Prognosis of Gleason score 8 prostatic adenocarcinoma in needle biopsies: a nationwide population-based study

A 5-tier grouping of Gleason scores has recently been proposed. Studies have indicated prognostic heterogeneity within these groups. We assessed prostate cancer-specific mortality (PCSM) and all-cause mortality (ACM) for men diagnosed with Gleason score 3 + 5 = 8, 4 + 4 = 8 and 5 + 3 = 8 acinar adenocarcinoma on needle biopsy in a population-based national cohort. The Prostate Cancer data Base Sweden 5.0 was used for survival analysis with PCSM and ACM at 5 and 10 years as endpoints. Multivariable Cox regression models controlling for socioeconomic factors, stage and primary treatment type were used for PCSM and ACM. Among 199,620 men reported with prostate cancer in 2000-2020, 172,112 were diagnosed on needle biopsy. In 18,281 (11%), there was a Gleason score of 8 in needle biopsies, including a Gleason score of 3 + 5, 4 + 4 and 5 + 3 in 11%, 86% and 2.3%, respectively. The primary treatment was androgen deprivation therapy (55%), deferred treatment (8%), radical prostatectomy (16%) or radical radiotherapy (21%). PCSM in men with Gleason scores of 3 + 5, 4 + 4 and 5 + 3 at 5 years of follow-up was 0.10 (95% CI 0.09-0.12), 0.22 (0.22-0.23) and 0.32 (0.27-0.36), respectively, and at 10 years 0.19 (0.17-0.22), 0.34 (0.33-0.35) and 0.44 (0.39-0.49), respectively. There was a significantly higher PCSM after 5 and 10 years in men with Gleason score 5 + 3 cancers than in those with 4 + 4 and in Gleason score 4 + 4 cancers than in those with 3 + 5. Grouping of Gleason scores will eliminate the prognostic granularity of Gleason scoring, thus diminishing the prognostic significance of this proposed grading system.