B11
Is tissue the issue? The impact of biopsy confirmation of metastases in breast cancer
Eitan Amir, Orit Freedman, Christine Simmons, Naomi Miller, William Geddie, Aurora De Borja, Htway Maung, David Gianfelice, Mark Clemons
Princess Margaret Hospital, Toronto, Canada
Aim
Decisions about systemic treatment of women with metastatic breast cancer are often based on estrogen receptor (ER), progesterone receptor (PgR), and HER2/neu status of the primary tumour. This 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.
Method
Biopsies of suspected metastatic lesions were obtained from patients and analyzed for ER/PgR and HER2/neu. Receptor status of metastases was compared to 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
One hundred women were enrolled and 88 of them underwent biopsy. Of these 48 (55%) were newly diagnosed with metastatic disease, 14 (16%) had received one line of treatment in the metastatic setting and 26 (30%) had received 2 or more lines of treatment in the metastatic setting. 75 samples were sufficient analysis; of these 4/75 biopsies (5%) showed benign disease and one biopsy (1%) confirmed a different malignancy (indolent lymphoma). Changes in hormone receptor status were observed in 39% of women while HER2/neu showed 5% discordance. Loss of PgR was the most common change in hormone receptor status (28%). Three patients gained and one patient lost HER2/neuexpression. Biopsy results led to a change of management in 10/88 patients (11%). Patients with newly diagnosed metastatic disease were more likely to show discordance than those previously treated in the metastatic setting. Among triple negative tumours were no changes in receptor expression.
Conclusion
This prospective study demonstrates the presence of substantial discordance in receptor status between primary tumour and metastases. The number needed to biopsy to alter immediate management is 8.8, although biopsy information could also be useful in planning later treatment. Tissue confirmation should therefore, be considered in patients with suspicion of metastatic recurrence or progression.
