Molecular Interrogation of Estrogen-Receptor–Positive Breast Cancer

In the era of precision medicine, the ability to order molecular profiling of tumors offers the possibility of determining “the right therapy for the right patient at the right time.” To that end, investigators have now evaluated the evolution of mutational, copy number, and gene expression profiles in 182 patients with estrogen-receptor (ER) –positive breast cancer patients treated in Belgium between 1982 and 2008. All patients had disease recurrence after receiving adjuvant therapy for early-stage disease.

Metastatic samples were available for 48% of patients. ER, HER2, Ki67, and PTEN status was determined for all patient samples. Tumor material was evaluated for 120 hotspot mutations in 11 cancer genes using a polymerase chain reaction (P…