Comparative Analysis of Different Counting Methodologies for Ki-67 in Pancreatic Neuroendocrine Tumors
Pelin Bagci, Nobuyuki Ohike, Nevra Dursun, Kee-Taek Jang, Takuma Tajiri, Olca Basturk, So Yeon Kong, Leslie Ducato, Michelle Reid, Volkan Adsay. Emory University, Atlanta; Showa University, Tokyo, Japan; MSKCC, New York
Background: Ki-67 labeling index is now one of the 2 parameters in the classification of pancreatic NETs in the WHO-2010 classification. However, in adapting this into daily practice, it becomes clear that there are serious challenges in the counting methodologies.
Design: Ki-67 immunohistochemical staining was performed on full sections from 21 NETs, and percentage of the tumor cells stained was counted by 4 different methods by 3 observers: 1) “Eye-balling”, 2) "Eye-counting" through the microscope, 3) Automated counting, 4)Manual counting on camera-captured/printed image of the hot spot.
Results: Considering the balance of accuracy, practicality, and reproducibility, the method that was found to be by far the most preferable (Table) was the manual counting on camera-captured/printed image.
|Impact on turnaround time||Average time it takes (minutes)||Practicality||Accuracy||Miscounting of non-target cells||Interobserver agreement (Pearson's correlation)||Additional Cost|
|Eye-counting through microscope||None||6||Low||High||Unlikely||R=32%||None|
|Manual counting on camera captured/printed image of the hot spot||Minimal (depending on accessibility of a camera/printer setup)||13||Very high||Highest||Unlikely||R=43%||Printer + camera $5,400|
|Automated||Highest (depends on the technician availability)||5||Low (accessibility issues)||Moderate||Very likely||N/A||Image analyzer $150,000|