Digital versus light microscopy assessment of surgical margin status after radical prostatectomy

Area of Science:

• Uropathology
• Surgical Pathology
• Digital Pathology

Background:

• Positive surgical margin (PSM) is a critical prognostic factor after radical prostatectomy.
• Current methods for assessing PSM, including linear extent and focal/non-focal classification, lack standardized measurement and cut-off points.
• The clinical significance of PSM measurement requires further objective evaluation.

Purpose of the Study:

• To evaluate the utility of digital microscopy (DM) for objective measurement of PSM.
• To compare PSM assessment using DM versus conventional light microscopy (LM).
• To determine the prognostic significance of DM-based PSM measurements for biochemical recurrence (BR).

Main Methods:

• Analysis of PSM status in 107 laparoscopic radical prostatectomies using both DM and LM.
• Comparison of PSM detection rates and measurements between DM and LM.
• Correlation of linear PSM measurements and the number of positive blocks with BR using Receiver Operating Characteristic (ROC) analysis and survival analysis.

Main Results:

• DM identified three additional PSM cases, though overall differences between DM and LM were not statistically significant (p=0.220).
• Mean linear PSM measurements by both LM (p=0.002) and DM (p=0.001) correlated with BR.
• DM-derived cut-off (3.2 mm) was a significant predictor of BR-free survival, unlike LM (3.5 mm). A cut-off ≤3 mm was associated with BR for both LM (p=0.023) and DM (p=0.001). The number of blocks with PSM also correlated significantly with BR (p<0.001).

Conclusions:

• Digital microscopy provides more accurate PSM measurements than light microscopy.
• Reporting PSM linear extent (≤3 mm vs. >3 mm, with DM cut-off of 3.2 mm) or the number of positive blocks (1 vs. ≥2) can serve as important prognostic indicators after radical prostatectomy.
• DM enhances the prognostic value of PSM assessment in predicting biochemical recurrence.