Endocrine Abstracts

Objective: Digital pathology is the process of scanning conventional slides and then digitally stitching consecutive images into digital slides that can be viewed, managed, and analyzed on a computer monitor. In this study, we evaluated the area of metastatic foci in cervical lymph node (LN) metastasis in application of digital pathology and prognostic implication for predicting structural recurrence in patients with papillary thyroid cancer (PTC).

Methods: This study included 316 patients with PTC with LN metastasis who underwent total thyroidectomy between 2010 and 2020 at the Asan Medical Center in Korea. Initially, we reviewed the tumor cells in metastatic LNs by measuring the longest diameter from the single screenshots of histological images captured through a microscope’s optics. Then we measured the longest diameter and the largest area using the whole slide imaging (WSI) scanner. Progression-free survival (PFS) were evaluated based on the diameter or area of metastatic foci in LNs using cut-off values by the Contal and O’Quigley methods.

Results: The median age of the patients was 45.6 years and 90 of 316 (28.5%) were male. The median primary tumor size was 17.0 mm and the median longest diameter of LNs were 10.0 mm (IQR 6.0-15.3), 10.8 mm (IQR 7.0-16.6) in tradition and digital pathology, respectively. The medain largest area was 41.6 mm² (IQR 18.5-121.1). There was a significantly positive correlation with the longest diameter between traditional and digital pathology (R = 0.928, P <0.001). The optimal cut off values for predicting structural recurrent disease were 8.0 mm in both traditional pathology (P=0.009) and digital pathology (P=0.016). There were significant differences in the PFS based on the optimal cut off values in traditional and digital pathology (P=0.006 and P=0.002, respectively). The results of correlation analysis showed a significant quadratic relationship between diameter and area, with R sqaure values of 0.891 (P<0.001) in digital pathology compared to 0.727 (P<0.001) in traditional pathology. The cut-off value of area was 35.6 mm² (P=0.005) and there was a significant difference in PFS by this cut-off value (P=0.015).

Conclusions: There was no discernible difference in measuring the longest diameter of metastatic LNs between traditional and digital pathology. Digital pathology has an advantage to easily measure the area of metastatic foci, however this measurement was not more effective than traditional method in predicting prognosis of patients with PTC.