Aims: The aim is to assess for a difference in the incidence of metastasis (IM) and prostate-specific antigen (PSA) levels at diagnosis in patients with Gleason score (GS) 3+4 versus 4+3 prostate cancer using a large veterans affairs database.
Subjects and methods: A retrospective review of 1402 medical records from 5 VA hospitals was conducted. The study period was from 2009 to 2014. Primary endpoints were IM and PSA levels at diagnosis. A secondary endpoint was overall survival.
Statistical analysis used: Chi-square tests for categorical variables, Student's t-test for continuous, normally distributed variables, and rank sum tests for continuous nonnormally distributed variables.
Results: There were 1050 patients with GS3+4 and 352 with GS4+3. There were no differences in sociodemographic and clinical characteristics of the study population. PSA at the time of diagnosis was significantly higher in the GS4+3 patients compared to GS3+4 (18.0 vs. 11.4, respectively; P < 0.001). The IM at diagnosis was higher in the GS4+3 patients (10/352) compared to GS3+4 (9/1041) (2.8% vs. 0.9%; P = 0.005). In an adjusted model, GS4+3 was associated with higher PSA, higher IM at diagnosis. There was no difference in overall survival between the 2 groups though a 23% reduction in overall survival in the GS4+3 was noted (P = 0.53).
Conclusions: Our results indicate that patients with GS4+3 prostate cancers have higher PSA levels at diagnosis. GS4+3 is associated with 3-fold increased risk of IM at diagnosis than GS3+4 though the overall incidence is low. Further research is needed to assess whether GS4+3 patients need routine staging imaging investigations at the time of diagnosis similar to patients with higher Gleason scores (GS ≥8).
Keywords: Cancer; Gleason score; metastasis; prostate; prostate-specific antigen.