Molecular Biomarker Discordance between Primary and Recurrent/Metastatic Breast Cancer

A clinical practice guideline for patients with a history of breast cancer. The guideline examine the use of biopsies and retesting of estrogen receptor (ER), progesterone receptor (PR) and HER2-neu receptor (HER2) to determine recurrence or metastases. Outcomes of interest include progression-free and overall survival.