Clinical outcomes of patients with grade group 1 prostate cancer with extraprostatic extension: Results from up to 25 years of follow-up.

387 Background: Grade Group 1(GG1) prostate cancer is typically an indolent disease; however, there are reports of non-organ confined disease on radical prostatectomy (RP). We sought to examine the long-term oncologic outcomes of patients with GG1 prostate cancer who had extraprostatic extension (EPE), bladder neck invasion (BNI), and/or seminal vesical invasion (SVI) confirmed on RP histopathology. Methods: This was a retrospective cohort study examining all patients at our large quaternary institution. Patients with GG1 and pT3 disease on final radical prostatectomy specimen were identified, and pathology slides were re-reviewed by a dedicated genitourinary pathologist to confirm diagnosis. Those without follow-up were excluded. Outcome variables of interest included post-operative PSA, biochemical recurrence (BCR), metastatic disease, and overall survival. Results: We identified 50 patients at our institution that had confirmed GG1 and EPE on RP final pathology between 2000-2022. Our primary cohort consisted of 40 men as 10 had no follow-up data available. Patient characteristics are summarized in Table 1. Median follow-up was 15 years (interquartile range, 5-18 years). 4 patients (10%) experienced BCR, occurring after an average of 8.6 years (range 3-19 years); of the patients that developed BCR within 10 years (N=3), all had positive surgical margins, while the 1 patient that developed delayed BCR had negative margins. 6 men developed a detectable PSA value after an average of 7.6 years but did not cross the threshold for BCR (i.e. 0.2 ng/mL). No patient developed metastatic disease or death from prostate cancer. There were 8 deaths reported in the cohort from other causes. Conclusions: Our study shows that long-term clinical outcomes for patients with GG1 are favorable despite having pT3 disease. With a median follow-up of 15 years, we did not observe any cases of metastatic disease or prostate cancer specific death. While BCR was reported, it occurred in a delayed pattern. Baseline characteristics. Variable Value (N=40) Age, median (IQR) 58 (52 – 64) Pre-operative PSA, mean (SD) 4.5 (3.3) Final Pathology, number (%) T3a EPE 33 (83%) T3a BNI 6 (15%) T3a EPE and BNI 1 (2%) Nodal pathology, number (%) NX 31 (78%) N0 9 (22%) Surgical margin status, number (%) Negative 21 (53%) Positive 19 (47%) Surgical approach, number (%) Open 20 (50%) Laparoscopic 5 (13%) Robot-assisted 15 (32%) EPE, number (%) Focal 23 (58%) Established 17 (42%)