What is the recommended follow-up care after ablation of a renal mass?

Follow-up Care After Renal Mass Ablation

The American College of Radiology and American Urological Association recommend CT or MRI with and without IV contrast at 3 and 6 months post-ablation, followed by annual abdominal imaging for 5 years, and annual chest radiography for 5 years to monitor for local recurrence and metastatic disease. 1

Imaging Protocol

Initial Follow-up (First Year)

• CT or MRI with and without IV contrast at:
  • 3 months post-ablation
  • 6 months post-ablation
• Corticomedullary phase imaging is critical as it shows the highest sensitivity for detecting local tumor progression 2
• Note: Excretory phase images are not necessary for detecting recurrence 2

Long-term Follow-up

• Annual abdominal imaging (CT or MRI) with and without IV contrast for 5 years 1
• Annual chest radiography for 5 years to monitor for pulmonary metastases 1
• Imaging beyond 5 years is optional based on individual risk factors:
  • Biopsy-proven renal cell carcinoma
  • Previous incomplete ablation
  • History of treatment failure 1

Treatment Success Criteria

Successful ablation is characterized by:

• Lack of contrast enhancement (<10-20 Hounsfield units on CT) 1
• Progressive involution of the ablated mass over time 1

Signs of treatment failure include:

• Visually enlarging neoplasm
• New nodularity in the treatment area
• Enhancement of the neoplasm on post-treatment contrast imaging
• Failure of regression in size of the treated lesion over time 1

Follow-up Based on Pre-treatment Biopsy Results

Patients with Confirmed Benign Histology

• No further imaging required after the 6-month follow-up if treatment success is radiographically confirmed 1

Patients without Biopsy or with Indeterminate Results

• Follow as if they have renal cell carcinoma with the full imaging protocol 1

Clinical Follow-up

• Annual history and physical examination focusing on:
  • Signs and symptoms of local recurrence
  • Metastatic disease
  • Renal function 1
• Laboratory testing:
  • Blood urea nitrogen (BUN)/creatinine
  • Urinalysis
  • Estimated glomerular filtration rate (eGFR) 1

Important Considerations and Pitfalls

1. Non-involuting lesions require biopsy: Even in the absence of enhancement, non-involuting zones of ablation should undergo biopsy, as studies have shown up to 7.9% of non-enhancing, non-involuting lesions can harbor viable tumor cells 3

2. Extended follow-up importance: Delayed recurrence is possible, with studies showing recurrences occurring as late as 31 months post-ablation, particularly for tumors >3.0 cm and centrally located 4

3. False negatives in imaging: The absence of enhancement does not always guarantee successful ablation, especially in non-involuting lesions 3

4. Contrast-enhanced sonography: While not part of the standard guidelines, contrast-enhanced sonography has shown high concordance with CT/MRI for hypervascular tumors (96.4% accuracy) and may be considered as a supplementary follow-up tool 5

5. Repeat ablation considerations: For patients with incomplete ablation or recurrence, repeat RFA has shown good success rates, with studies demonstrating successful retreatment in patients requiring second sessions 4

6. Biopsy timing: If treatment failure is suspected, repeat biopsy should be performed within 6 months if the patient is a treatment candidate 1

7. Avoid chest CT for routine surveillance: Chest radiography is preferred over chest CT for routine surveillance due to potential false positives with CT 1

8. Pre-treatment biopsy importance: Obtaining pre-treatment biopsy prevents unnecessary intense surveillance for patients with benign tumors 1