2018 Volume 57 Issue 2 Pages 109-113
Objective : We conducted a study to validate the optimum fixation time for receptor analysis in breast cancer cell blocks.
Study Design : Cell samples from excised breast cancers were fixed in 10% buffered formalin and embedded in paraffin. The fixation time varied between two hours and 120 hours. The following tests were performed : immunostainings for estrogen receptor (ER) (10 samples), progesterone receptor (PgR) (10 samples) and HER2 protein (21 samples), and the HER2 dual in situ hybridization (DISH) assay (15 samples). The results of the analysis for hormone receptors were judged by counting the number of positively stained cells per 100 cancer cells. For the HER2 test, we used the criteria described in the ASCO/CAP guideline for preparing the tissue sections.
Results : The results of the analyses for ER and PgR, as well as the results of HER2 DISH, remained stable in the fixation time range of two hours to 120 hours. However, weak results of HER2 protein staining were obtained in three samples that were fixed for less than six hours and one sample that was fixed for more than 48 hours.
Conclusion : The recommended fixation time for receptor analysis on formalin-fixed breast cancer cell blocks is between six hours and 48 hours.
