Differences in the expression of 4 progesterone receptor antibodies EP2, SP2, 1E2, and 16 in non-specific invasive breast cancers

Abstract

Objective To detect the expression of 4 progesterone receptor (PR) antibodies (EP2, SP2, 1E2, and 16) in non-specific invasive breast cancer (NSIBCs) and identify the optimal antibody for PR analysis and treatment planning for NSIBCs. Methods Immunohistochemistry was used to detect the expression of the 4 PR antibodies in a tissue microarray consisting of 195 tissue specimens of NSIBCs, and their constituent ratios with the expression of estrogen receptor (ER), the percentages of stained cells, staining intensity, Allred score (A-score) and consistency were compared. Results The constituent ratios of the 4 PR antibodies with ER (ER±/PR±) did not differ significantly in the 195 cases of NSIBCs (P>0.05). Regardless of the status of ER expression, the cases showed high rates of positivity or negativity for all the 4 PR antibodies at the same time (81.54%~90.77%) with good consistencies among the 4 antibodies (κ=0.634~0.804). Further analysis of the average number of stained cells, percentage of positive cells, staining intensity, and A-score of the 4 PR antibodies showed that all these indicators were significantly higher for 1E2 than for EP2, SP2, and 16 (P 0.05). Conclusion 1E2 has a higher positivity rate and expression intensity in NSIBCs than EP2, SP2 and RP16, and thus can serve as an ideal PR antibody for clinical pathology tests.

Keywords

• non-specific invasive breast cancers
• immunohistochemical staining
• progesterone receptor
• estrogen receptor