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. 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 recommendations are meant to provide guidance to the Health Care Provider, as appropriate treatment is considered for patients with newly diagnosed, early-stage invasive breast cancer.
Two important questions were addressed by these guidelines – The Part I edition last week (www.oncoprescribe.com) addressed the first clinical question. This week’s edition (Part II) addresses the second clinical question.
Clinical Question 2: For women with early-stage invasive breast cancer and with known estrogen receptor/progesterone receptor and HER2 status, which additional biomarkers have demonstrated clinical utility to guide the choice of specific drugs or regimens for adjuvant systemic therapy?
Tamoxifen
CYP2D6 polymorphisms should not be used to guide adjuvant endocrine therapy selection. The expression of p27 by IHC should not be used to guide adjuvant endocrine therapy selection.
Aromatase Inhibitors
Protein encoded by the MKI67 gene labeling index by IHC should not be used to guide adjuvant endocrine therapy.
Taxanes
Microtubule-associated protein Tau mRNA expression or mRNA expression by IHC should not be used to guide adjuvant chemotherapy selection. HER1/Epidermal Growth Factor Receptor expression by IHC should not be used to guide adjuvant chemotherapy selection.
Anthracyclines
TOP2A gene amplification or TOP2A protein expression by IHC should not be used to guide adjuvant chemotherapy selection. HER2 and TOP2A gene coamplification, CEP17 duplication, TIMP-1, FOXP3, or p53 should not be used to guide adjuvant chemotherapy selection.
Trastuzumab
If a patient has HER2 positive breast cancer, PTEN should not be used to guide adjuvant therapy selection. If a patient has HER2 positive breast cancer, soluble HER2 levels should not be used to guide the selection of the type of adjuvant therapy.
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.
