Practice Patterns in Reporting Tertiary Grades at Radical Prostatectomy: Survey of a Large Group of Experienced Urologic Pathologists.

Context.—: In prostate cancer, "tertiary" higher-grade patterns (TPs) have been associated with biochemical recurrence after radical prostatectomy.
Objective.—: To determine variation regarding definition and application of TPs.
Design.—: Online survey regarding TPs in a range of grading scenarios circulated to 105 experienced urologic pathologists.
Results.—: Among 95 respondents, 40 of 95 (42%) defined TPs as "third most common pattern" and 55 (58%) as "minor pattern/less than 5% of tumor." In a tumor with pattern 3 and less than 5% pattern 4, of the 95 respondents, 35 (37%) assigned 3 + 3 = 6 with TP4, while 56 (59%) assigned 3 + 4 = 7. In a tumor with pattern 4 and less than 5% pattern 5, of the 95 respondents, 51 (54%) assigned 4 + 4 = 8 with TP5, while 43 (45%) assigned 4 + 5 = 9. Six scenarios were presented in which the order of most common patterns was 3, 4, and 5 (Group 1) or 4, 3, and 5 (Group 2) with varying percentages. In both groups, when pattern 5 was less than 5%, we found that 98% and 93% of respondents would assign 3 + 4 = 7 or 4 + 3 = 7 with TP5. In scenarios with 15% or 25% pattern 5, most respondents (70% and 80%, respectively) would include pattern 5 as the secondary grade, that is, 3 + 5 = 8 (Group 1) or 4 + 5 = 9 (Group 2). For 85 of 95 (89%), a TP would not impact Grade Group assignment.
Conclusions.—: This survey highlights substantial variation in practice patterns regarding definition and application of "tertiary" grading in radical prostatectomy specimens. High consistency was observed in 3 + 4 = 7/4 + 3 = 7 scenarios with truly minor pattern 5. These findings should inform future studies assessing the standardization and predictive value of "tertiary" patterns.