Genitourinary Pathology Society and International Society of Urological Pathology White Paper on Defining Indolent Prostate Cancer.

A significant subset of well-differentiated prostatic acinar neoplasms with invasive histologic features will not spread outside of the prostate, become symptomatic, or shorten a patient's life even if the tumor is left untreated. Overdiagnosis and overtreatment of these indolent prostate cancers (PCa) remain a significant health care problem despite the improved risk assessment and uptake in acceptance of conservative management. While detection of indolent PCa on an entirely resected prostate is possible, recognition of indolent PCa on a needle biopsy (NBX) cannot be reliably made as Grade Group 1 (GG1) PCa diagnosis on NBX is not always identical to one from radical prostatectomy due to a variety of reasons. Further, some of the initially diagnosed GG1 PCas on NBX and carefully monitored on active surveillance (AS) are later reclassified with higher grades. At the same time, other GG1 PCas never progressed on long-term follow-up while receiving no therapy. The overarching goal of this white paper by the 2 leading uropathology organizations, Genitourinary Pathology Society (GUPS) and International Society of Urological Pathology (ISUP), is to help identify a path toward a more meaningful multidisciplinary solution addressing the pervasive problem of overdiagnosis of indolent PCa and its downstream negative effects. Herein, GUPS and ISUP jointly release statements that address why recognition of indolent PCa cannot be reliably made in NBX and why various contemporary multidisciplinary approaches are needed to help improve the detection of indolent PCa in NBX.