Impact of Cribriform Pattern and Intraductal Carcinoma on Gleason 7 Prostate Cancer Treated with External Beam Radiotherapy.

Purpose: We assessed the impact of cribriform pattern and/or intraductal carcinoma on Gleason 7 prostate cancer treated with external beam radiotherapy.

Methods: We evaluated men with Gleason 7 (Grade Groups 2 and 3) prostate cancer treated with dose escalated external beam radiotherapy with or without androgen deprivation. We reviewed biopsies for the presence of cribriform pattern and/or intraductal carcinoma. Study end points included biochemical recurrence-free, distant metastasis-free and disease specific survival.

Results: In the 237 patients median followup was 117 months (range 3 to 236). According to National Comprehensive Cancer Network® risk groups 24% of patients were at favorable intermediate risk, 53% were at unfavorable intermediate risk and 23% were at high risk. The rate of cribriform pattern without intraductal carcinoma, cribriform pattern with intraductal carcinoma, intraductal carcinoma without cribriform pattern and none of these morphologies was 36%, 13%, 0% and 51%, respectively. On multivariable analysis cribriform pattern with intraductal carcinoma (HR 4.22, 95% CI 2.08-8.53, p <0.0001), prostate specific antigen 10 to 20 ng/ml (HR 1.97, 95% CI 1.03-3.79, p=0.04) and prostate specific antigen greater than 20 ng/ml (HR 2.26, 95% CI 1.21-4.23, p=0.01) were associated with worse biochemical recurrence-free survival. On multivariable analysis only cribriform pattern with intraductal carcinoma was associated with inferior distant metastasis-free survival (HR 4.18, 95% CI 1.43-12.28, p=0.01) and disease specific survival (HR 14.26, 95% CI 2.75-74.04, p=0.0016). Factors associated with cribriform pattern with or without intraductal carcinoma included Grade Group 3, high risk group and 50% or more positive biopsy cores. When stratified by neither morphology present, cribriform pattern without intraductal carcinoma and cribriform pattern with intraductal carcinoma the differences in biochemical recurrence-free, distant metastasis-free and disease specific survival were statistically significant (p=0.00042, p=0.017 and p <0.0001, respectively).

Conclusions: Cribriform pattern with intraductal carcinoma was associated with adverse outcomes in men with Gleason 7 prostate cancer treated with external beam radiotherapy while cribriform pattern without intraductal carcinoma was not so associated. Future studies may benefit from dichotomizing these 2 histological entities.