Use of delayed intervention for small renal masses initially managed with active surveillance

Introduction: A number of patients who elect active surveillance of their small renal masses (≤4 cm) subsequently pursue delayed intervention (DI). The indications, timing, and rates of DI have not been well determined prospectively. Materials and methods: Data from Delayed Intervention and Surveillance for Small Renal Masses, a prospective, multi-institutional registry was utilized to evaluate factors associated with DI between 2009 and 2018. Results: Of 371 patients enrolled in AS, 46 (12.4%) pursued DI. Patients who pursued DI spent a median 12 months on surveillance (interquartile range 5.5–23.6), had better functional status (P < 0.01), and had greater median growth rate vs. those who remained on surveillance (0.38 vs. 0.05, P < 0.001). Indications for intervention included growth rate >0.5 cm/y for 23 (50%) patients, patient preference for 22 (47.8%) patients, and qualification for renal transplant in 1 (2.2%) patient. Thirty-two patients (69.6%) underwent nephron-sparing surgery, 5 (10.9%) underwent radical nephrectomy, and 9 (19.6%) underwent percutaneous cryoablation. Renal mass biopsy was utilized in 37 (11.4%) and 15 (32.7%) patients in the AS and DI arms, respectively (P = 0.04). No patients experienced metastatic progression or died of kidney cancer. Conclusions: As nearly 50% of patients pursue DI secondary to anxiety in the absence of clinical progression, comprehensive counseling is essential to determine if patients are suitable for a surveillance protocol. AS remains a safe initial management option for many patients but may not be a durable strategy for patients who are acceptable surgical candidates with an extended life expectancy. DI does not compromise oncologic outcomes or limit treatment options.