Follow-up Protocol after Cryoablation of a Renal Mass

Imaging Follow-up

The American College of Radiology and the American Urological Association recommend CT or MRI with and without IV contrast at 3 and 6 months post-cryoablation to assess treatment success, with annual abdominal imaging (CT or MRI) with and without IV contrast for 5 years to monitor for local recurrence and metastatic disease 1, 2, 3
Annual chest radiography for 5 years is recommended to monitor for pulmonary metastases, while chest CT is generally not recommended for routine surveillance due to potential false positives 1, 2
Imaging beyond 5 years is optional based on individual patient risk factors, such as biopsy-proven renal cell carcinoma, previous incomplete ablation, or history of treatment failure 2

Lack of contrast enhancement (<10-20 Hounsfield units on CT) is considered the hallmark of successful treatment, according to the American College of Radiology and the American Urological Association 1, 2
Treatment failure or local recurrence should be suspected with visually enlarging neoplasm, new nodularity in the treatment area, enhancement of the neoplasm on post-treatment contrast imaging, or failure of regression in size of the treated lesion over time 1, 2
Indicators of treatment failure include failure of treated lesion to regress in size, development of new areas of enhancement in treatment zone, and progressive increase in size of ablated mass 2, 1

Patients with pathological confirmation of benign histology before treatment who show radiographic confirmation of treatment success require no further imaging after the 6-month follow-up, as recommended by the American Urological Association 2
Patients without a biopsy or with indeterminate results should be followed as if they have renal cell carcinoma, according to the American Urological Association 2
Annual history and physical examination focused on detecting signs and symptoms of local recurrence, metastatic disease, and renal function is recommended, along with basic laboratory testing including blood urea nitrogen (BUN)/creatinine, urinalysis, and estimated glomerular filtration rate (eGFR) 2

Neglecting to obtain pre-treatment biopsy can lead to unnecessary intense surveillance in patients with benign tumor histology, according to the American Urological Association 2
Relying solely on enhancement patterns immediately post-ablation can lead to false positives, as enhancement may persist for several months even in successfully treated lesions, according to the American College of Radiology 1
Using chest CT for routine surveillance can lead to potential false positives (intrapulmonary lymph nodes and granulomas), according to the American College of Radiology 1
New enhancement, progressive increase in size of the ablated area, or new nodularity in or around the treated zone should prompt a repeat lesion biopsy, and neglecting renal function can lead to progressive renal insufficiency, which should prompt nephrology referral 2
If treatment failure is suspected, repeat biopsy should be performed if there is radiographic evidence of treatment failure within 6 months and the patient is a treatment candidate, to confirm recurrence or progression, and discussion of alternatives, including observation, repeat ablation, or surgical intervention, is recommended 2