[867] Correlation of Conventional and Modified Gleason Grading of Prostatic Adenocarcinoma after Radical Prostatectomy

H Samaratunga, B Delahunt, D Duffy, J Yaxley. Sullivan Nicolaides Pathology, Brisbane, Queensland, Australia; Wellington School of Medicine and Health Sciences, University of Otago - Wellington, Wellington, Otago, New Zealand; Queensland Institute of Medical Research, Brisbane, Queensland, Australia; Royal Brisbane Hospital, Brisbane, Queensland, Australia

Background: The modified Gleason system recommends assigning a score to each separate tumor nodule in radical prostatectomy (RP) specimens with the assumption that outcome will depend on the highest score. This is different to the practice with the conventional method in which a score is given for the entire tumor combined. It is not known how the modified Gleason system compares with conventional system when correlated with pathological parameters in RP specimens.
Design: Three hundred and sixty consecutive RP specimens were graded according to the conventional and the modified Gleason systems.
Results: A total of 29 cases (8%) were upgraded from Gleason score (GS) 7 with a tertiary pattern 5 to GS 9. Twenty of these cases (69%) had extraprostatic extension (pT3a) and 8 (27%) surgical margin (SM) positivity. When both systems were in agreement, cases with GS 7 with tertiary pattern 5 were pT3a in 36 of 63 cases (57%) and SM positive in 17 (26%) cases and GS 9 were pT3a in 15 of 20 (75%) and SM positive in 9 (45%) cases. Seminal vesicle involvement (pT3b) and lymph node positivity were seen in 24% and 3.4% in the upgraded cases, compared with 11% and 0% in the GS 7 with tertiary pattern 5 group and 40% and 15% in the GS 9 cases. The mean tumor volume for the upgraded cases was 4.25 cc compared with 4.0 cc for the GS 7 with tertiary pattern 5 and 5.5 cc for the GS 9 cases. Cases upgraded to GS 9 in the modified system were more likely to present with high stage disease than GS 7 with tertiary pattern 5, but not as likely as GS 9 in the conventional system (Exact P value = 0.133 Trend P-value 0.04 17). Of 26 cases of GS 3+4 with tertiary pattern 5, 10 cases were upgraded to GS 4 + 3 with tertiary pattern 5. This significantly improved prediction of extraprostatic extension (Exact P = 0.04).
Conclusions: The modified Gleason system appears to improve prediction of pathological stage, when compared with the conventional Gleason system.
Category: Genitourinary (including renal tumors)

Tuesday, March 10, 2009 9:30 AM

Poster Session III # 87, Tuesday Morning