Department of Clinical and Molecular Medicine, Faculty of Medicine and Health Sciences, Norwegian University of Science and Technology, Erling Skjalgssons gate 1, Trondheim, Norway.
Department of Pathology, St. Olav's Hospital, Trondheim University Hospital, Trondheim, Norway.
Diagn Pathol. 2022 May 6;17(1):45. doi: 10.1186/s13000-022-01225-4.
In breast cancer (BC) Ki-67 cut-off levels, counting methods and inter- and intraobserver variation are still unresolved. To reduce inter-laboratory differences, it has been proposed that cut-off levels for Ki-67 should be determined based on the in-house median of 500 counted tumour cell nuclei. Digital image analysis (DIA) has been proposed as a means to standardize assessment of Ki-67 staining in tumour tissue. In this study we compared digital and visual assessment (VA) of Ki-67 protein expression levels in full-face sections from a consecutive series of BCs. The aim was to identify the number of tumour cells necessary to count in order to reflect the growth potential of a given tumour in both methods, as measured by tumour grade, mitotic count and patient outcome.
A series of whole sections from 248 invasive carcinomas of no special type were immunohistochemically stained for Ki-67 and then assessed by VA and DIA. Five 100-cell increments were counted in hot spot areas using both VA and DIA. The median numbers of Ki-67 positive tumour cells were used to calculate cut-off levels for Low, Intermediate and High Ki-67 protein expression in both methods.
We found that the percentage of Ki-67 positive tumour cells was higher in DIA compared to VA (medians after 500 tumour cells counted were 22.3% for VA and 30% for DIA). While the median Ki-67% values remained largely unchanged across the 100-cell increments for VA, median values were highest in the first 1-200 cells counted using DIA. We also found that the DIA100 High group identified the largest proportion of histopathological grade 3 tumours 70/101 (69.3%).
We show that assessment of Ki-67 in breast tumours using DIA identifies a greater proportion of cases with high Ki-67 levels compared to VA of the same tumours. Furthermore, we show that diagnostic cut-off levels should be calibrated appropriately on the introduction of new methodology.
在乳腺癌（BC）中，Ki-67 的截断值、计数方法以及观察者内和观察者间的差异仍然没有得到解决。为了减少实验室间的差异，有人建议 Ki-67 的截断值应该基于 500 个计数的肿瘤细胞核的内部中位数来确定。数字图像分析（DIA）已被提议作为标准化评估肿瘤组织中 Ki-67 染色的一种手段。在这项研究中，我们比较了连续系列 BC 的全切片的数字和视觉评估（VA）Ki-67 蛋白表达水平。目的是确定在两种方法中计数多少肿瘤细胞以反映给定肿瘤的生长潜力，这是通过肿瘤分级、有丝分裂计数和患者预后来衡量的。
对 248 例非特殊类型浸润性癌的全切片进行 Ki-67 的免疫组织化学染色，然后分别用 VA 和 DIA 进行评估。使用 VA 和 DIA 在热点区域计数 5 个 100 个细胞增量。使用 Ki-67 阳性肿瘤细胞的中位数来计算两种方法中低、中、高 Ki-67 蛋白表达的截断值。
我们发现 DIA 比 VA 检测到的 Ki-67 阳性肿瘤细胞的百分比更高（计数 500 个肿瘤细胞后的中位数分别为 VA 22.3%和 DIA 30%）。虽然 VA 的 Ki-67%中位数值在 100 个细胞增量中基本保持不变，但 DIA 在前 1-200 个细胞计数中的中位数值最高。我们还发现，DIA100High 组鉴定出的组织学分级 3 肿瘤比例最大，为 70/101（69.3%）。
我们表明，与同一肿瘤的 VA 相比，使用 DIA 评估乳腺肿瘤中的 Ki-67 可识别出更高比例的 Ki-67 水平较高的病例。此外，我们表明，在引入新方法时，应适当校准诊断截断值。
