Prognostic significance of histologic grading in patients with prostate carcinoma who are assessed by the Gleason and World Health Organization grading systems in needle biopsies obtained prior to radiotherapy

BACKGROUND. The current study was conducted to evaluate and compare the imp act of two major histologic grading systems on failure-free survival in pat ients with prostate carcinoma who are treated with definitive radiation. METHODS. Eligible patients for the current study had localized adenocarcino ma of the prostate (T1-4pN0M0, T3/4: 67%, median observation time: 69 month s) and were treated with intent-to-cure external radiotherapy between 1989 and 1995. The specimens from 178 patients, obtained by needle biopsies, wer e reviewed simultaneously by two pathologists assigning World Health Organi zation (WHO) and Gleason grades. Three-tiered Gleason grouping distributed patients into three groups (those with a score ( 7, those with a score of 7 , and those with a score of 8-10), whereas two-tiered Gleason categorizatio n distributed patients into two groups (those with a Gleason score of 7A, m ajor 3 + minor 4 patients were added to the group of patients with a Gleaso n score < 7 and patients with a Gleason score of 7B, major 4 + minor 3 were added to the group of patients with a Gleason score of 8-10). Univariate a nd multivariate analyses were performed. A P value < 0.05 was considered to be statistically significant. RESULTS. Three-tiered Gleason grouping resulted in a relatively even distri bution of the patients (44 patients had a Gleason score < 7, 58 patients ha d a Gleason score of 7, and 76 patients had a Gleason score of 8-10) wherea s 130 patients were determined to have Grade 2 tumors based on WHO criteria . Separating those patients with a Gleason score of 7 (score 3+4 vs. score 4+3) led to the two-tiered Gleason grouping (88 patients in the favorable g roup and 90 patients in the unfavorable group). The two-tiered Gleason grou ping displayed differences with regard to failure-free survival with the lo west P values for all patients and separately for T1/2 versus T3/4 tumors. Together with T category and pretreatment prostate specific antigen, WHO gr ading, three-tiered Gleason grouping, and two-tiered Gleason grouping resul ted in independent parameters in the Cox regression model. The proportional variance estimate confirmed the superior discrimination for survival of tw o-tiered Gleason grouping. CONCLUSIONS. The equal allocation of patients to subgroups based on the Gle ason system helps the clinician to overcome the dilemma of overrepresentati on of Grade 2 patients as occurs with WHO grading. The Gleason grading syst em and, most likely, the two-tiered Gleason grouping appear to result in be tter prognostic separation of patients referred to radiotherapy for relativ ely advanced primary tumors. Therefore the authors recommend the routine us e of Gleason grading for these patients. (C) 2001 American Cancer Society.