Gleason Stereotypes

Presence of perineural invasion is the category III prognostic variable and is associated with increased incidence of extraprostatic extension and aggressive phenotypes.21Data varies across studies with a maximum percentage of about 90% in a study conducted by Merrilees AD et al 84and minimum of 16% and 17% in studies conducted by Nelson et al82 & Quinn et al83 respectively. In present study,38% of CaPs showed perineural invasion. Studies having more number of well differentiated tumors have low percentages of evidence of PNI while studies with more number of high grade tumors have high percentages of evidence of PNI. We had 39 cases of high grade tumors, so 38% of cases showing PNI was attributable to this reason.
7.Presence of adjacent PIN.
Table 6.7: Percentage of cases showing presence of adjacent PIN
in various studies
Study Percentage of cases
Bostwick DG et al85 100
Mc Neal et al86 82
Sakr WA et al87 77
Present study 52%

Histologic transition of high grade PIN to prostate carcinoma has been described.1-3,21 Various studies report high percentages of prostatic carcinomas with PIN. Bostwick DG et al85 found that all cases in his study had adjacent areas of PIN. McNeal et al86 found that 82% of CaPs were assosciated with adjacent PIN areas. Sakr et al87 found 77% of CaPs harbored adjacent PIN. In present study the percentage of CaPs showing adjacent PIN was 52% .
8.Total percentage of cases in each score in different studies on Ki67 expression in prostate carcinoma. Gleason scoring system is the most important prognostic factor in CaP,hence several studies on emerging biomarkers are studied in correlation to Gleason score. Several methods for grouping of Gleason scores in prognostic categories have been proposed. Gleason scores 2 to 4 behave similarly and can be grouped. Gleason scores 8 to 10 are usually grouped together as they represent poorly differentiated tumors. Gleason score 7 is a distinct entity with prognosis intermediate between that of Gleason scores 5-6 and 8 to 10, respectively.21Hence we grouped the patients into four groups wherein Gleason score of 2-4 represent well differentiated tumors, score 5&6 intermediate grade tumors, score 7 moderately differentiated tumors and score 8 and above high grade tumors. The various studies on Ki67 expression use different grouping of Gleason scores. The studies mentioned in the table used same system as followed in present study and the comparative data is presented as
follows.
Table 6.8: Percentage of cases in each score in different studies Gleason score 2-4 5&6 7 8 & above
Madani SH et al69 6.1% 28.5% 22.4% 43%
Mesko S et al88 0 44% 35% 21%
Fisher G et al68 0 29% 45% 26%
Present study 0 21% 40% 39%

A study by Madani et al69 had maximum number of high grade tumors. Another study by Mesko et al88 had maximum number of intermediate grade tumors. Our study patient cohort is similar to study by Fisher G68 with more number of moderately differentiated tumors.
9.Different percentages of ki67 labelling index in different studies.
Table 6.9: Percentages of cases in different ranges of Ki67 LI Study
Ki67 LI Madani et al69 Munoz E et al54 Fisher G68 present study
75% 6.3 14.3 0 3

Various studies report different ranges of Ki67 expression in CaPs in their studies. Different studies have used different grading system for assessing Ki67 labelling index as described in literature. We used grading system given by Madani SH et al.69 In a study by Fisher G et al68 & Madani et al69 the maximum number of cases showed positivity in the range of 2-25%. In our study, results were comparable to Munoz E et al54,with maximum cases(85%) with Ki67 immunolabelling index in the range of 25-75%. Lack of internationally accepted criteria for grading Ki67 accounts for differing data. Variation may also be due to different number of cases with different Gleason score constituting the cases in each study. One more reason for reporting of less percentage of Ki67 labelling index might be its heterogeneity profile.88