Primary tumor pathology predicts PSMs in prostate surgery patients
MedWire News: Tumor biology and aggressiveness are the most relevant predictors of positive surgical margins (PSMs) after prostate cancer surgery, according to Italian research.
“In most surgical series, PSMs are an independent predictor of biochemical recurrence and local disease recurrence as well as the need for secondary cancer treatment,” explain Vincenzo Ficarra and team from the University of Padua in Italy.
The researchers prospectively analyzed the medical records of 322 patients who underwent robot assisted laparoscopic radical prostatectomy (RALP) to assess pre-operative, surgical, or pathologic predictors of PSMs. Variables included age, Gleason score, clinical T stage, prostate volume on trans rectal ultrasound (TRUS), and pathologic T stage.
Secondary objectives of the study included identifying factors predictive of posterolateral and multiple PSMs, and PSMs in organ-confined tumors. PSMs in the posterolateral region have been previously identified as those that most strongly predict biochemical relapse in patients undergoing RALP.
In all, 29.5% of patients experienced PSMs, with 6.8% in the apex, 1.6% in the anterior, and 21.0% in the posterolateral regions. There were 22 (9%) patients with multiple PSMs.
On univariate analysis, prostate volume on TRUS, Gleason score in the RALP specimen, and the presence of extraprostatic extension were all predictive of any and posterolateral PSMs. Additionally, pathologic T stage, Gleason score in the RALP specimen, and the presence of perineural invasion were significantly associated with multiple PSMs.
On multivariate analysis of pre-operative factors, prostate volume on TRUS of 40 cc or less versus above 40, and clinical T stage (cT1 vs cT2) were independent predictors of PSMs, with hazard ratios of 0.420 and 2.217, respectively.
The most significant independent predictors of posterolateral PSMs were clinical T stage (cT1 vs cT2) and biopsy Gleason score (8–10 vs 6 or less), which increased the risk two-fold and nearly four-fold, respectively.
Pathologic T stage (pT2 vs pT3–4) was the only pathologic variable that significantly predicted PSMs, increasing the risk by 77%.
In patients with organ-confined disease, only the presence of tumor invasion in the perineural region was significantly associated with PSMs on multivariate analysis.
Of 267 patients available for 12-month follow-up, 96.8% were free from biochemical recurrence and not receiving adjuvant therapy. The rates of PSMs at RALP had a significant impact; 98.2% of patients with negative SMs after RALP were free from disease, compared with 93.8% of patients with PSMs.
However, the researchers conclude: “The currently available follow-up duration was not long enough to allow definitive analysis of the prognostic role of PSM number and site in recurrence-free survival probability.”
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By Sarah Guy