Use of a 21-gene reverse transcriptase-polymerase chain reaction (RT-PCR) assay to guide therapy in 14 Michigan Breast Oncology Quality Initiative (MiBOQI) sites.

Abstract

6039 Background: A 21-gene RT-PCR assay (the assay) has been recommended to predict the risk of recurrence and likelihood of adjuvant chemotherapy (AC) benefit in a subgroup of newly diagnosed patients with breast cancer (BC) in National Comprehensive Cancer Network guidelines (NCCN GLs) since 2008. MiBOQI, a statewide quality improvement initiative, used the NCCN BC Outcome Database Project (BCOD) model to determine the extent and appropriateness of assay use and impact of recurrence scores (RS) on AC use. Methods: 4,594 women diagnosed with unilateral breast cancer with completed follow-up were enrolled between November 2006 and June 2009 from 14 sites. The BCOD prospectively collects data on newly diagnosed BC including the results of gene expression analysis. The NCCN BC GL considers the assay an appropriate option when evaluating BC primary tumors as 0.6-1.0 cm with unfavorable features or > 1 cm, and node-negative, hormone receptor-positive and HER2-negative. Results: 471 out of 1,458 (32%) women appropriately had the assay. 90% of those were < 70 years old and 53% had a low RS, 37% an intermediate RS, and 9% a high RS. In women < 70 with appropriate characteristics (n = 1,035), 36% who received the assay had AC, while 44% who did not have the assay received AC (p = 0.006). 31/217 (14%) with low RS, 79/152 (52%) with intermediate RS, and 33/37 (89%) with high RS received AC (p < 0.001 between RS groups). For women < 70 who had at least one characteristic not consistent with NCCN GL recommended assay use, 142/2,289 (6%) received the assay. Among patients < 70 who were otherwise appropriate assay candidates, those with HER2-positivity and those with tumors < 0.6 cm or 0.6-1.0 cm with no unfavorable features had assay use rates of 17% (95% CI, 12-25%) and 18% (95% CI, 14-22%). Conclusions: The 21-gene RT-PCR assay is frequently used in an appropriate group of women with BC. Those who receive the test have a significant reduction in the use of AC. HER2-positivity and small tumors were associated with nonconcordant assay use. The assay guided use of AC, but 14% and 11% of patients in low and high RS groups had nonconcordant use of AC. Author Disclosure Employment or Leadership Position Consultant or Advisory Role Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration American Society of Clinical Oncology, BlueCross Blue Shield of MI, National Comprehensive Cancer Network Genomic Health Genomic Health BlueCross BlueShield of MI, BlueCross BlueShield of Michigan, National Comprehensive Cancer Network