Quantitative assessment of cribriform intraductal carcinoma of the prostate is useful for risk stratification after radical prostatectomy.

It remains uncertain if the extent of intraductal carcinoma of the prostate (IDC) exhibiting cribriform (Crib) morphology impacts on patient outcomes. We retrospectively analyzed long-term oncologic outcomes in 182 consecutive radical prostatectomy patients exhibiting Grade Group 2-4 conventional/acinar prostatic adenocarcinoma, along with Crib-IDC but no Gleason grade 5 patterns. A single Crib-IDC focus in the entire prostatectomy specimen was identified in 46 (25.3 %) cases, while others showed 2 (n = 36; 19.8 %), 3 (n = 27; 14.8 %), 4 (n = 11; 6.0 %), or ≥5 (n = 62; 34.1 %) Crib-IDC foci. The maximum Crib-IDC diameter in each case was ≤1-mm (n = 66; 36.3 %), >1/≤2-mm (n = 90; 49.5 %), >2/≤3-mm (n = 21; 11.5 %), or >3-mm (n = 5; 2.7 %). The summed maximum Crib-IDC diameters were ≤1-mm (n = 38; 20.9 %), >1/≤2-mm (n = 39; 21.4 %), >2/≤3-mm (n = 30; 16.5 %), >3/≤4-mm (n = 17; 9.3 %), >4/≤5-mm (n = 9; 4.9 %), or >5-mm (n = 49; 26.9 %). On univariate analyses, the risks of postoperative biochemical recurrence were significantly higher in cases with 3 (P = 0.022) or ≥3 (P < 0.001) Crib-IDCs (vs. 1-2) or ≥4 Crib-IDCs [P < 0.001 (vs. 1-3); P = 0.032 (vs. 3)]. Similarly, the recurrence risk was significantly higher in Crib-IDC cases with the maximum diameter of >1-mm (vs. ≤1-mm; P = 0.002) or the summed diameter of >3-mm (vs. ≤3-mm; P < 0.001). On multivariable Cox regression analyses, 3 [hazard ratio (HR) 2.742, P = 0.016], ≥3 (HR 3.969, P < 0.001), or ≥4 (HR 4.520, P < 0.001) Crib-IDCs (vs. 1-2) and the summed diameter of >3-mm (HR 3.074, P < 0.001) remained significantly predictive of recurrence. Quantitative assessment of Crib-IDC, particularly its number and cumulative diameter on prostatectomy, may thus enhance the postoperative risk stratification of Grade Group 2-4 prostate cancer.