Among these experimental tracers, the most promising for breast cancer assessment are 16α‐18F‐fluoroestradiol (18F‐FES), 89Zr‐trastuzumab, choline derivates, 3‐deoxy‐3‐[18F]fluorothymidine (18F‐FLT), and, recently, 68(Ga)‐FAP inhibitor (FAPI)‐46.43 The gene discussed is FAP; the disease is breast carcinoma.