The Genitourinary Pathology Society and International Society of Urological Pathology Joint Expert Consultation Recommendations on intraductal carcinoma of the prostate

Abstract

Conflicting practice recommendations regarding the grading of intraductal carcinoma of the prostate (IDCP) from two leading uropathology societies, the Genitourinary Pathology Society (GUPS) and the International Society of Urological Pathology (ISUP), are confusing for both pathologists and treating clinicians. The objectives of this consultation were to clarify unresolved issues regarding IDCP and atypical intraductal proliferation (AIP) terminology, diagnostic criteria, grading, and management implications, as well as to develop uniform reporting guidelines for IDCP and AIP, endorsed by both societies. A 32‐member expert panel, composed of five core members, 25 expert urological pathologists, and two expert urologists, employed a modified Delphi process consisting of multiple rounds of consultation and voting. These were supplemented by discussions at the 2025 United States and Canadian Academy of Pathologists Annual Meeting to achieve expert consensus (defined as at least 67% agreement). Consensus was reached on several key issues. IDCP was regarded most commonly as reflecting the retrograde spread of invasive prostate cancer (PCa). IDCP diagnosis should be based on the Guo and Epstein criteria, supported by basal cell immunohistochemistry in cases that are difficult to distinguish from invasive PCa. The term AIP should be used only in equivocal proliferations where IDCP is favoured but the criteria are not fully met, and these should be reported as ‘ AIP, suspicious for IDCP ’. In the presence of invasive PCa, IDCP should generally be incorporated into Gleason grading irrespective of Grade Group (GG). However, a significant minority (30%) favoured excluding IDCP from the Gleason score if the invasive component was solely Gleason pattern (GP) 3. Pure IDCP (not associated with invasive PCa) and AIP, suspicious for IDCP, should not be graded. IDCP should not be incorporated in the grading of invasive PCa when it is spatially distinct from invasive PCa. A second opinion from a senior or dedicated GU pathologist and discussion within a multidisciplinary management setting should be considered, in the rare settings of pure IDCP or GP3 + IDCP (formerly GG1 + IDCP scenario). This joint GUPS–ISUP consultation provides unified recommendations for the diagnosis, terminology, grading, and reporting of IDCP and AIP, and will pave the way for the development of future IDCP/AIP WHO guidelines. Their adoption should reduce interobserver variation, facilitate consistent communication with clinicians, and improve patient management.

Affiliated Institutions

• Brigham and Women's Hospital US
• University of Rochester Medical Center US
• Harvard University US
• Royal Prince Alfred Hospital AU
• University of Tennessee Health Science Center US
• University of California, Los Angeles US
• University Health Network CA
• University of Alabama at Birmingham US
• Erasmus MC Cancer Institute NL
• University of Toronto CA
• University of California, Davis US
• Brown University US
• Sunnybrook Health Science Centre CA
• The University of Texas MD Anderson Cancer Center US
• Keck Hospital of USC US
• Barts Health NHS Trust GB
• Icahn School of Medicine at Mount Sinai US
• University of North Carolina at Chapel Hill US
• Princess Margaret Cancer Centre CA
• Cleveland Clinic US
• Massachusetts General Hospital US
• University of Chicago US
• Northwestern University US
• Health Sciences Centre CA
• Qilu Hospital of Shandong University CN
• York Central Hospital CA
• Queen Mary University of London GB
• University Hospital Bonn DE
• Aichi Medical University JP
• The University of Texas Southwestern Medical Center US
• New York University US
• Johns Hopkins University US
• University of California, San Francisco US
• Memorial Sloan Kettering Cancer Center US
• University Hospital of Wales GB

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