Piccart M, van't Veer LJ, Poncet C, et al. - Given that patients with breast cancer of high clinical and low genomic risk who did not receive chemotherapy exhibited excellent 5-year distant metastasis-free survival of 94.7% in the MINDACT trial (a multicenter, randomized, phase 3 trial in nine European countries), researchers here report long-term follow-up outcomes combined with an exploratory study according to age. Participants were those with histologically verified primary invasive breast cancer (stage T1, T2, or operable T3), among other criteria, in whom genomic risk (employing the MammaPrint 70-gene signature) as well as clinical risk (with a modified version of Adjuvant! Online) were assessed. A follow-up approaching 9 years revealed an intact ability of the 70-gene signature to detect a subgroup, among females with high clinical risk, characterized by a low genomic risk and an excellent distant metastasis-free survival resulting from endocrine therapy alone. For these females, the degree of the advantage from the addition of chemotherapy to endocrine therapy continued to be small (2.6 percentage points), with no enhancement by nodal positivity. This advantage seemed to be age-dependent in an underpowered exploratory analysis, as it was only evident in females younger than 50 years where it reached a clinically meaningful threshold of 5 percentage points. Although, likely because of ovarian function suppression by chemotherapy, it deserves to be a component of informed, shared decision making. Further inquiry is necessary in younger females, who might require reinforced endocrine therapy to forego chemotherapy.