PURPOSE: To compare the safety and effectiveness of image-guided thermal ablation (IGTA) for upper pole versus nonupper pole renal lesions ≤4 cm given the technical challenges of the former.

MATERIALS AND METHODS: This retrospective single-center study (2017-2024) included 115 patients (116 lesions, 41 upper pole and 75 nonupper pole) undergoing IGTA for suspected or confirmed renal cell carcinoma (RCC) ≤4 cm. Overall, 67 lesions were biopsy-confirmed RCCs (22 upper pole and 45 nonupper pole). Lesion characteristics, adverse events (AEs), and oncologic outcomes were analyzed.

RESULTS: Primary effectiveness was 100% (41/41) for upper pole lesions versus 97.3% (73/75) for nonupper pole lesions (P = .54). Grade 3 (severe) AEs occurred in 2.4% (1/41) versus 1.3% (1/75) (P > .99). Median follow-up times were 27.0 months for all patients and 24.4 months for those with biopsy-confirmed RCC. For biopsy-confirmed RCC, local tumor progression rates were 9.1% (2/22) for upper pole lesions versus 0% (0/45) for nonupper pole lesions (P = .10), and distant progression rates were 0% for both groups (P > .99). Median overall survival (OS) was 808 days versus 709 days with 3-year OS rates of 92.9% versus 87.0% (P = .22). Nephrometry scores and polar location showed no association with local progression or AEs. Lesion size was correlated with local progression (P < .01) and Grade 2 or higher AEs (P < .01).

CONCLUSIONS: IGTA for upper pole renal lesions ≤4 cm demonstrated safety and effectiveness comparable to nonupper pole lesions with similar AE rates and oncologic outcomes in this single-center cohort.