Breast cancer-specific survival in patients with lymph node-positive hormone receptor-positive invasive breast cancer and Oncotype DX Recurrence Score results in the SEER database

Megan C. Roberts, Dave P. Miller, Steven Shak, Valentina I. Petkov

The Oncotype DX(®) Breast Recurrence Score™ (RS) assay is validated to predict breast cancer (BC) recurrence and adjuvant chemotherapy benefit in select patients with lymph node-positive (LN+), hormone receptor-positive (HR+), HER2-negative BC. We assessed 5-year BC-specific survival (BCSS) in LN+ patients with RS results in SEER databases. In this population-based study, BC cases in SEER registries (diagnosed 2004-2013) were linked to RS results from assays performed by Genomic Health (2004-2014). The primary analysis included only patients (diagnosed 2004-2012) with LN+ (including micrometastases), HR+ (per SEER), and HER2-negative (per RT-PCR) primary invasive BC (N = 6768). BCSS, assessed by RS category and number of positive lymph nodes, was calculated using the actuarial method. The proportion of patients with RS results and LN+ disease (N = 8782) increased over time between 2004 and 2013, and decreased with increasing lymph node involvement from micrometastases to ≥4 lymph nodes. Five-year BCSS outcomes for those with RS < 18 ranged from 98.9% (95% CI 97.4-99.6) for those with micrometastases to 92.8% (95% CI 73.4-98.2) for those with ≥4 lymph nodes. Similar patterns were found for patients with RS 18-30 and RS ≥ 31. RS group was strongly predictive of BCSS among patients with micrometastases or up to three positive lymph nodes (p < 0.001). Overall, 5-year BCSS is excellent for patients with RS < 18 and micrometastases, one or two positive lymph nodes, and worsens with additionally involved lymph nodes. Further analyses should account for treatment variables, and longitudinal updates will be important to better characterize utilization of Oncotype DX testing and long-term survival outcomes.