Washington, DC (UroToday.com): The role of renal mass biopsy in the management of small renal masses (SRM; defined as a cT1a mass) is increasing as the movement towards active surveillance of benign masses or indolent cancers increases. Stuart Wolf, Jr., MD, from University of Michigan presented data from his institution on a large cohort of patients with SRMs. He set out to answer four questions. The first question was whether renal mass biopsy (RMB) can
identify patients for active surveillance (AS). He highlighted their 2013 paper which broke down patients into groups based on RMB result and tumor size. Benign masses were enrolled in active surveillance, and those with cancer grade ≥3 were treated. All other SRMs were labeled intermediate masses and these were stratified by grade, histologic type, and size (cut off 2 cm). To determine whether RMB was a viable strategy to enroll patients in AS, they reviewed 133 patients who had biopsy and surgery. Only 4/133 patients had the incorrect assignment for a 14% false negative rate. Because there was concern that size was driving the algorithm, his group performed a though experiment based on biopsy to show that 9/31 patients with tumors <2 cm would have been placed on AS inappropriately if size was the only characteristic used to assign therapy. Interestingly, adding R.E.N.A.L. nephrometry score did not improve the accuracy of the algorithm. The second question he aimed to answer was what happens to false negative patients, those who are assigned to AS based on an incorrect pathologic diagnosis. To answer this question, he compared two groups of patients: those treated immediately and those treated after a period of active surveillance. In comparing these two populations, there was no difference in the rate of nephron-sparing or upgrading, allowing him to conclude that a delay in treatment that results from falsely negative biopsy or incorrect risk grouping probably does not lead to a longer-term harm. The third question he addressed was whether or not RMB actually informs treatment decisions. His group evaluated initial treatment decisions on 366 patients who had RMB and showed that almost all of them had the treatment that the biopsy algorithm would assign. The last question he set out to answer was whether or not RMB ensures adherence to active surveillance long term. He compared patients on AS who had prior RMB to patients on AS who did not have prior RMB. As has been shown previously, size >2 cm and increased growth rate were associated with delayed treatment, but prior RMB did not associate with adherence to AS. He concluded by mentioning a genomic signature that he and his collaborators have developed which is under embargo until 2016 which associates with long-term outcomes.
Stuart Wolf, Jr, MD
University of Michigan
Mohammed Haseebuddin, MD. from the Society of Urologic Oncology Meeting - December 2 - 4, 2015 – Washington, DC.
Fox Chase Cancer Center, Philadelphia, PA.