# Assessment of Local and Metastatic Recurrence Following Robot-Assisted Radical Prostatectomy by Margin Status Using PSMA PET/CT Scan

## TL;DR

This study shows that having cancer-free surgical margins after prostate removal does not significantly reduce the risk of cancer returning locally or spreading, based on PSMA PET scans.

## Contribution

The study challenges the assumption that negative surgical margins improve cancer outcomes using PSMA PET/CT scans in men with rising PSA after surgery.

## Key findings

- Local recurrence rates were similar between men with negative and positive surgical margins.
- Lymph node and bone metastasis rates were also comparable regardless of margin status.
- Margin status was not a significant predictor of local recurrence in multivariate analysis.

## Abstract

After radical prostatectomy (RP), many clinicians assume that having “negative surgical margins,” (meaning all cancer was fully removed) lowers the chance of cancer returning locally. However, our study of 159 men who developed a rise in PSA after RP challenges this long-held belief. Using PSMA PET/CT scans, which is one of the most sensitive imaging tools for detecting recurrent prostate cancer, we found that men with positive and negative surgical margins had nearly identical rates of local recurrence, as well as similar rates of lymph node and bone metastases. Our results illustrate that pursuing wider resections to achieve negative margins, often at the cost of urinary continence and erectile function, may not improve outcomes. Earlier detection and timely evaluation with PSMA PET may be more important for long-term cancer control than margin status alone.

Background: Local recurrences following radical prostatectomy (RP) are typically attributed to incomplete surgical resection or positive surgical margins (PSMs). Yet approximately 70% of men with PSMs never experience BCR. Prostate-specific membrane antigen PET scans (PSMA PET) are useful in detecting the incidence and location of recurrence sites. This study explores the relationship between margin status and local and metastatic recurrences using PSMA PET scans. Methods: A retrospective study was conducted with prospectively collected data following RARP with BCR in 159 men undergoing PSMA PET (2017–2023). The primary outcome compared risk and location of recurrences between NSM vs. PSM. A total of 13 cases (8%) had “equivocal” PET scan findings which were assessed first as all positive and then all negative. Results: Of 159 men with BCR undergoing PSMA PET scans, 101 (63.5%) had NSMs and 58 (36.5%) had PSMs. Assuming all 13 “equivocal” scans were positive, the risk of a positive PSMA PET is NSMs vs. PSMs (73% vs. 69% p = 0.56). Local recurrence rates did not differ significantly (NSMs 39.2% vs. PSMs 45% p = 0.55), nor did lymph nodes (NSMs 61% vs. PSMs 58% p = 0.73) or bone lesions (NSMs 16.2% vs. PSMs 22.5% p = 0.41). Multivariate regression analysis showed that margin status was not a predictor of local recurrence (OR 1.40; 95% CI [0.65, 1.54]; p = 0.382). Conclusions: Local recurrence occurs at about the same rate independent of margin positivity status, suggesting that local recurrences appear to be more closely related to metastatic dissemination, not incomplete resection. These findings question the oncologic rationale for wider resections at the expense of functional outcomes.