Should liver metastases of breast cancer be biopsied to improve treatment choice?

CRA1008 Background: Decision making on systemic treatment of women with metastatic breast cancer is based on features like estrogen receptor (ER), progesterone receptor (PgR), and HER2 status assessed on the primary tumor. We evaluated the concordance of receptor status between primary tumor and liver metastases (mts) and its impact on treatment choice. METHODS We retrospectively analyzed a database including ultrasound guided liver biopsies performed from 1995 to 2008. All tissue samples, both from primary tumor and liver mts, were analyzed for ER, PgR and HER2 status. Clinical and biological data were obtained from medical charts. Differences between proportions were evaluated using the Pearson chi-square test. RESULTS We identified 255 consecutive patients (pts) with matched primary and liver tissue samples. Median time from primary diagnosis to liver biopsy was 3.4 years (range 0-18.3 years). Changes in ER status were observed in 41/255 pts (16.0%). 16/58 pts (27.6%) changed from ER-negative to ER-positive and 25/197 pts (12.7%) changed from ER-positive to ER-negative (p=0.0066). Changes in PgR status were observed in 76/255 pts (29.8%). 18/91 pts (19.8%) changed from PgR-negative to -positive and 58/164 pts (64.6%) from PgR-positive to PgR-negative (p <0.0001). 12/52 pts (23.1%) changed from ER- and PgR-negative to ER- or PgR-positive (group A) and 27/203 pts (13.3%) changed from ER- or PgR-positive to ER- and PgR-negative (group B) (p=0.087). In the group A the treatment of 4/12 pts (33.3%) was changed after biopsy: 2/4 started endocrine treatment (HT) and 2/4 stopped it. In group B the treatment of 18/27 pts (66.6%) was changed after biopsy: 17/18 stopped HT. Changes in HER2 status were observed in 22/167 pts (13.1%): 6/116 pts (5.1%) changed from HER2-negative to HER2-positive and 16/51 pts (31.4%) changed from HER2-positive to negative (p≤0.0001). In this group pts started and/or stopped a trastuzumab containing treatment after biopsy. CONCLUSIONS There was a discordance in receptor status between primary tumor and liver mts, which led to change in therapy for 48/255 of pts (18.8%). Biopsy of metastases for reassessment of biological features should be considered in all pts when safe and easy to perform, since it is likely to impact treatment choice. No significant financial relationships to disclose.