Breast cancer specific mortality in patients with early-stage hormone receptor-positive invasive breast cancer and oncotype DX recurrence score results in the SEER database.

176 Background: NCI's SEER Program provides cancer incidence and survival statistics for ~28% of the US. New research models are needed to characterize the use and impact of genomic tests on patient outcomes. Genomic Health and SEER collaborated to electronically supplement SEER registries with Recurrence Score (RS) results, and have evaluated breast cancer specific mortality (BCSM) in early stage hormone receptor (HR)+ HER2- invasive breast cancer.

METHODS: Pts were eligible for pre-specified node negative (N-) disease analysis if HR+, HER2- (by RT-PCR), no prior malignancy, 40-85 years of age, and diagnosed between Jan 2004 (Oncotype DX available Jan 2004) and Dec 2011 (SEER survival analysis complete through 2012). BCSM was defined as previously described (Howlader et al, JNCI 2010). Additional analyses of BCSM were performed for pts with N+ disease.

RESULTS: Of 169,158 eligible N- pts, 38,568 (23%) had a RS, increasing from 2% in 2004 to 35% in 2011. Pts with RS had median age of 57yr, were 99.4% female, 84% white, 29% grade 1 & 54% grade 2, 25% < 1cm & 53% 1-2cm. Median FU was 39mo. 8,239 pts had > 5yrs follow-up. Among RS < 18 (N = 21,023), RS 18-30 (N = 14,494) and RS ≥ 31 (N = 3,051) pts, chemotherapy use was reported in 7%, 34%, & 69%, respectively, and 5yr N- BCSM was 0.4% (95% CI, 0.3-0.6), 1.4% (95% CI, 1.1-1.7) and 4.4% (95% CI,3.4-5.6), respectively. Multivariate showed that RS was significantly associated with BCSM after adjusting for age, grade, and tumor size (p < 0.001), and when stratified by treatment (p < 0.001). BCSM results in additional N- subgroups (e.g., socioeconomic), and in > 60,000 N+ pts will be presented.

CONCLUSIONS: 5yr survival outcomes are excellent in the over 21,000 N- pts with RS < 18 disease. RS ≥ 31 disease is associated with greater 5yr mortality despite addition of chemotherapy. The large sample size of this population-based observational study provides important information on prospective outcomes in subsets of pts that are often underrepresented in randomized clinical trials.