Abstract P1-02-02: Receptor discordance in breast cancer recurrence: Is re-biopsy a necessity?

Abstract

Abstract Background: Decision making on systematic treatment of patients with metastatic breast cancer is based on features like estrogen receptor (ER), progesterone receptor (PgR), and HER2 status assessed on the primary tumor. Recent prospective studies have investigated discordance in receptor status between the primary and metastatic tumor. We evaluated the discordance of receptor status between the primary and metastatic tumor and assessed the impact of re-biopsy on patient management. Methods: In breast cancer patients who underwent surgical resection of primary tumor and re-biopsy of metastatic tumor at Aichi Cancer Center hospital, we examined the discordance of ER status, PgR status, and HER2 status between the primary and metastatic tumor. For sampling of metastases, core needle biopsy (CNB), trans-bronchial lung biopsy (TBLB), or surgical resection was performed. And fine-needle aspiration biopsy was not used. The ER and PgR status were assessed using Allreds scoring system by IHC. These statuses were categorized as positive when the total score was more than two. HER2 expression status was tested by IHC and FISH. HER2 3+ by IHC, or 2+ and FISH positive were judged as HER2 positive. Results: 48 patients underwent re-biopsy from 2003 to 2012. Twenty-eight were loco-regional (local: 25, Supraclavicular: 2, Axilla: 1) and 21 were distant (Lung: 14, Liver: 6, Bone: 1). Discordance in ER, PgR, or HER2 between the primary and metastatic tumor were 6.2% (3/48), 16.7% (8/48), and 4.2% (2/48), respectively. One patient had discordance on re-biopsy with initial triple negative primary tumor (1/5, 20%). 11/48 patients (22.9%) changed the molecular subtype (Group A), and 37/48 patients (77.1%) did not change (Group B). Time to recurrence (TTR) was significantly longer in Group A than Group B (82.3 months vs 51.2 months, p = 0.04). No significant difference in re-biopsy techniques (CNB and TBLB vs surgical resection), metastatic lesions (loco-regional vs distant), and adjuvant therapy were observed between Group A and Group B. Conclusions: Our results show the low level of discordance for ER and HER2 between the primary and metastatic tumor. But re-biopsy should be considered in the patients with long TTR, since it is likely to impact treatment choice. Further study is needed to determine the value of re-biopsy. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P1-02-02.