Here, based on previous data pointing towards a prognostic role of SAMHD1 in BC [30], we describe the use of SAMHD1 expression in tumor biopsies post-surgery as a novel prognostic biomarker in early BC patients with residual disease after NACT, where there is still the need to develop effective biomarkers and more efficient alternative treatment options. This evidence concerns the gene SAMHD1 and breast cancer.