Biopsy confirmation of metastatic breast cancer: interim results of a prospective biopsy study

Objective

Decisions about systemic treatment of women with metastatic breast cancer are often based on oestrogen receptor (ER), progesterone receptor (PgR), and HER2/neu status of the primary tumour. The present study prospectively investigated concordance in receptor status between primary tumour and distant metastases at various stages of progression and assessed the impact of any discordance on patient management.

Methods

Biopsies of suspected metastatic lesions were obtained from patients and were analysed for ER/PgR and HER2/neu. The receptor status of metastases was compared with the primary tumour. The treating physician completed questionnaires before and after biopsy to determine whether the biopsy resulted in a change to the treatment plan.

Results

Eighty women were enrolled and 70 of them underwent biopsy. Of these, 43 (61%) were newly diagnosed with metastatic disease, 10 (14%) had received one line of treatment in the metastatic setting and 17 (24%) had received two or more lines of treatment in the metastatic setting. Fifty-six samples were sufficient for analysis; of these, 4/56 biopsies (7%) showed benign disease and one biopsy (2%) confirmed a different malignancy (idolent lymphoma). Changes in hormone receptor status were observed in 34% and in HER2/neu status in 5% of women. Loss of PgR was the most common change in hormone receptor status (29%). All changes in HER2/neu involved gain of receptor. Biopsy results led to a change of management in 9/70 patients (13%). Patients with newly diagnosed metastatic disease were more likely to show discordance than those previously treated in the metastatic setting. Triple-negative tumours were least likely to show discordance.

Conclusion

This prospective study demonstrates the presence of substantial discordance in receptor status between primary tumour and metastases. The number of patients needed to biopsy to alter management is 7.8. Tissue confirmation should be considered in patients with clinical or radiological suspicion of metastatic recurrence.