Residual benign prostate glandular tissue not tied to detectable PSA after radical prostatectomy: Study

Radical prostatectomy (RP) is the established treatment modality for clinically localized prostate cancer. Ideally, serum prostate specific antigen (PSA) values should become undetectable after RP; however, studies have found detectable PSA in up to 16.4% of men after definitive treatment, without oncologic recurrence. After RP, 28%–73% will have benign glandular tissue at the surgical margin (BGM) diagnosed on surgical pathology. There is a concern that benign, rather than malignant, residual tissue could account for detectable serum PSA after RP, especially low serum PSA values.

In many previous studies, benign glandular tissue at the surgical margin (BGM) has been evaluated as a potential risk factor for biochemical recurrence (BCR) and poor disease prognosis in open radical prostatectomies (ORPs), but no difference in patient outcomes were seen based on benign glandular tissue at the surgical margin (BGM)-status. However, with the current widespread use of robotic assisted laparoscopic radical prostatectomy (RALP) there is a paucity of data evaluating the association of BGM and postoperative detectable PSA or risk of BCR despite comparative studies indicating an increased risk of BGM with RALP compared to ORP.

Study design

The study was reported by researchers at The University of California, San Francisco's (UCSF) on clinical urologic outcomes database to identify patients treated with either ORP or RALP between 2004–2018. They studied "if benign glandular tissue at the surgical margin (BGM) is associated with detectable prostate specific antigen (PSA) and/or biochemical recurrence (BCR) after radical prostatectomy (RP)."

In this study surgical specimens were received by pathologists intact and inked for margin analysis. The gross specimen was subsequently serially cross-sectioned at 3–6 mm intervals perpendicular to the urethral axis. BGM was defined as benign prostatic glands at the inked margin and reported as a binary variable (present/absent). Malignancy at the surgical margin (MSM) was defined as tumor at the inked margin.

The researchers used regression analysis to identify demographic, clinical and surgical factors associated with the likelihood of BGM presence on surgical pathology. Oncologic outcomes included detectable PSA (>0.03 ng/ml), BCR (≥0.2 ng/ml) and progression to BCR or salvage treatment after detectable PSA

Results:

• "In 1,082 men followed for a median time of 49 months, the presence of BGM after RP is not associated with an increased risk of MSM, detectable PSA, BCR, or progression from detectable PSA to BCR or salvage treatment."

• BGM was present on 249 (23%) specimens. Younger age, bilateral nerve sparing surgery and robotic approach were associated with presence of BGM while malignancy at the surgical margin (MSM) was not.

• In the subgroup of men who reached detectable PSA, 79% had progression within 7 years.

• At 7 years after RP, 29% experienced detectable PSA and 11% had BCR.

• To date, this is the largest study evaluating BGM outcomes after RALP and the first to evaluate the association between BGM and risk of detectable PSA.

• Although RALP for the surgical treatment of prostate cancer has been widely adopted, contemporary data regarding the association of BGM and BCR has been lacking despite multiple studies demonstrating an increased risk of BGM with RALP.

• As there was no difference in detectable PSA or BCR between BGM-present and BGM-absent cohorts, the theoretically more aggressive approach to preserve functional outcomes appears to be of no consequence in this study.

Conclusion

The researchers concluded that "The presence of benign glandular prostatic tissue at RP was not associated increased risk of Malignancy at the surgical margin (MSM), detectable PSA, BCR, progression from detectable PSA to BCR or salvage therapy."

Source: Greenberg SA et al.; J Urol. 2021 Sep 1;206(3):706–14. https://doi.org/10.1097/JU.0000000000001793