primary and delayed intervention, respectively (log-rank p=0.6).
Conclusions: Active surveillance is a safe initial strategy in younger patients and can avoid unnecessary intervention in a subset for whom it is durable. Crucially, no patient developed metastatic disease on surveillance or recurrence after delayed intervention. This study confirms active surveillance principles can effectively be applied to younger patients.
Keywords: watchful waiting, kidney neoplasms, disease progression.