We evaluated oncologic risks in the cohort of Asian patients with radiographic cystic renal lesions who underwent active surveillance or surgical intervention.

We enrolled 190 radiographically confirmed renal cystic lesions, which was classified as Bosniak score (2019 version) ≥ 2F, from the medical database of Keelung, Taipei and Linkou Chang Gung Memorial Hospital since 2000/1 to 2023/11. The lesions managed with either active surveillance (AS) ± delayed surgical intervention or immediate surgical intervention. Association of radiographical characteristics and pathology was evaluated.

We identified 190 radiographically confirmed renal cystic lesion in 179 patients. 167 renal lesions underwent active surveillance, in which 17 were proceeded delayed intervention eventually. 23 lesions managed surgical intervention. Of these, 40 were resected. Pathologically, 65% (n=19) demonstrated malignant pathology. Of intervention cohort, intermediate surgical intervention was associated with higher Bosniak score (P<0.00). On active surveillance, 5 cystic lesions progressed according to Bosniak score. The longest time from diagnosis to progression of these progressive lesion was 24 months. One of these 5 cystic lesion underwent radical nephrectomy, which pathological report showed benign cyst, and the others do surveillance or loss follow-up. No recurrence was found in both surveillance group and intervention group. Kaplan-Meier curve of Progression-Free survival rate of different intervention showed no significant difference (P=0.566).

Over 50% of resected cystic renal lesions which classified as Boasniak IV demonstrated malignant pathology. No patient had a significant progression beyond 24 months. Despite this finding, active surveillance ± delayed intervention is a safe and effective management option for most radiographic cystic renal lesions.