Risk factors for seminal vesicle invasion at radical prostatectomy.

purposeTo comprehensively assess predictors of seminal vesicle invasion (SVI) at radical prostatectomy given the low sensitivity of magnetic resonance imaging (MRI).

methodsBetween 2017 and 2025, 4,448 patients underwent radical prostatectomy alone. Multivariable logistic regression was used to identify clinicopathological and MRI-related predictors of pathologic SVI, including age, Black race, PSA, PSA density, clinical T stage, Grade Group, percentage of positive cores, basal tumor involvement on systematic biopsy, the location of PI-RADS 4/5 lesions (apex/midgland/base), and MRI-suspected extracapsular extension and SVI. The same variables were evaluated in patients without MRI-detected SVI (n = 4,358). Model discrimination was assessed using the AUC.

resultsPathologic SVI prevalence was 6.9% (305/4,448). MRI demonstrated 17% sensitivity and 99% specificity. Independent clinicopathological predictors (all p < 0.04) were Black race (OR 1.48), log-PSA (OR 2.30/1-unit), Grade Groups 3–5 (OR 2.56–4.32), percentage of positive cores (OR 1.21/10%), and basal tumor involvement on biopsy (OR 1.92). MRI-related independent predictors (all p < 0.01) were SVI (OR 15.7), extracapsular extension (OR 1.69), and midgland (OR 1.49) and basal (OR 1.92) PI-RADS 4/5 lesions; apex lesions were inversely associated (OR 0.64). These associations remained significant in the MRI-negative subgroup. The model showed good discrimination (AUC 0.80, 95% CI 0.77–0.82), remaining robust in MRI-negative patients (AUC 0.76, 95% CI 0.73–0.79). Limitation included selection bias toward favorable-risk features by excluding patients with hormonal therapy.

conclusionMultifactorial risk assessment, particularly including tumor location, helps mitigate MRI’s limited sensitivity for SVI detection and could inform surgical or radiation planning in patients at risk of SVI.