Abstract
BackgroundPositive surgical margin (PSM) is a predictor of biochemical recurrence (BCR) following radical prostatectomy (RP). Attempts to stratify PSM based on linear length, Gleason score, location and number have failed to add to predictive models using margin status alone. We evaluated the prognostic significance of Ki-67 expression in this setting.MethodsImmunohistochemical staining for Ki-67 was done on prostatectomy specimens from 117 patients who had a PSM. Ki67 expression was measured at the margin and in the index lesion. Patients were dichotomized based on Ki-67 expression into three groups. Group 1 with no Ki-67 expression, Group 2 with Ki-67 ≤ 2%, and Group 3 with Ki-67 ≥ 3%.To eliminate the impact of the adjuvant treatment (AT) on the outcome, data were analyzed by the Cox proportional hazards in which AT was Considered as a time-dependent covariate.ResultsThe discordance rate of Ki-67 expression between matched index lesion and margin specimens was 44/117 (37.6%). There was a trend for higher risk of BCR (HR:2.06, (0.97–4.43), P = 0.06) in patients expressing high Ki67 at the surgical margin although this was not statistically significant. However High Ki-67 expression in the index lesion was an independent predictive factor for BCR in this subset of patients. (HR:4, (1.64–9.80), P = 0.002).ConclusionHigh Ki67 expression in the index prostate cancer lesion is an independent predictor of BCR in patients with positive surgical margin following radical prostatectomy. Our findings need to be validated in a larger cohort.
Highlights
Positive surgical margin (PSM) is a predictor of biochemical recurrence (BCR) following radical prostatectomy (RP)
High Ki67-LI was an independent predictor of increased disease specific mortality and biochemical recurrence in primarily intermediate-risk prostate cancer patients treated with RT or Radical prostatectomy [4, 5]
The Ki-67 index was assessed independently by the same two pathologists using the following method: 1-the tumor area was screened to identify the foci with the highest nuclear staining; 2-these foci were divided into quadrants and examined at high power magnification (400×); 3- tumor nuclei were counted in each quadrant, and the percentage of positive tumor nuclei was determined
Summary
Positive surgical margin (PSM) is a predictor of biochemical recurrence (BCR) following radical prostatectomy (RP). Radical prostatectomy (RP) is still the most common treatment for localized prostate cancer and has benefited from several refinements in surgical technique and technological advancements. A true measure of the oncological quality of RP remains the positive surgical margin which is considered an adverse prognostic feature that can predict biochemical recurrence (BCR). Not strongly expressed in prostate cancer cells, Shahait et al BMC Urology (2018) 18:13 several studies have shown its potential role in predicting BCR and even prostate cancer-specific mortality. High Ki67-LI was an independent predictor of increased disease specific mortality and biochemical recurrence in primarily intermediate-risk prostate cancer patients treated with RT or Radical prostatectomy [4, 5]. Tollefson et al found that each 1% increase in Ki-67 expression was associated with a 12% increased risk of prostate cancer-specific death [6]
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