EAU 2019: MUSIC-KIDNEY Collaborative Assesses Patterns of Renal Mass Biopsy

Barcelona, Spain (UroToday.com) Renal tumor biopsy (RTB) for renal cell carcinoma (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. 

In this abstract by the Michigan Urological Surgery Improvement Collaborative (MUSIC), which is a large multi-institutional data sharing program among Michigan urology programs in an effort to improve statewide urologic care – it is a unique program that provides great insight into a large mixed practice community. Previously focused on prostate cancer primarily, they have now expanded to other fields, including kidney (focusing on masses <= 7cm, cT1 lesions) and stones. 

This is a pilot study of the MUSIC-KIDNEY program to assess utilization of RTB in newly diagnosed cT1 renal lesions within this large Michigan Urology community. Data collection started in September 2017 at 8 practices; data is input by designated paid abstractors. Data was input for all patients at a single time point 3 months (120 days) after the initial presentation – an allowance for one additional data extraction 3 months later was allowed if a final treatment plan had not been made yet. Management was separated as AS, RTB, or active treatment, as well as details regarding the follow-up plan.

581 patients with renal masses ≤7cm were identified and included, and of these, only 71 (12.2%) underwent a RTB. 

At an institutional level, as with prostate cancer management, there was significant variability - RTB utilization across the 8 sites ranged from 0-23% (median 11%), with 11% of RTB performed by a urologist. 

When comparing patients who did or did not have an RTB, no statistical differences in patient and tumor characteristics were observed between those having or not having RMB (Table 1 below):


  • 60% of RTB were performed for masses 1-3 cm; None for mass < 1 cm
  • 97% of the RTB procedures were same-day procedure, with discharge home after the procedure
Use of RTB based on tumor size is below:


As for complication, 2 patients (2.8%) were evaluated in the emergency department (with 1 hospitalization) following RTB. 

With regards to RTB outcomes, the non-diagnostic rate of RMB across the collaborative was only 5.6% (n=4); the remaining RTB were categorized as benign (n=16, 22.5%), favor malignancy (n=4, 5.6%), or malignant (n=47, 66.2%). This nondiagnostic rate is significantly lower than other series, even at centers of excellence.

Patients with a benign biopsy were more likely to be surveilled then patients managed without RTB (81% vs 48%, p=0.009) – which makes sense, as there is now pathology suggesting a benign tumor. The benign histology rate at surgery in RTB naïve patients was 13.1% vs 3.03% with RTB (p=0.09) – these represent the patients that could have been spared surgery if they had been biopsied ahead of time. Importantly, 15 patients (25%) with malignancy at RMB were still surveilled – as greater knowledge of the indolent natural history of RCC becomes known, AS may become a more utilized approach for small RCCs with a low grade.

The full breakdown of RTB utilization, pathology outcomes, and management is seen below:


  • 4-13% of patients undergoing treatment, regardless of prior RTB, had benign final pathology
  • 201 cT1 and 40 cT1b masses without RTB were put on AS – which is a great sign that AS is increasingly being utilized
This is another great effort by the MUSIC collaborative. Their main conclusions were that there is significant variability in the utilization of RTB in the community practice. A favorable non-diagnostic rate was noted compared to the literature, and only 3% of patients in the RMB cohort had benign histology at surgical intervention as compared to 13% with no prior biopsy. T low overall use of RTB across the MUSIC-KIDNEY practices is concerning - and increased utilization could reduce the number of surgeries for benign RM≤7cm.

Presented by: Anita K. Patel, MD, Internal Medicine, Nephrology, Transplant Surgery, Henry Ford Hospital, Detroit, Michigan, United States

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