732 - Post–Renal Cryoablation Follow-up: A Standardized Approach

Learning Objectives: • Use evidence-based medicine to develop a systematic approach for monitoring patients after cryoablation of renal masses
• Have a reference timeline for the management of post renal cryoablation patients
• Identify the signs to detect residual unablated tumor early in order to retreat promptly

Background: Renal Cryoablation (RCYA) is a widely accepted, safe and efficacious treatment for small renal masses (< 4 cm) with increasing evidence to suggest it can be considered for a broader patient population (up to 7 cm) {1}. Unfortunately, with local tumor progression rates of 4% {2}, post procedural management is crucial in addressing technical failure, local tumor progression, and metastatic disease. With a standardized post-RCYA protocol, clinical interventionalists can detect progression earlier, avoid unnecessary imaging, and reduce the number of patients lost to follow up.

Clinical Findings/Procedure Details: Post-RCYA Standardized Schedule

1 month (±2 weeks)
Follow up in IR clinic with standardized H&P and contrast-enhanced CT (CECT) Abdomen Renal Protocol to evaluate for early adverse events (e.g. seroma, hematoma) along with labs (Cr, eGFR, and CBC/CMP) to evaluate renal function. Consider MRI for younger patients and impaired renal function. If equivocal at 1 month, obtain an early repeat scan (e.g., at 6–8 weeks)

3 months
IR clinic visit with H&P and labs as above. CECT or MRI abdomen for focused evaluation on progression of disease. This is a key efficacy check and aligns with major guideline timing which suggests >50% of residual unablated tumor are evident by 1 month
and approximately 70% by 3 months.

6 months
IR clinic visit and labs. CECT or MRI abdomen. Confirm non-enhancing stable treatment zone in order to transition to annual imaging.

Annual monitoring years 1-5
IR clinic visit and labs. CECT or MRI abdomen yearly to 5 years. CT chest without contrast if higher suspicion/at clinician discretion. Continued surveillance beyond year 5 is based on shared decision-making, many centers extend to 7–10 years.

Conclusion and/or Teaching Points: A clear follow up plan for RCYA is imperative to identify technical failure, progression, and increase patient adherence. A successful ablation will lack measurable enhancement in the ablation zone (increase < 10-20 HU on post-contrast CT) with progressive involution, although transient early enhancement can occur. Persistent, nodular, or increasing enhancement at the margin on early surveillance (often apparent by 1-3 months) may require prompt re-ablation. Pre-ablation biopsy is strongly encouraged to confirm malignancy if imaging is atypical.