Department of Pathology and Laboratory Medicine, Mount Sinai Hospital and University of Toronto, 600 University Avenue, Toronto, ON, M5G 1X5, Canada.
Breast Cancer Res Treat. 2021 Feb;186(1):99-105. doi: 10.1007/s10549-020-06048-9. Epub 2021 Jan 3.
Fluorescence in situ hybridization (FISH) analysis is recommended for invasive breast carcinomas with equivocal (2+) immunohistochemical expression of human epidermal growth factor receptor 2 (HER2). However, existing guidelines for the retention and storage requirements for HER2 FISH slides vary widely among countries and laboratories.
To determine the degradation rate of HER2 FISH signals, and the optimal retention time and storage conditions for HER2 FISH slides.
Dual-probe HER2 FISH slides from March 2009 to June 2019 were retrieved from the archive to assess the presence, intensity and quantity of the green chromosome enumeration probe 17 (CEP 17) and orange HER2 signals. Per the institutional policy, FISH slides are placed in slide boxes and stored in - 80 °C freezers for up to 4 years, whereas older slides are stored at room temperature.
After excluding HER2 FISH slides that were deemed uninterpretable due to technical issues, a total of 6255 slides were assessed. Slides from 2009 to 2014 were stored at room temperature, while slides from 2015 to 2019 were stored in - 80 °C freezers. Slides stored in freezers showed retention of both the green and the orange signals. Slide stored at room temperature demonstrated significant decrease in the signal retention rate and the loss of signal did not progress in a linear fashion. The CEP17 signal was quenched much faster than the HER2 signal.
Our study is the first to demonstrate HER2 FISH signal degradation with time and slide storage conditions. Storing HER2 FISH slides in a -80 °C freezer allows for retention of both HER2 and CEP17 signals. At room temperature, the signals start to degrade with CEP17 signals lost at a faster rate. The results of the study may be used in official guidelines for storage conditions and retention time for HER2 FISH slides.
荧光原位杂交（FISH）分析被推荐用于免疫组织化学（IHC）检测人表皮生长因子受体 2（HER2）表达为 2+的浸润性乳腺癌。然而，目前各国和实验室之间关于 HER2 FISH 切片的保留和存储要求的指南差异很大。
确定 HER2 FISH 信号的降解率以及 HER2 FISH 切片的最佳保留时间和存储条件。
从 2009 年 3 月至 2019 年 6 月的存档中检索到双探针 HER2 FISH 切片，以评估绿色染色体计数探针 17（CEP17）和橙色 HER2 信号的存在、强度和数量。根据机构政策，FISH 切片被放置在切片盒中，并储存在-80°C 的冰箱中，最长可达 4 年，而较旧的切片则储存在室温下。
在排除由于技术问题而被认为无法解释的 HER2 FISH 切片后，共评估了 6255 张切片。2009 年至 2014 年的切片储存在室温下，而 2015 年至 2019 年的切片储存在-80°C 的冰箱中。储存在冰箱中的切片保留了绿色和橙色信号。储存在室温下的切片显示信号保留率显著下降，信号丢失并没有呈线性趋势。CEP17 信号的猝灭速度远快于 HER2 信号。
本研究首次证明了 HER2 FISH 信号随时间和切片存储条件的降解。将 HER2 FISH 切片储存在-80°C 的冰箱中可以保留 HER2 和 CEP17 信号。在室温下，信号开始降解，CEP17 信号的丢失速度更快。研究结果可用于 HER2 FISH 切片存储条件和保留时间的官方指南。
