Active surveillance (AS) refers to the monitoring of renal tumor size changes through regular abdominal imaging, and receiving delayed interventional treatment if tumor progression occurs during the follow-up period. Awaiting surveillance is different from active surveillance in that patients with more serious comorbidities are not suitable for active treatment and are under observation until symptoms appear and then treated symptomatically without regular imaging.
A multicenter prospective registry study DISSRM (Delayed Intervention and Surveillance for Small Renal Masses) for small renal masses (SRMs, tumors ≤4 cm in maximum diameter) showed that active surveillance was associated with better overall survival at 2 years compared with active treatment for small renal masses. The 2-year overall survival rates for patients with small renal tumors were similar, 98% and 96%, respectively; the 5-year overall survival rates were slightly lower in the active surveillance group, 92% and 75%, respectively (P=0.06); and the 7-year overall survival rates were worse in the active surveillance group, 91.7% and 65.9%, respectively (P=0.01). Patients in the AS group were older, had worse ECOG scores, more severe comorbidities, smaller tumors, and a higher proportion of multiple and bilateral renal tumors.
For most patients with advanced age and comorbidities in SRMs, the risks associated with surgical anesthesia and other comorbidities are often higher than the tumors themselves. Prospective studies have shown that patients with SRMs in the AS group have an overall 5-year survival rate of 53% to 90%, a 5-year tumor-specific mortality rate of 0.2% to 1.9%, and a 5-year progression-free survival rate of 97% to 99%. AS is a viable option for patients with older or frail SRMs. The American Urological Association recommended AS as a treatment option for patients with high-risk surgical factors and comorbidities in its 2009 guidelines for the management of stage T1 renal tumors. The absolute indications are: high risk of surgical anesthesia or life expectancy<5 years; relative indications: risk of end-stage renal disease if treated, SRM<1cm or life expectancy<10 years. However, long-term AS is not recommended for young patients without co-morbid SRMs.