Abstract P1-13-03: Is Bone Biopsy of Metastatic Sites Useful in Advanced Breast Cancer Management?

Abstract

Abstract Background: Biopsies of metastatic sites are not recommended in clinical practice to evaluate changes in biological features in advanced breast cancer (ABC) women. We assessed discordance in expression levels for estrogen receptor (ER), progesterone receptor (PgR) and epidermal growth factor receptor 2 (HER2), between primary tumor and bone metastases and its clinical impact on patient management. Material and Methods: We retrospectively analyzed 109 ABC patients (pts) underwent computed tomography guided bone biopsy at the European Institute of Oncology in Milan, Italy, from 1997 to 2009. Data on ER and PgR status [positive if ≥1% by immunohistochemistry (IHC)] and on HER2 status (positive if IHC3+ and/or FISH amplified), both primary tumor and bone metastases were collected. Fisher and McNemar's test were used for statistical analysis. Results: Median time from primary diagnosis to bone biopsy was 4.2 years (range 0-18.9). Overall discordance rate (ODR) in ER expression was 20.5% (95% CI: 13.4%-29.5%): 3/7 pts (42.9%) shifted from ER negative to positive and 19/100 pts (19%) from ER positive to negative [p=0.0006]. ODR in PgR expression was 43.9% (95% CI: 34.3%-53.8%): 4/21 pts (19%) changed from PgR negative to positive and 43/86 pts (50%) from PgR positive to negative [P<0.0001]. ODR in HER2 status was 6.9% (95% CI: 2.6%-14.6%): 4/78 pts (5.1%) changed from HER2 negative to positive and 2/8 pts (25%) turned from HER2 positive to negative [p=0.41]. Thirteen out of 21 pts (61.9%) with discordant ER status and 23/77 pts (29.8%) with concordant ER status [p=0.01] changed endocrine therapy; there were no differences in chemotherapy [p=0.80]. Four out of 6 pts (66.6%) with discordant HER2 status and 6/72 pts (8.3%) with concordant HER2 status changed immunologic therapy [p=0.002], 3/6 pts (50%) started trastuzumab and 1/6 patient (16.6%) stopped it; there were no differences in chemotherapy [p=0.68]. All pts well tolerated the invasive procedure, requiring only local analgesia. Discussion: Our analysis showed that receptor profile may significantly change between primary breast cancer and bone metastases, with relevant impact on therapy. Bone biopsy might be useful and should be considered in selected cases to optimize therapeutic choices. Large prospective trials are needed to investigate these outcomes. Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P1-13-03.