Diagnosis of prostate cancer on needle biopsy: Current practices Medical College of Georgia 12/07/2006 Jeremy S. Miller, MD

Current practice of diagnosis and reporting of prostate cancer on needle biopsy among genitourinary pathologists Lars Egevad MD, William C. Allsbrook Jr. MD, and Jonathan I. Epstein MD Karolinska Hospital, Stockholm, Sweden Medical College of Georgia, Augusta, Georgia Johns Hopkins Hospital, Baltimore, Maryland Human Pathology (November 2006) Volume 37,

Why is this important?  Authors cited a ‘lack of hard data in the literature’ about many of the issues regarding diagnosing and reporting prostate cancer  They sought to survey current practices in order to provide a consistent guideline for the general pathologist  Questionnaire was sent to 93 genitourinary pathologists with a response rate of 69%

Introduction  Core needle biopsies of the prostate are now among the most common specimens received at pathology laboratories  Laboratory techniques for the diagnosis of prostate cancer have developed rapidly; it is unknown to what extent new developments have been adopted by pathologists  Criteria for diagnosis (including new morphologic variants) have not been consistently developed  Reporting parameters (e.g. extent of cancer, perineural invasion) have not been consistently adopted into all pathology reports

Materials and methods  Questionnaire distributed to 93 GU pathologists in 20 countries worldwide: Demographic, age, nationality, type of practice Demographic, age, nationality, type of practice Normal lab routines pertaining to handling and processing prostate needle biopsies Normal lab routines pertaining to handling and processing prostate needle biopsies How prostate cancer is diagnosed and reported How prostate cancer is diagnosed and reported Most questions were ‘fixed response’ Most questions were ‘fixed response’

Results - demographics  Overall response rate 64/93 (69%)  Location USA37 USA37 Canada3 Canada3 Europe15 Europe15 Asia4 Asia4 South America2 South America2 Australia/ New Zealand3 Australia/ New Zealand3  Work environment Academic Institution43 Academic Institution43 Private health care (or mixed academic/ private)17 Private health care (or mixed academic/ private)17 Military or non-academic community health care4 Military or non-academic community health care4  Age >701 >701

Results - processing  Routine fixative Formalin94% Formalin94% Bouin’s solution3% Bouin’s solution3% Zn-formalin2% Zn-formalin2% Alcohol or Hollande’s solution0% Alcohol or Hollande’s solution0%  Number of H+E levels Mean3.1 Mean3.1 Median3 Median3 Range1-12 Range1-12  Unstained sections on intervening levels between H+E slides Routine47% Routine47%  Immunohistochemical stains used to diagnose cancer in uncertain cases HMWK (34βE12)91% HMWK (34βE12)91% P6358% P6358% CK 5/69% CK 5/69% Other cytokeratin2% Other cytokeratin2% AMACR (p504s)50% AMACR (p504s)50% None2% None2%  Histochemical stains used to diagnose cancer in uncertain cases None98% None98% Mucin2% Mucin2%

Circumferential perineural invasion

Glomeruloid bodies (glomerulations)

Collagenous micronodules (mucinous fibroplasia)

Results – diagnostic criteria  Pathognomonic for prostate cancer: Circumferential perineural invasion84% Circumferential perineural invasion84% Collagenous micronodules (mucinous fibroplasia)64% Collagenous micronodules (mucinous fibroplasia)64% Glomeruloid bodies (glomerulations)58% Glomeruloid bodies (glomerulations)58% Glands in adipose tissue36% Glands in adipose tissue36% If none of the above, require a minimum number of glands If none of the above, require a minimum number of glands Pathologist older than 50 years47%Pathologist older than 50 years47% Pathologist younger than 50 years27%Pathologist younger than 50 years27%  Number of glands required for diagnosis Mean2.1Mean2.1 Median1Median1 Range1-10Range1-10  Patient age influences diagnosis Yes17%Yes17% Liberal approach if patient > 70 y/o6%Liberal approach if patient > 70 y/o6% Conservative approach if patient < 60 y/o8%Conservative approach if patient < 60 y/o8%

Focal prostatic adenocarcinoma, 3+3=6

Results – Gleason grading  When diagnosing cancer on a small group of atypical, non- cribriform glands (< 3 mm) Gleason score 45% Gleason score 45% Gleason score 53% Gleason score 53% Gleason score 677% Gleason score 677% Gleason pattern but no score5% Gleason pattern but no score5% No Gleason score or pattern9% No Gleason score or pattern9%  Include note stating that grade may not be accurate due to sampling error Yes14% Yes14% No86% No86%  Include note stating that cancer may be clinically ‘insignificant’ Yes23% Yes23% No77% No77%

Results - other  Report perineural invasion routinely86%  Extent of cancer quantified100% Number of involved cores80% Number of involved cores80% Percentage of cancer per core53% Percentage of cancer per core53% Overall percentage of cancer per case41% Overall percentage of cancer per case41% Millimeters of cancer per core39% Millimeters of cancer per core39% Overall millimeters of cancer per case8% Overall millimeters of cancer per case8% Subjective measure8% Subjective measure8% i.e. minute, focal, moderate, extensivei.e. minute, focal, moderate, extensive Measure cancer ‘end-to-end’34% Measure cancer ‘end-to-end’34% Regardless of intervening benign tissueRegardless of intervening benign tissue Subtract intervening benign tissue39% Subtract intervening benign tissue39%

‘End-to-end’ – 34% Subtract intervening benign tissue – 39% 80% of core 20% of core

Discussion  Bouin’s and Hollande’s solutions have been proposed as alternatives to formalin for superior nuclear preservation The survey shows that formalin remains the predominant fixative The survey shows that formalin remains the predominant fixative Possible reasons: Possible reasons: Both Bouin’s and Hollande’s solutions contain picric acid, which is toxic and potentially explosiveBoth Bouin’s and Hollande’s solutions contain picric acid, which is toxic and potentially explosive Diagnostic criteria and literature illustrations are based on formalin-fixed specimensDiagnostic criteria and literature illustrations are based on formalin-fixed specimens

Discussion  HMWK stains basal cell cytoplasm; p63 stains basal cell nuclei; AMACR stains prostate cancer cells HMWK retains leading role as predominant IHC marker (91%), while p63 is used by 58% HMWK retains leading role as predominant IHC marker (91%), while p63 is used by 58% Despite initial enthusiasm for AMACR, only 50% of respondents are routinely using it Despite initial enthusiasm for AMACR, only 50% of respondents are routinely using it A possible reason is lack of specificity for prostate cancerA possible reason is lack of specificity for prostate cancer

Discussion  Routinely cutting unstained sections between H+E levels is twice as common in North America than elsewhere While most pathologists stated a preference for this, some cited economic resources as a reason for not doing so routinely While most pathologists stated a preference for this, some cited economic resources as a reason for not doing so routinely  These sections were critical for diagnosis in 2.8%* * Green, R, Epstein JI. Use of intervening unstained slides for immunohistochemical stains for high molecular weight cytokeratin on prostate needle biopsies. Am J Surg Pathol 1999;23;567-70

Discussion  Glomeruloid bodies and mucinous fibroplasia Relatively uncommon in needle biopsies Relatively uncommon in needle biopsies Have been claimed to be pathognomonic for cancer* Have been claimed to be pathognomonic for cancer* Only 58% and 64% use these as cancer-specific Only 58% and 64% use these as cancer-specific  Circumferential perineural invasion Diagnostic utility is limited: Extremely low incidence in limited cancer Diagnostic utility is limited: Extremely low incidence in limited cancer Used by 84% as cancer specific Used by 84% as cancer specific Benign glands in perineural spaces have been described Benign glands in perineural spaces have been described  Glands involving adipose tissue Usually means extraprostatic extension Usually means extraprostatic extension Rarely, fat is seen in prostate in the absence of cancer** Rarely, fat is seen in prostate in the absence of cancer** Possibly due to this, only 36% considered this pathognomonic for cancer Possibly due to this, only 36% considered this pathognomonic for cancer * Baisden BL, Kahane H, Epstein JI. Perineural invasion, mucinous fibroplasia, and glomerulations: diagnostic features of limited cancer on prostate needle biopsy. Am J Surg Pathol 1999;23; ** Cohen, RJ, Stables S. Intraprostatic fat. Hum Pathol 1998;29;424-5

Discussion  Number of malignant glands required for diagnosis 61% would occasionally diagnose cancer on a single atypical gland 61% would occasionally diagnose cancer on a single atypical gland Mean number required to diagnose was 2.1 Mean number required to diagnose was 2.1 At consensus conference in 1999, 3 glands were an agreed requirement At consensus conference in 1999, 3 glands were an agreed requirement The number is coming down, most likely due to the increasing usefulness of immunohistochemistry and pathologists’ comfort with the morphology of limited cancer The number is coming down, most likely due to the increasing usefulness of immunohistochemistry and pathologists’ comfort with the morphology of limited cancer A caveat – “…low figures given in the survey responses may reflect unusual cases with a very pronounced architectural distortion or severe nuclear atypia.” A caveat – “…low figures given in the survey responses may reflect unusual cases with a very pronounced architectural distortion or severe nuclear atypia.”

Discussion  Prognostic factors from core needle biopsies, according to CAP 1. Gleason score 1. Gleason score 2. Amount of cancer 2. Amount of cancer 3. Perineural invasion 3. Perineural invasion  Only 86% currently assign a Gleason score to a small focus of cancer  It has been demonstrated that biopsy Gleason score in such a case correlates almost as well with prostatectomy grade as when there is more extensive core involvement*  Current recommendations are to use Gleason score 6 for a small focus of non-cribriform cancer 77% currently do so 77% currently do so 8% preferred to use a lower score 8% preferred to use a lower score  Several consensus documents recommend reporting of perineural invasion 86% follow this recommendation 86% follow this recommendation * Rubin MA, Dunn R, Kambham N, Misick CP, O’Toole KM. Should a Gleason score be assigned to a minute focus of carcinoma on prostate biopsy? Am J Surg Pathol 2000;24;

Discussion  2004 WHO-sponsored International Consultation on Prognostic Factors in Prostate Cancer recommended that the pathology report should contain: Number of involved cores Number of involved cores At least one measure of linear extent (millimeters or percent; individual or global) At least one measure of linear extent (millimeters or percent; individual or global)  100% of respondents do so 80% use percentage 80% use percentage 41% use millimeters 41% use millimeters 22% use both 22% use both  No consensus among survey respondents on the technique for measuring linear extent ‘End-to-end’ (34%) vs. subtracting intervening benign tissue (39%) ‘End-to-end’ (34%) vs. subtracting intervening benign tissue (39%) This discrepancy warrants further study This discrepancy warrants further study

Summary  Good agreement Formalin for fixative Formalin for fixative Three levels generated for H+E stains Three levels generated for H+E stains Use of basal cell markers Use of basal cell markers Circumferential perineural invasion as a pathognomonic feature of cancer Circumferential perineural invasion as a pathognomonic feature of cancer Lack of relevance of patient’s age when diagnosing cancer Lack of relevance of patient’s age when diagnosing cancer Routine reporting of perineural invasion and Gleason score even in small cancer foci Routine reporting of perineural invasion and Gleason score even in small cancer foci  Further standardization needed Which immunohistochemical stains to diagnose cancer Which immunohistochemical stains to diagnose cancer Minimum number of atypical glands required for cancer diagnosis Minimum number of atypical glands required for cancer diagnosis Optimal methods for assessment of linear extent of prostate cancer in core biopsies Optimal methods for assessment of linear extent of prostate cancer in core biopsies