Assessment of low prostate weight as a determinant of a higher positive margin rate after laparoscopic radical prostatectomy: a prospective pathologic study of 1,500 cases.

Background: The assessment of prostate weight as a determinant of a high prostate margin rate after laparoscopic radical prostatectomy has not been studied.

Methods: Prospective pathologic findings of 1,500 patients who underwent laparoscopic radical prostatectomy (LRP, 399 cases) and da Vinci prostatectomy (DVP, 1,101 cases) between December 2000 to June 2006 at City of Hope National Medical Center were evaluated. Gleason score, pathologic stage, the presence or absence of positive margins, extraprostatic tumor extension, and seminal vesicle involvement by tumor were recorded in all patients. Preoperational serum prostate specific antigen (PSA) levels were recorded in all but 13 cases. These parameters were then correlated with prostate weight.

Results: Of 1,500 patients, 345 had one or more positive margins (23%). Patients with low median prostate weight (49 g) had a significantly higher positive margin rate (p < 0.0001) and incidence of extraprostatic extension by tumor (p = 0.04), and were 1.523 times more likely to have positive margins [95% confidence interval (CI) 1.167-1.985].

Conclusion: We conclude that low prostate weight may be a determinant of a higher recurrence rate and more aggressive disease.