Intratumoral Heterogeneity in Breast Cancer: A Comparison of Primary and Metastatic Breast Cancers

Intratumoral heterogeneity presents challenges in the management of cancer. To gain deeper insight in intratumoral heterogeneity at different levels and tumor sites for common biomarkers in breast cancers, this report examines seven cases of invasive breast cancer with multiple axillary nodal metastases and/or recurrences for immunohistochemical expression of estrogen receptors, progesterone receptors, human epidermal growth receptor 2, and Ki67 on all tissue blocks in both primary and metastatic tumors.