SUMMARY: Breast cancer is the most common cancer among women in the US and about 1 in 8 women (12%) will develop invasive breast cancer during their lifetime. Approximately, 246,660 new cases of invasive breast cancer will be diagnosed in 2016 and 40,450 women will die of the disease. Patients with early stage breast cancer often receive adjuvant therapy. Tumor biomarker assays have become an integral part of the treatment decision making process along with clinical and histologic tumor characteristics, further enabling customized care for patients with early-stage invasive breast cancer. A multitude of biomarker assays are presently available for the practicing Health Care Provider. Choosing the appropriate biomarker assay for a given patient can be a daunting task and the ASCO guidelines set forth herein, were developed by an expert panel based on systematic reviews, meta-analyses, randomized controlled trials, prospective-retrospective studies, and prospective comparative observational studies, published from 2006 through 2014. These guidelines are only applicable for patients with newly diagnosed, non-metastatic, primary breast cancer, to prognosticate and predict outcomes but they do not however comment on the choice of specific treatment or regimens based on recurrence score. Treatment decisions should take into consideration disease stage, comorbidities and patient preferences. Even though several tests are now recommended in the guidelines, only one test should be used to guide therapy for an individual patient.
Two important questions were addressed by these guidelines – This edition (Part 1) addresses the first Clinical Question
Clinical Question 1: For women with early-stage invasive breast cancer and with known Estrogen receptor/Progesterone receptor and HER2 status, which other biomarkers have demonstrated clinical utility to guide decisions on the need for adjuvant systemic therapy?
Oncotype DX
If a patient has ER/PR positive, HER2 negative, node negative breast cancer, the Oncotype DX 21-gene recurrence score may be used to guide decisions on adjuvant systemic therapy. It should not be used in patients with ER/PR positive, HER2 negative, node positive disease. It should not be used in patients with HER2 positive or triple negative disease.
PAM50 Risk of Recurrence Score
If a patient has ER/PR positive, HER2 negative, node-negative breast cancer, the PAM50 Risk of Recurrence score may be used in conjunction with other clinicopathologic variables to guide decisions on adjuvant systemic therapy. It should not be used in patients with ER/PR positive, HER2 negative, node-positive disease. It should not be used in patients with HER2 positive breast cancer and those with triple-negative breast cancer to guide decisions on adjuvant systemic therapy.
EndoPredict
If a patient has ER/PR positive, HER2 negative, node-negative breast cancer, EndoPredict 12-gene risk score may be used to guide decisions on adjuvant systemic therapy. It should not be used in patients with ER/PR positive, HER2 negative, node-positive disease. It should not be used in patients with HER2 positive or triple-negative disease.
Breast Cancer Index
If a patient has ER/PR positive, HER2 negative, node-negative breast cancer, the Breast Cancer Index may be used to guide decisions on adjuvant systemic therapy. It should not be used in patients with ER/PR positive, HER2 negative, node-positive disease. It should not be used in patients with HER2 positive or triple negative breast cancer to guide decisions on adjuvant systemic therapy.
Urokinase Plasminogen Activator and Plasminogen Activator Inhibitor Type 1
If a patient has ER/PR positive, HER2 negative, node negative breast cancer, Urokinase Plasminogen Activator and Plasminogen Activator Inhibitor Type 1 may be used to guide decisions on adjuvant systemic therapy. It should not be used in patients with HER2 positive or triple negative breast cancer.
MammaPrint
If a patient has ER/PR positive, HER2 negative (node-positive or node-negative) breast cancer, the MammaPrint 70-gene assay should not be used to guide decisions on adjuvant systemic therapy. It should not be used in patients with HER2 positive disease. It should not be used in patients with triple negative breast cancer.
Mammostrat
If a patient has ER/PR positive, HER2 negative (node-positive or node-negative) breast cancer, the Mammostrat 5-protein assay should not be used to guide decisions on adjuvant systemic therapy. It should not be used in patients with HER2 positive or triple negative breast cancer.
Immunohistochemistry 4
If a patient has ER/PR positive, HER2 negative (node-positive or node-negative) breast cancer, Immunohistochemistry 4 (IHC4) should not be used to guide decisions on adjuvant systemic chemotherapy. It should not be used in patients with HER2 positive or triple negative breast cancer.
Circulating Tumor Cells
The clinician should not use circulating tumor cells to guide decisions on adjuvant systemic therapy.
Tumor-Infiltrating Lymphocytes
If a patient has ER/PR positive, HER2 negative (node-positive or node-negative) breast cancer, Tumor-Infiltrating Lymphocytes should not be used for decision making. It should not be used in patients with HER2 positive or triple negative breast cancer.
Protein Encoded by MKI67 Gene
Protein encoded by the MKI67 gene labeling index by IHC should not be used to guide choice on adjuvant chemotherapy.
Extended Endocrine Therapy
If a patient has ER/PR positive, HER2 negative (node-negative) breast cancer and has had 5 years of endocrine therapy without evidence of recurrence, multiparameter gene expression or protein assays (Oncotype DX, EndoPredict, PAM50, Breast Cancer Index, or IHC4) should not be used to guide decisions on extended endocrine therapy.
The Clinical Question 2 will be addressed in the eNL edition (Part 2) next week.
Harris LN, Ismaila N, McShane LM, et al: Use of biomarkers to guide decisions on adjuvant systemic therapy for women with early-stage invasive breast cancer: American Society of Clinical Oncology clinical practice guideline. J Clin Oncol 2016;34:1134-1150.
