Abstract P2-04-08: Accuracy of estrogen receptor, progesterone receptor, HER2 Status and Ki67 labeling index between core needle and surgical excisional tumour in 910 patients with breast cancer

Abstract

Abstract Purpose Accurate determination of ER, PgR, HER2 status and Ki67 labeling index was very important in making decision for adjuvant and neoadjuvant treatment for patients with breast cancer. However discordance of ER, PgR, HER2 status and Ki67 labeling index (Ki67-LI) between core needle biopsy (CNB) and surgical specimens (SSp) varied among reported studies. The aim of the present study was to compare the accuracy of CNB with that of SSp for ER, PgR,HER-2 status, Ki67-LI detection in breast cancer. Patients and methods All patients diagnosed with an early breast cancer in our Cancer Center Hospital between January 2005 and May 2014 was included but exclusion criteria of patients with large tumour requiring neoadjuvant chemotherapy. All CNB were performed under ultrasound guidance, with at least four 14-gauce core biopsies being obtained for pathological examination. ER, PgR, HER-2 status and Ki67-LI were assessed in CNB and in SSp. ER and PgR were determined by Immunohistochemistry (IHC). The cut points for ER and PgR positive was10%. The cut point for Ki67-LI high expression was 20%. HER2 was determined by IHC and scored from 0 to 3+. FISH analysis was carried out in HER2 2+ cases and in discordant cases. Results A total of 910 patients were assessed. CNB can be used with confidence for ER and HER2 determination. Rates for sensitivity, specificity, negative predictive value and positive predictive value for CNB compared with SSp are 99.3%,95.6%,97.2%,98.5% for ER, 94.5%,81.8%,88.2%,90.7% for PgR ,93.0%,99.1%,99.6%,93.9% for HER2, and 87.7%,69.8%,81.1%,79.4% for Ki67-LI, respectively. Specially, the most impact factor of discordance for Ki67-LI and HER2 is Tumour size and that for ER and PgR is lobular carcinoma. Conclusion CNB can be used with confidence for ER and HER2 determination. For PgR and Ki67-LI due to substantial discordance results from CNB should be used with caution. Citation Format: Rikiya Nakamura, Naohito Yamamoto, Yoshiyuki Itookubo, Ayako Nakagawa, Makiko Itami. Accuracy of estrogen receptor, progesterone receptor, HER2 Status and Ki67 labeling index between core needle and surgical excisional tumour in 910 patients with breast cancer [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P2-04-08.