Abstract
Pre-analytic steps are important for the immunohistochemical study as in the case of breast cancers. The initial process is the fixation in which the 10% neutral buffered formalin (NBF) is recommended. 10% formalin is less expensive and easier to prepare but its effect on the immunostaining is controversial. The aim of this study was to compare the effect of 10% formalin with 10% NBF on oestrogen receptor (ER) and Ki67 immunostains in breast cancer specimens. Thirty breast cancer specimens were collected. Each tumour was bisected and separately fixed in 10% formalin and 10% NBF, processed, and immunostained with ER and Ki67. Whole slides were scanned and evaluated by digital image analysis. A semiquantitative H-score was determined. No significant differences, both the percentage and H-score, of the ER- and Ki67-positive cells were found between breast cancer specimens fixed in 10% formalin and 10% NBF. In conclusion, 10% formalin could be used as a fixative for immunohistochemical study for breast biomarkers. The unbuffered fixative is less expensive and easier to prepare, compared to 10% neutral buffered formalin. Additional study is reasonable to evaluate the effect of 10% formalin to the quality of nucleic acid.