Intraductal carcinoma has a minimal impact on Grade Group assignment in prostate cancer biopsy and radical prostatectomy specimens

Abstract

Intraductal carcinoma has a minimal impact on Grade Group assignment in prostate cancer biopsy and radical prostatectomy specimens Aims: Intraductal carcinoma (IDC) is an adverse histopathological parameter for prostate cancer outcome, but is not incorporated in current tumour grading. To account for its dismal prognosis and to omit basal cell immunohistochemistry, it has been proposed to grade IDC on the basis of its underlying architectural pattern. The aim of this study was to determine the impact of IDC grade assignment on prostate cancer biopsy and radical prostatectomy tumour grading. Methods and results: A cohort of 1031 prostate cancer biopsies and 835 radical prostatectomies were assigned a Grade Group according to the 2014 International Society of Urological Pathology guidelines, without incorporation of IDC in grading. Tumour grading was compared with a Grade Group in which IDC was graded on the basis of its underlying architecture. Of 1031 biopsies, 139 (13.5%) showed IDC. Grade assignment of IDC led to a Grade Group change in 17 (1.6%) cases: four of 486 (0.8%) Grade Group 1 cases were reclassified as Grade Group 2, nine of 375 (2.4%) Grade Group 2 cases were reclassified as Grade Group 3, and four of 58 (6.9%) Grade Group 4 cases were reclassified as Grade Group 5. IDC was observed in 213 of 835 (25.5%) radical prostatectomies, and its grading led to a change in tumour grade in five of 835 (0.6%) patients, with upgrading in two of 207 (1.0%) patients with Grade Group 1 cancer, in two of 420 (0.5%) patients with Grade Group 2 cancer, and in one of 50 (2%) patients with Grade Group 4 cancer. Conclusion: IDC grade assignment led to a Grade Group change in 1.6% of prostate biopsy specimens and in 0.6% of radical prostatectomy specimens. Although the inclusion of IDC in or the exclusion of IDC from the Grade Group might affect decision-making in individual patients, it has a minimal impact on overall prostate cancer management.

Prostate cancer growth patterns beyond the Gleason score: entering a new era of comprehensive tumour grading

“…27 Inclusion or exclusion of IDC in tumour grading results in a global Grade Group shift in < 2% of prostate cancer biopsies. 28,29…”

“…Both the ISUP and the GUPS recommend including a comment on the association of IDC with aggressive disease, whereas the vast majority of genitourinary pathologists consider the above‐mentioned case not to be eligible for active surveillance 27 . Inclusion or exclusion of IDC in tumour grading results in a global Grade Group shift in < 2% of prostate cancer biopsies 28,29 …”

Contemporary Grading of Prostate Cancer: The Impact of Grading Criteria and the Significance of the Amount of Intraductal Carcinoma

“…Assessment of IDC was performed on H&E slides using the criteria established by Guo and Epstein [16] minus the size criterion [14]. Presence of basal cells, corpora amylacea and branched architecture were used as criteria to differentiate IDC from invasive cribriform pattern [35]. Immunohistochemistry for basal cell markers was not performed, unless it had been requested by the diagnosing pathologist when signing out the cases, to mimic routine practice [36].…”

Grading Intraductal Carcinoma in Prostate Biopsies Changes Risk Categorization in a Small Subset of Cases

“…To the Editor.-Lately, there has been debate as to whether intraductal carcinoma of the prostate (IDC) should be graded or not when it is present with concurrent invasive carcinoma, resulting in conflicting recommendations put forth by the International Society of Urological Pathology and the Genitourinary Pathology Society. 1,2 Two recent studies 3,4 have shown that grading IDC in prostate biopsies might result in Grade Group (GG) changes in~2% to 23% of cases. However, the impact of grading IDC on risk stratification of patients with prostate cancer (PCa) is somewhat unclear.…”