The impact of the extent and location of positive surgical margins on the risk of biochemical recurrence following radical prostatectomy in men with Gleason 7 prostate cancers.

ABSTRACT

BACKGROUND: Positive surgical margins (PSM) after radical prostatectomy (RP) have been associated with increased risk of biochemical recurrence (BCR). This is heavily influenced by other clinicopathological factors. This study aims to assess the impact of the extent and location of PSM on BCR following RP for Gleason 7 carcinoma of the prostate (CaP). MATERIALS AND METHODS: All men treated with RP between 2008 and 2017 in our region for localized or locally advanced Gleason 7 CaP, were included. Clinical (age, year, preoperative prostate specific antigen) and pathological (prostate weight, positive or negative surgical margins, International Society of Urological Pathology [ISUP] grade, T stage) data were collected. PSM were subcategorised according to Extent into favourable (unifocal and <3 mm in length) or unfavourable (multifocal or ≥3 mm in length), and Location into apical only or others. The outcome was the risk of BCR which was calculated with univariable and multivariable regression models and reported as hazard ratio (HR) with 95% confidence interval (CI). RESULTS: The cohort constituted of 1433 men. Majority had ISUP 2 (71.2%) or localized (62%) disease. Men with PSM (n = 506) were at greater risk of BCR when compared to those with negative margins (adjusted HR = 1.52, [CI 1.14-2.04], p = .005). Similar observation was demonstrated for both PSM location subgroups. As for the PSM extent category, only men with unfavourable PSM demonstrated an increase in BCR risk over negative margin (adjusted HR = 1.67, [CI 1.23-2.28], p = .001). CONCLUSIONS: Within this study settings, PSM were generally associated with increased BCR risk. This, however, was not demonstrated in favourable PSM extent cases. Observation rather than active treatment in these men should be considered.