Abstract 5243: Prognostic value of nuclear and non-nuclear estrogen receptor expression by immunohistochemistry with phosphor-integrated dots in hormone receptor-positive early breast cancer

Abstract

Abstract Background: Estrogen receptor α (ERα) is associated to cell proliferation and survival through genomic (nuclear) and non-genomic (non-nuclear) signaling pathway. Endocrine therapy is the most effective therapies for patients with hormone receptor(HR) positive breast cancer. Recent progress shows that both nuclear and non-nuclear crosstalk was considered to contribute to endocrine resistance. Clinically, ERα is predominantly observed using immunohistochemistry(IHC) as a nuclear protein while unable to detect nuclear and non-nuclear ERα separately. Our group recently created new fluorescent nanoparticles called phosphor-integrated dots (PIDs). PIDs has extremely brightness so that it could be double stained with hematoxylin and quantitated without influence. In addition, the localization of biomarker protein can be visualized and analyzed on cell as PIDs score by this method. Methods: 65 HR+/HER2- breast cancer patients from 2001 to 2003 who treated with postoperative endocrine therapy were selected in this study. Expression levels of total ERα, nuclear-ERα, non-nuclear-ERα, progesterone receptor (PR) was examined by IHC with PIDs. Nuclear-ERα was recognized by double staining using hematoxylin. IHC with DAB was carried out to analyze the expression levels of ER and PR and H score was automatically calculated. In addition, PIDs score of non-nuclear-ERα can be calculated through PIDs score of total ERα and nuclear-ERα by PID analyzer. Optimal cutoff value of PIDs score of each receptor to predict survival were derived and independently tested. The correlation among every clinical characteristic and pathological feature was examined. Result: PIDs score of total ERα(χ2=5.17, p=0.023) and nuclear-ERα is negative correlated with relapse (χ2=6.46, p=0.011), ratio of non-nuclear-ERα to total ERα is positive correlated with relapse (χ2=5.82, p=0.016).The cutoff value as 37.46 of nuclear-ERα PIDs score was statistically proved significant for predicting disease-free survival(DFS) (log-rank p=0.020).We also found that cutoff value as 0.32 which represents ratio of non-nuclear-ERα PIDs score to total ERα PIDs score was statistically proved significant for predicting DFS (log-rank p=0.022). H score of ER, PR and PIDs score of non-nuclear-ERα, PR has no predictive value for recurrence. Conclusion: Our result demonstrates that nuclear-ERα PIDs score obtain a higher prognostic value than that of total-ERα PIDs score and H score detected by DAB-IHC. Ratio of non-nuclear-ERα to total ERα may play a role of prognostic factor in HR positive breast cancer. Citation Format: Zhaorong Guo, Hiroshi Tada, Narufumi Kitamura, Yoh Hamada, Shin-ichi Hayashi, Noriaki Ohuchi, Kosuke Gonda, Takanori Ishida. Prognostic value of nuclear and non-nuclear estrogen receptor expression by immunohistochemistry with phosphor-integrated dots in hormone receptor-positive early breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5243.