Prognostic Implications of Modified Gleason Score and Gleason Grade Group in Histopathologic Study of Prostatic Adenocarcinoma: A Cross-sectional Study

Introduction: The Gleason Score (GS) is the most powerful prognostic indicator in prostatic carcinoma. The assignment of the GS is based on the histopathologic patterns of prostatic adenocarcinoma, which are classified according to the Gleason Pattern (GP). Periodic revisions in the definitions of the GP Score are attempted by the International Society of Urologic Pathology (ISUP), followed by the introduction of the Gleason Grade Group (GG) System, which aims to improve prognostication in prostate cancer. Aim: To determine whether the ISUP 2014 GG group system is a better prognostic indicator compared to the ISUP 2005 Modified GS. Materials and Methods: This cross-sectional study was conducted over four years, from January 2016 to December 2019, at the Department of Pathology, SDM College of Medical Sciences and Hospital, Shri Dharmasthala Manjunatheshawara University, Sattur, Dharwad, Karnataka, India. Core biopsies and transurethral resection biopsies of the prostate with a diagnosis of prostatic carcinoma were included in the study. Demographic details, Prostate-specific Antigen (PSA) levels and follow-up data were retrieved from the case files. Histopathology slides from all patients were examined and assigned GS scores from 6 to 10 and GG scores from 1 to 5. The slides were also analysed for the presence or absence of Perineural Invasion (PNI) and Cribriform Pattern (CFP). The percentage of tumour involvement was documented. Patients were followed-up for a period of two to five years for evidence of metastasis and/or death due to prostatic carcinoma. Categorical variables were analysed using descriptive statistics. Results: The mean age of presentation was 70.21 years. A total of 52 cases were included in the study, with a histopathological diagnosis of adenocarcinoma in all cases. Three special variants were encountered, including one case each of Signet Ring Cell Carcinoma (SRCC), pseudo hyperplastic adenocarcinoma and intraductal foamy gland carcinoma. The distribution of GG scores was as follows: 7 (13.46%) for GG 1, 5 (9%) for GG 2, 6 (11.5%) for GG 3, 8 (15.38%) for GG 4 and 26 (50%) for GG 5. There were 23 cases with metastasis, with most belonging to GG 5 and GG 4. PNI and CFP were noted in 34 (65.38%) and 25 (48.07%) cases, respectively. Tissue cores with greater than 50% tumour involvement were observed in 32 cases (61.53%). Conclusion: The current study underscores the prognostic importance of the ISUP 2014 GG system over the ISUP 2005 GS system. Histomorphological parameters such as PNI, CFP and a percentage of tumour involvement greater than 50% significantly influence prostate cancer prognosis. These factors may provide valuable information for optimal clinical management.