Interestingly, an increased risk of disease progression or death was observed in patients with ≥4 IGF-1R negative CTCs; this was the largest prospective observation so far, evaluating the prognostic role of IGF1-R expression on CTCs in BC patients and these results support further evaluation of the role of IGF-1R on CTCs to improve patient stratification and to implement new targeted strategies. The gene discussed is IGF1R; the disease is breast cancer.