A comparison of 12-gene colon cancer assay gene expression in African American and Caucasian patients with stage II colon cancer.

BACKGROUND: African American (AA) colon cancer patients have a worse prognosis than Caucasian (CA) colon cancer patients, however, reasons for this disparity are not well understood. To determine if tumor biology might contribute to differential prognosis, we measured recurrence risk and gene expression using the Oncotype DX® Colon Cancer Assay (12-gene assay) and compared the Recurrence Score results and gene expression profiles between AA patients and CA patients with stage II colon cancer. METHODS: We retrieved demographic, clinical, and archived tumor tissues from stage II colon cancer patients at four institutions. The 12-gene assay and mismatch repair (MMR) status were performed by Genomic Health (Redwood City, California). Student's t-test and the Wilcoxon rank sum test were used to compare Recurrence Score data and gene expression data from AA and CA patients (SAS Enterprise Guide 5.1). RESULTS: Samples from 122 AA and 122 CA patients were analyzed. There were 118 women (63 AA, 55 CA) and 126 men (59 AA, 67 CA). Median age was 66 years for AA patients and 68 for CA patients. Age, gender, year of surgery, pathologic T-stage, tumor location, the number of lymph nodes examined, lymphovascular invasion, and MMR status were not significantly different between groups (p = 0.93). The mean Recurrence Score result for AA patients (27.9 ± 12.8) and CA patients (28.1 ± 11.8) was not significantly different and the proportions of patients with high Recurrence Score values (≥41) were similar between the groups (17/122 AA; 15/122 CA). None of the gene expression variables, either single genes or gene groups (cell cycle group, stromal group, BGN1, FAP, INHBA1, Ki67, MYBL2, cMYC and GADD45B), was significantly different between the racial groups. After controlling for clinical and pathologic covariates, the means and distributions of Recurrence Score results and gene expression profiles showed no statistically significant difference between patient groups. CONCLUSION: The distribution of Recurrence Score results and gene expression data was similar in a cohort of AA and CA patients with stage II colon cancer and similar clinical characteristics, suggesting that tumor biology, as represented by the 12-gene assay, did not differ between patient groups.

The impact of a genomic assay (Oncotype DX) on adjuvant treatment recommendations in early breast cancer.

OBJECTIVES: To assess how the recurrence score of the Oncotype DX breast cancer assay influences adjuvant systemic treatment decisions in the multidisciplinary meeting (MDM) for patients with early breast cancer (EBC) in Australia. DESIGN, SETTING AND PARTICIPANTS: A before-and-after study at three academic medical centres in Melbourne with patients and physicians serving as their own controls. Paired systemic adjuvant treatment recommendations were made in multidisciplinary meetings (MDMs) before and after Oncotype DX testing. Medical oncologists and surgeons, treating patients with unifocal, hormone receptor-positive, human epidermal growth factor receptor 2-negative, node-negative or node-positive early breast cancer. MAIN OUTCOME MEASURES: Changes in physician treatment recommendations. RESULTS: This study enrolled 151 eligible patients between 1 November 2010 and 30 September 2011. Of these, 101 patients (67%) had node-negative and 50 (33%) had node-positive tumours. Recurrence score information resulted in treatment recommendation changes for 24 patients with node-negative tumours (24%) and for 13 patients with node-positive tumours (26%). The proportional change from chemo-hormonal therapy (CHT) to hormonal therapy (HT) was significantly greater than from HT to CHT for patients with node-negative tumours (23% difference in proportions; P= 0.02), and of similar magnitude for patients with node-positive tumours (25% difference in proportions; P = 0.14). CONCLUSION: The Oncotype DX recurrence score has a major impact on adjuvant treatment decision making in the MDM setting.