Radiofrequency ablation of renal tumours with clinical, radiographical and pathological results

What's known on the subject? and What does the study add? Radiological imaging is heavily relied on for follow up after renal ablative therapy. We show that while this is largely reliable, there are quantifiable false negative and false positive findings. A non-involuting zone of ablation should be considered for multisite-directed core biopsies even in the absence of detectable enhancement. Objective To evaluate our experience with radiofrequency ablation (RFA) for renal masses and to report on clinical, radiological and post-RFA biopsy results. Patients and Methods The study collected clinical, radiological and pathological data from 150 consecutive patients who were treated with RFA of a renal mass between 2002 and 2008 at a tertiary referral centre. Post-ablation biopsies were performed in patients with non-involuting lesions or suspicion of recurrence on imaging. Comparisons were performed using the MannWhitney U-test. Survival was estimated using the KaplanMeier method. Results Renal malignancy was found in 72.1% of patients based on the initial diagnostic biopsy. Median tumour size was 2.6cm, 22.7% of patients had a solitary kidney, and most were central tumours. The mean follow-up period was 40.1 month. There was no recurrence in 96.7% of the entire cohort. Cancer-specific survival for 106 patients with sporadic, localized, biopsy proven renal malignancy was 100% at 38.5 months. Biopsies were obtained in 43 patients for a median of 21 months after RFA. Among 38 patients who had biopsy for non-involuting, non-enhancing zones of ablation, three (7.9%) were positive. Conclusions Short-term cancer-specific survival after RFA remains excellent and most cases are successful based on a combination of imaging and post-ablation biopsies performed almost 2 years after treatment. There were four out of 150 (2.7%) patients who had recurrences with tissue confirmation; one of these patients was detected on imaging and three (2%) were radiologically occult. The absence of enhancement in the setting of non-involuting lesions is not always a guarantee of a successful ablation.