EAU 2019: Pre-ablative or Peri-ablative Biopsies: A Comparison of Different Diagnostic Strategies in Small Renal Masses Treated with Ablation

Barcelona, Spain (UroToday.com) Renal tumor biopsy (RTB) for RCC, especially for small renal masses, is recommended by international guidelines if the RTB pathology will change treatment management – either favoring surveillance or ablative therapy. Yet, its usage remains relatively low and uptake is sporadic. Its accuracy is reported to be quite high in more recent series but can be very institutional dependent. More important, with regards to focal ablative therapy, RTB can either be done at a separate setting from the actual treatment or at the time of treatment itself.

In this study, authors complete a local multi-institutional retrospective assessment of their RTB biopsy diagnostic accuracy, correlated to when the biopsy is done relative to tumor ablation. They only looked at patients with cT1 tumor who went on to receive cryotherapy, radiofrequency ablation, or microwave ablation between 2007 and 2017. All biopsies were performed under CT, MRI or US guidance.

An important limitation is that they only looked at patients who underwent tumor ablation – so patients who had a pre-procedure biopsy, but didn’t end up getting ablation were not included (either due to more radical therapy or no therapy).

They identified a total of 641 patients with a median tumor size of 2.9 cm. The majority (69%) had RTB performed at the time of ablation, and 10% of patients had no ablation at all. 

When looking at the pathologic outcomes of the biopsy, they limited it to patients who only had a pre-op or peri-op biopsy (excluding patients with no biopsy or biopsy at both settings).

Peri-op biopsies captured significantly more benign masses and less malignancy. However, the sample size is quite small, so differences may not be captured well. Grossly, peri-op biopsy results in high detection of benign pathology and non-diagnostic biopsy – likely due to the limitation previously discussed.

Based on these results, the authors suggest that peri-op biopsy may lead to overtreatment of benign masses, and as a result, the authors suggest that pre-op biopsy should be favored – in order to make a decision regarding need to treat.

Presented by: C.V. Widdershoven, Antoni van Leeuwenhoek, Department of Urology, Amsterdam, The Netherlands

Written by: Thenappan Chandrasekar, MD (Clinical Instructor, Thomas Jefferson University) (twitter: @tchandra_uromd, @TjuUrology) at the 34th European Association of Urology (EAU 2019) #EAU19 conference in Barcelona, Spain, March 15-19, 2019. 
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