Additional prognostic value of the 70-gene signature (MammaPrint^®) among breast cancer patients with 4-9 positive lymph nodes

Background: The 70 gene-signature (MammaPrint^®) is a prognostic profile of distant recurrence and survival of primary breast cancer (BC). BC patients with 4-9 positive nodes (LN 4-9) are considered clinically at high-risk. Herein we examined MammaPrint^® added prognostic value in this group. Patients and methods: MammaPrint^® profiles were generated from frozen tumours of patients operated from primary BC. Samples were classified as genomic Low Risk (GLR) or genomic High Risk (GHR). Results: Among the 173 samples, 70 (40%) were classified as GLR and 103 (60%) as GHR. Tumours in the GHR group were significantly more often ductal carcinomas (93%), grade 3 (60%), oestrogen and progesterone-negative, Her2 positive (25%). In the GLR category, the 5-year overall survival was 97% vs. 76% for in the GHR group ( p<0.01); Distant Metastasis Free Survival (DMFS) at 5 years was 87% for GLR patients and 63% for GHR patients ( p<0.01). In the Luminal A subgroup, the genomic profile was the only independent risk factor for DM and BC specific death. Conclusion: In the Luminal A subgroup, MammaPrint^® is an independent prognostic marker in BC patients with LN 4-9 and may be integrated in a selection strategy of patients candidate for more aggressive therapeutic approaches.