The objective of this study was to determine the incidence of local treatment and incidence of metastasis for patients with a solitary small renal mass (SRM) (≤4cm) initiating active surveillance (AS). Patients enrolled in the Canadian Kidney Cancer information system (CKCis) between January 2011 and January 2023 with a solitary renal mass ≤4cm opting for AS were included. The primary outcome was local treatment progression, achieved if the patient received definitive local treatment after initiating AS. The secondary outcomes were growth rate progression (>0.5cm/year), size progression (>4cm), composite progression (either size or growth rate progression) and development of metastases. CKCis included 1,393 patients who initiated AS for a SRM ≤4cm during the study period. At a median follow up of 4.0 years (95%CI 2.1-6.4), 238 patients received local treatment and of these, 195 were nephron-sparing. Two- and five-year cumulative incidence of treatment were 8.4% (95% confidence interval (CI) 6.9-10) and 21% (95%CI 19-24%) respectively. Twenty-nine patients developed metastasis. Two- and five-year cumulative incidence of metastasis were 0.67% (95%CI 0.32-1.3%) and 2.3% (95%CI 1.5-3.5%) respectively. Of the 29 patients who developed metastases, 23 had progressed using size or growth rate cutoffs, and 7 had received local treatment with curative intent, prior to the identification of metastases. Patients choosing surveillance for a SRM have low cumulative incidence of local treatment and metastasis at 5 years, demonstrating AS is a safe initial management approach.
Lavallée et al. (Fri,) studied this question.
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