The effects of under 6 hours of formalin fixation on hormone receptor and HER2 expression in invasive breast cancer: a systematic review.

A systematic review of the literature was performed to identify whether minimum formalin fixation time may be reduced for reliable immunohistochemical assessment of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2). PubMed, EMBASE, and the Cochrane Library were systematically searched for studies addressing effects of brief tissue fixation (<6 hours) on the analysis of ER, PR, or HER2 expression in patients with breast cancer. Five publications reported effects of brief fixation on ER, PR, or HER2 expression. Four studies showed similar receptor expression of short fixation compared with recommended fixation time (6-72 hours). One publication found that a minimum fixation time of 6 to 8 hours is necessary for reliable ER results. Available data on the effect of brief fixation on receptor status are limited. However, brief fixation of very highly expressing breast cancers does not seem to alter ER, PR, and HER2 status. Nevertheless, scoring inconsistencies have been observed. Further research is required in larger study populations with more low-expressing cases for future validation.