150PD - Breast cancer-specific survival in >4,600 patients with lymph node-positive (LN+) hormone receptor-positive (HR+) invasive breast cancer (BC) and 21-gene recurrence score® (RS) results in the SEER registries

Abstract

The 21-gene RS assay has been shown to predict BC recurrence and adjuvant chemotherapy benefit in LN +, HR +, HER2-negative BC. We assessed 5-year BC-specific survival (BCSS) in LN+ patients with 21-gene RS results in the SEER registries, a cancer surveillance program that covers 30% of the US population. All SEER BC cases diagnosed 2004-2012 were linked to 21-gene assays performed by the Genomic Health Clinical Laboratory. The analysis was restricted to single primary invasive BC, LN +, no distant metastases, HR+ (per SEER), HER2-negative (per RT-PCR). Using the actuarial method in SEER*Stat, BCSS was assessed for those who were diagnosed 2004-2011 with survival follow-up through 2012, by RS category and by number of positive nodes. The proportion of women with LN +, HR+ BC who had RS results (n = 7695) increased over time between 2004 (0.3%, n = 33) and 2012 (13.8%, n = 2010), and was lower with increasing nodal involvement, from micrometastases only (36.0%, n = 792) to 4+ nodes (2.6%, n = 81) in 2012. BCSS differed significantly by both RS category (log-rank p < 0.001) and number of positive nodes (p < 0.001). Five-year BCSS outcomes for those with RS <18 ranged from 99.4% (95% CI, 97.4%-99.9%) in those with micrometastases to 85.7% (95% CI, 33.4%-97.9%) in those with 4+ nodes. Similar patterns were found for those with RS 18-30 and RS ≥31 (Table).Tabled 1RS <18RS 18-30RS ≥31# of positive LNN5-y BCSS (95% CI)N5-y BCSS (95% CI)N5-y BCSS (95% CI)Micromets only120799.4 (97.4-99.9)73299.3 (98.2-99.7)13584.2 (69.2-92.2)1108499.2 (97.2-99.8)67596.3 (91.8-98.4)13591.3 (79.5-96.4)230097.9 (92.7-99.4)19296.0 (84.6-99.0)3673.2 (20.4-94.1)310394.7 (77.4-98.9)7094.0 (75.9-98.6)2285.4 (51.6-96.3)4+8285.7 (33.4-97.9)9379.5 (58.0-90.8)3175.1 (39.2-91.6) Open table in a new tab Overall, 5-year BCSS is excellent in patients with RS <18 and few positive nodes and worsens with increasing number of involved lymph nodes and with higher RS. Updated data with longer follow-up is will be presented.