title: Is the Oncotype DX assay necessary in strongly estrogen receptor-positive breast cancers?
abstract: The 21-gene Oncotype DX recurrence score (RS) assay quantifies risk of distant recurrence and predicts benefit from chemotherapy in tamoxifen-treated estrogen receptor (ER)-positive, node-negative breast cancer. Although clinically useful, the assay costs roughly $4650. Because  the assay is weighted heavily towards expression of ER, our objective was to determine its clinical utility in strongly ER-positive tumors. This was a retrospective study of Huntington Hospital patients undergoing an Oncotype DX assay between 2007 and 2010. Data collected included patient  age, expression of ER, progesterone receptor (PR), HER2/neu, ki67, and p53, tumor size, node status, lymphovascular invasion, and nuclear grade. Of 133 total patients, 84 (63.2%) had strongly ER-positive tumors (≥90% expression). Only seven of 84 patients (8.3%) had a high risk RS (>30),  indicating statistically significant predicted benefit from chemotherapy. All seven had intermediate to high ki67 expression (>20%) and lower PR expression (≤50%). Our study demonstrates that the clinical utility of the Oncotype DX assay in these patients is limited as most patients  with strongly ER-positive tumors will have a low or intermediate RS. Future studies are needed to identify additional predictive factors in these patients with otherwise good prognosis.
authors: Department of Surgery, Huntington Hospital, Pasadena, California, USA.
authors: Jenny J
authors: JJ
authors: Lee
authors: Jeannie
authors: J
authors: Shen
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000378:metabolism; D001943:Breast Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism*; D004273:DNA, Neoplasm / Q000235:genetics; D004965:Estrogen Antagonists / Q000627:therapeutic use; D005260:Female; D005500:Follow-Up Studies; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D018734:Genes, erbB-2 / Q000235:genetics*; D006801:Humans; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local; D009367:Neoplasm Staging; D011379:Prognosis; D011960:Receptors, Estrogen / Q000187:drug effects / Q000378:metabolism*; D012189:Retrospective Studies; D013629:Tamoxifen / Q000627:therapeutic use
chemical_list: D014408:Biomarkers, Tumor; D004273:DNA, Neoplasm; D004965:Estrogen Antagonists; D011960:Receptors, Estrogen; D013629:Tamoxifen