AUA 2018: Pretreatment Diagnosis of the Small Renal Mass: Status of Renal Biopsy in the US

San Francisco, CA ( Renal tumor biopsy is now recognized as a safe procedure with limited risks compared to historical series. The theoretical risk of seeding has not been seen in more recent series. Improved biopsy technique has improved yield. However, uptake has been limited by the general medical community and is often reserved for patients who active surveillance is considered, especially in patients who are not good surgical candidates.

In this study, the authors attempt to get a sense of the current impressions of RTB utility in the management of renal masses by surveying all members of the American Urological Association using an 11-question web-based survey over a 2 month period (December 2016 to January 2017). Naturally, web based surveys, while reaching a large audience, have inherent biases – people who respond often feel strongly about the issue; response rates amongst physicians are usually quite poor; and surveys done over a short time likely don’t represent the entire population.

Unfortunately, the actual survey questions were not provided. All were closed ended, multiple choice questions. 

However, among 6,731 surveys circulated, they received 1,131 responses (17% of the population). Per their knowledge of the respondents, the authors note that they equally represented all regions of the U.S.A (23-29% in each of 4 regions). Most were fully practicing urologists (98%) rather than trainees. Yet, the majority were in private practice (64%) and only 25% represented academic practice. Importantly, however, 47% responded that they treat 20+ cases of renal masses per year – though, the nature of this management is uncertain.

In terms of results, 32% of American urologists practicing in 2017, would ″never″ perform a biopsy of a renal mass ≤4cm. Urologists who practiced at an academic hospital were more likely to perform a renal biopsy on both a renal mass ≤4cm and a renal mass 2-3cm compared to private practitioners and government-based urologists (p<0.001 and p=0.008 respectively). 

Urologists who saw < 5 SRM per year were more likely to ″never″ perform a renal biopsy on either a renal mass ≤4cm or a renal mass 2-3cm compared to those who saw > 5 small renal masses per year (p<0.001). Higher volume Urologists likely dealth with more complex cases requiring pathology for management decisions.

Respondents ranked reasons not to perform a biopsy. The most common reason (68%) was that they felt it would not change their management. Other reasons included: risk of false negative (10%), risk of nondiagnostic biopsy (10%), and risk of complications (~5%), risk of seeding (~5%), and lack of infrastructe (~5%). Urologists independently performed only 2% of biopsies; 48% of urologists stated that they would be interested in learning how to do office-based ultrasound-guided biopsy of a SRM.

In my discussion with the authors, they have done about 75 in-office ultrasound guided biopsies using EMLA topical anesthetic. Their diagnostic yield on 1st biopsy is ~80% and 90% with a second biopsy.

These results are concordant with results from a Canadian survey (presented at CUA 2017). In general, at most centers, RTB is done by interventional radiologists – but the finding of interest amongst urologists to do their own RTB under US guidance is very interesting! Perhaps it is something that would be better adapted if it was taught in residency training?

Naturally, these results should be taken with a grain of salt due to the nature of web-based surveys. However, the results demonstrate the work that exists to help increase the utility and understanding of RTB.

Presented by: Roshan Patel, UC Irvine, Orange County, California
Co-Author: Shoaib Safiullah, Zhamshid Okhunov, Kamaljot Kaler, Kathryn Osann, Jaime Landman, Ralph Clayman

Written by: Thenappan Chandrasekar, MD, Clinical Fellow, University of Toronto, @tchandra_uromd at the 2018 AUA Annual Meeting - May 18 - 21, 2018 – San Francisco, CA USA