Results

The study cohort comprised 73 prostate adenocarcinoma biopsy cases with available Decipher genomic testing. Based on Decipher results, cases were stratified into three risk categories: low risk (LR; n=28), intermediate risk (IR; n=18), and high risk (HR; n=27).

Although mean age and diagnostic PSA levels showed a gradual increase across the LR, IR, and HR groups, these trends did not reach overall statistical significance (Table 1). However, pairwise analysis demonstrated that the mean age was significantly higher in the HR group compared with the LR group (t=2.17, p=0.03). Given the non-significant omnibus result, this finding should be interpreted as exploratory rather than confirmatory. No significant differences in PSA levels were observed between any risk groups.

Variable | Low risk (n=28) | Intermediate risk (n=18) | High risk (n=27) | p-value (test statistic)
Age, mean±SD (years) | 63.9±9.4 | 67.0±7.7 | 68.5±6.4 | 0.06 (F=2.35)
PSA, mean±SD (ng/mL) | 9.4±5.7 | 10.1±6.4 | 10.4±6.4 | 0.6 (H=0.86)
Metastasis at the time of the study, number (%) | 0 (0%) | 0 (0%) | 1 (3.7%) | NS
Vital status, number (%) | 28 alive (100%) | 18 alive (100%) | 27 alive (100%) | NS

Grade group (GG) distribution differed significantly across the Decipher risk groups (χ²=16.6, p = 0.03). In the LR group, there were 6 GG1, 20 GG2, 1 GG3, and 1 GG5 cases; in the IR group, there were 1 GG1, 13 GG2, 3 GG3, and 1 GG4 cases; and in the HR group, there were 1 GG1, 13 GG2, 9 GG3, 3 GG4, and 1 GG5 cases. The majority of cases across all groups were GG2. Pairwise comparisons demonstrated a significant difference between the HR and LR groups (χ²=12.8, p=0.006), primarily driven by a higher proportion of GG3 tumors in the HR group and a higher proportion of GG1 tumors in the LR group. A near-significant difference was noted between the IR and LR groups (p=0.05), primarily driven by the higher prevalence of GG3 in the IR group. No significant difference was observed between the HR and IR groups (Table 2 and Table 3).

Variable | Low risk (n=28) | Intermediate risk (n=18) | High risk (n=27) | p-value (test statistic)
Grade group 1, number (%) | 6 (21.4%) | 1 (5.6%) | 1 (3.7%) | 0.03 (Fisher’s exact, Freeman-Halton)
Grade group 2, number (%) | 20 (71.4%) | 13 (72.2%) | 13 (48.1%)
Grade group 3, number (%) | 1 (3.6%) | 3 (16.7%) | 9 (33.3%)
Grade group 4, number (%) | 0 (0%) | 1 (5.6%) | 3 (11.1%)
Grade group 5, number (%) | 1 (3.6%) | 0 (0%) | 1 (3.7%)
Positive core ratio, mean±SD | 0.44±0.19 | 0.54±0.29 | 0.64±0.26 | 0.01 (F=4.29)
Maximum tumor length ratio, mean ± SD | 0.47±0.28 | 0.51±0.3 | 0.67±0.27 | 0.01 (F=4.72)
Extraprostatic extension, number (%) | 0 (0%) | 0 (0%) | 3 (11.1%) | 0.07 (Fisher’s exact)
Intraductal carcinoma, number (%) | 0 (0%) | 0 (0%) | 3 (11.1%) | 0.07 (Fisher’s exact)
Cribriform pattern, number (%) | 7 (25.0%) | 7 (38.9%) | 12 (44.4%) | 0.3 (χ²=2.37)
Perineural invasion, number (%) | 4 (14.3%) | 5 (27.8%) | 7 (25.9%) | 0.4 (χ²=1.56)
Necrosis, number (%) | 0 (0%) | 0 (0%) | 0 (0%) | NS
Neuroendocrine differentiation, number (%) | 0 (0%) | 0 (0%) | 0 (0%) | NS

Variable | LR versus IR | LR versus HR | IR versus HR | Overall p-value (test statistic)
Age (years) | p=0.28 (t=1.08) | p=0.03 (t=2.17) | p=0.59 (t=0.54) | p=0.06 (F=2.35)
PSA (ng/mL)† | Adj. p=1.000 (Z=-0.359) | Adj. p=0.052 (Z=-2.460) | Adj. p=0.204 (Z=-1.825) | p=0.6 (H=0.86)
Grade group distribution | p=0.05 (Fisher’s exact) | p=0.006 (Fisher’s exact) | p=0.14 (Fisher’s exact) | p=0.03 (Fisher’s exact)
Positive core ratio | p=0.21 (t=1.27) | p=0.003 (t=3.10) | p=0.18 (t=1.36) | p=0.01 (F=4.29)
Maximum tumor length ratio | p=0.71 (t=0.37) | p=0.01 (t=2.64) | p=0.09 (t=1.73) | p=0.01 (F=4.72)

The Decipher risk groups also demonstrated significant differences in mean positive core ratio and maximum tumor length ratio (both F≈4.2-4.8, p=0.01). The mean positive core ratios were 0.44, 0.54, and 0.64 for the LR, IR, and HR groups, respectively, with the HR group showing a significantly higher proportion of positive cores compared with the LR group (t=3.10, p=0.003). Similarly, the mean maximum tumor length ratios were 0.47, 0.51, and 0.67 for the LR, IR, and HR groups, respectively. The HR group demonstrated significantly greater tumor length compared with the LR group (t=2.64, p=0.01) (Table 2 and Table 3).

Aggressive histopathologic features, including the presence of cribriform pattern, extraprostatic extension, perineural invasion, intraductal component, necrosis, and neuroendocrine differentiation, showed no statistically significant differences across the Decipher risk groups.

Figure 1 presents histopathologic features observed in high-risk Decipher group cases.

Figure 1: Representative histopathologic features observed in high-risk Decipher group cases(A) Cribriform pattern. (B) Intraductal carcinoma. (C) Extraprostatic extension.

Regarding clinical outcomes, only a single instance of metastasis was documented, which occurred within the high-risk (HR) group. No cancer-related mortality or other patient deaths were recorded during the study period.