Key clinical point: Among women with breast cancer and high clinical risk, a subgroup of patients with low genomic risk identified by the 70-gene signature showed excellent distant metastasis-free survival (DMFS) even without chemotherapy. No benefits of chemotherapy were observed in women older than 50 years.
Major finding: Eight-year DMFS in patients with high clinical but low genomic risk with vs. without chemotherapy was 92.0% vs. 89.4%, with the benefit of adding chemotherapy to endocrine therapy remaining small (absolute difference, 2·6 percentage points). Chemotherapy showed no benefits in older women aged more than 50 years (absolute difference, 0.2 percentage points).
Study details : Findings are from the 8-year analysis of phase 3 MINDACT trial, including women with primary nonmetastatic invasive breast cancer with up to 3 positive lymph nodes. The 70-gene signature (MammaPrint) identified women with high clinical but low genomic risk who were randomly assigned to chemotherapy (n=749) vs. no chemotherapy (n=748).
Disclosures: This study was funded by European Commission Sixth Framework Programme (ECSFP). Some investigators including the lead author reported ties with various pharmaceutical companies and funding agencies including the ECSFP.
Source: Piccart M et al. Lancet Oncol. 2021 Mar 12. doi: 10.1016/S1470-2045(21)00007-3 .