Active Monitoring, Surgery, and Radiotherapy for Cribriform-Positive and Cribriform-Negative Prostate Cancer: A Secondary Analysis of the PROTECT Randomized Clinical Trial.

Importance: Cribriform prostate cancer is associated with poor outcomes; however, its optimal treatment strategy remains unclear in the absence of randomized data. Objective: To retrospectively analyze the results of the PROTECT randomized clinical trial to establish the association between cribriform-positive and cribriform-negative prostate cancer and 15-year risk of metastasis in patients who underwent active monitoring, surgery, or radiotherapy. Design, Setting, and Participants: Between 1999 and 2009, the PROTECT phase 3 randomized clinical trial enrolled 1643 men with clinically localized prostate cancer who were randomly assigned to receive active monitoring, surgery, or radiotherapy with neoadjuvant androgen deprivation therapy (ADT). In this secondary analysis of the PROTECT trial, a centralized histopathologic review was conducted on available diagnostic biopsy slides to classify patients as cribriform-positive if they had invasive cribriform carcinoma and/or intraductal carcinoma. Data were collected from January 25, 2024, to October 11, 2024, and were analyzed from October 14, 2024, to January 30, 2025. Exposures: Age, prostate-specific antigen (PSA), Gleason score, and cribriform status. Main Outcomes and Measures: The primary outcome was progression to metastatic disease (bony, visceral, or lymph node metastases on imaging or PSA >100 ng/mL). Multivariable Cox proportional hazards regression models, adjusted for randomization variables, were incorporated to assess 15-year metastasis risk. Cumulative incidence curves were compared using the Gray test. Both intention-to-treat and per-protocol analyses were performed. Results: Among 712 men (mean [SD] age, 62.0 [5.0] years) whose biopsies were retrospectively reviewed, 93 (13.1%) had cribriform-positive disease and 42 (5.9%) developed metastasis. In the intention-to-treat cohort, cribriform-positive disease significantly increased the risk of metastasis (hazard ratio [HR], 3.61 [95% CI, 1.60-8.11]; P = .003). Radiotherapy with neoadjuvant ADT significantly reduced metastasis risk (HR, 0.35 [95% CI, 0.16-0.78]; P = .04) (15-year cumulative incidence in patients with cribriform-positive disease, 8%), while surgery delayed metastasis but did not significantly improve long-term outcomes compared with active monitoring (HR, 0.52 [95% CI, 0.25-1.08]; P = .09) (15-year cumulative incidence in patients with cribriform-positive disease, 26% for surgery and 25% for active monitoring). Among patients with cribriform-negative disease, incidence of metastasis was low and did not differ by treatment. Similar per-protocol results were noted. Conclusions and Relevance: The findings of this secondary analysis of the PROTECT randomized clinical trial suggest that cribriform morphology was a strong, independent predictor of 15-year metastasis among patients with prostate cancer and that radiotherapy with neoadjuvant ADT was associated with a reduced long-term risk of metastasis. Conversely, outcomes were favorable for most patients with cribriform-negative disease, supporting their eligibility for active surveillance. Trial Registration: ClinicalTrials.gov Identifier: NCT02044172.