The pathway of isolated seminal vesicle invasion has a different impact on biochemical recurrence after radical prostatectomy and pelvic lymphadenectomy

Objective: Prostate cancer with seminal vesicle invasion (SVI) has been considered an aggressive cancer. To evaluate the prognostic significance of different patterns of isolated SVI in patients undergoing radical prostatectomy (RP) and pelvic lymphadenectomy. Methods and materials: We retrospectively analyzed all patients who underwent RP between 2007 and 2019. Inclusion criteria were localized prostate adenocarcinoma, SVI at RP, at least 24-months follow-up, and no adjuvant treatment. Patterns of SVI were following Ohori's classification: type 1: direct spread along the ejaculatory duct from inside; type 2: seminal vesicle invasion outside the prostate, through the capsule; type 3: the presence of cancer island(s) in the seminal vesicle with no continuity from the primary tumor (discontinuous metastases). Patients with type 3 SVI (isolated or in association) were included in the same group. Biochemical recurrence (BCR) was defined as any postoperative PSA ≥0.2 ng/ml. A logistic regression analysis was performed to assess predictors of BCR. Time to BCR was investigated using the Kaplan-Meier analysis with the log-rank test. Results: Sixty-one out of 1,356 patients were included. Median age was 67(7.2) years. Median PSA was 9.4(8.92) ng/ml. Mean follow-up was 85.28 ± 45.27 months. BCR occurred in 28(45.9%) patients. Logistic regression showed that a positive surgical margin (OR 19.964, 95%CI:1.172-29.322, P = 0.038) was predictor of BCR. Kaplan-Meier analysis demonstrated that patients with pattern 3 had a significantly shorter time to BCR compared to other groups (log-rank, P = 0.016). The estimated time to BCR was 48.7 months in type 3, 60.9 months in pattern 1 + 2, 74.8, and 100.8 months in isolated patterns 1 and 2, respectively. In patients with negative surgical margins, pattern 3 confirmed a shorter time to BCR compared to other types of invasions, with an estimated time to BCR of 30.8 months. Conclusions: Patients with type 3 SVI demonstrated a shorter time to BCR compared to other patterns.