Fixation time does not affect the expression of estrogen receptor

Area of Science:

• Oncology
• Pathology
• Biochemistry

Background:

• Estrogen receptor (ER) status is crucial for breast cancer diagnosis and treatment decisions.
• Immunohistochemistry (IHC) is the standard method for ER detection.
• Formalin fixation is a critical pre-analytical variable that may affect IHC results.

Purpose of the Study:

• To evaluate the impact of varying formalin fixation durations (1, 3, 6, and 9-10 hours) on estrogen receptor expression in invasive breast cancer.
• To assess if fixation time influences the intensity and percentage of ER-positive cells detected by IHC.

Main Methods:

• Pilot study involving 10 invasive breast cancer cases.
• Tissue samples were fixed in 10% buffered formalin for 1, 3, 6, and 9-10 hours.
• Immunohistochemical analysis was performed using three different anti-ER antibodies (SP1, 6F11, 1D5).

Main Results:

• No statistically significant differences were observed in the intensity of staining or the percentage of ER-positive cells across different fixation times.
• The choice of antibody (SP1, 6F11, 1D5) did not alter the findings regarding fixation time.
• Results were consistent across all tested fixation durations.

Conclusions:

• Formalin fixation times ranging from 1 to 9-10 hours do not appear to significantly affect estrogen receptor expression as determined by immunohistochemistry in high-expressing breast tumors.
• These findings suggest that current fixation protocols within this range are reliable for ER assessment in routine practice.
• Further studies with larger cohorts and diverse tumor types may be warranted to confirm these results.