Low prostate weight linked to PSMs in low-risk prostatectomy patients
MedWire News: Men with low-risk prostate cancer are more likely to have positive surgical margins (PSMs) after treatment with nerve-sparing robotic-assisted radical prostatectomy (RARP) if they have a light rather than heavy prostate, researchers report.
PSMs are also associated with significantly increased prostate-specific antigen (PSA) levels, high Gleason scores, and high pathological stage disease, show the study results.
"The presence of a PSM is an important factor when analyzing outcomes after radical prostatectomy because they can predict biochemical recurrence and the need for secondary therapy," say Pablo Marchetti and colleagues from the University of Chicago Medical Center in Illinois, USA.
In an era of prostate-specific antigen (PSA)-based screening, significant numbers of men are being diagnosed with well-differentiated cancers of low clinical stage, note Marchetti and team. These men are candidates for bilateral nerve-preserving surgery, they add, and the impact of prostate weight on PSMs in this subgroup is not clear.
Therefore, they analyzed the impact of prostate weight on the probability of PSAs in a cohort of 690 low-risk (clinical stage T1c, PSA <10 ng/ml, biopsy Gleason score ≤6) RARP patients.
After a median follow-up of 19 months, 105 men had a PSM (15.2%), of whom 16.0% experienced biochemical recurrence compared with 3.0% of men with negative margins.
Patients with PSMs had significantly higher PSA levels (5.3 vs 4.8 ng/ml), smaller prostates (45.0 vs 51.2 g), higher Gleason scores (47% vs 29% Gleason score ≥7), and higher pathological stage disease (29% vs 4% T3) than patients with negative margins.
Univariate analysis revealed a significant inverse relationship between prostate weight and incidence of PSM (odds ratio [OR]=0.97), which remained significant after adjustment for factors including age, body mass index, surgeon experience, and Gleason score, at an OR of 0.98.
After stratifying the results of the multivariate analysis by weight, the predicted probability of PSMs for prostates of 25, 50, 100, and 150 g was 22%, 13%, 5%, and 1%, respectively, report the researchers in the journal Urology.
In view of the increased number of RARP patients with small prostates and low-risk tumors, "a lower prostate size must be considered as an independent predictor of PSM and care must be taken during surgery to avoid this complication," conclude Marchetti et al.
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By Sarah Guy