ESR1 and cancer: The 8th edition of the American Joint Commission on Cancer (AJCC) Cancer Staging manual59 determined it was appropriate to incorporate the ODXRS into staging for the subgroup of invasive breast carcinoma patients defined by Arm A of the TAILORx study,60 which includes ER+, HER‐2 negative, LN‐negative tumors that are 1.1‐5.0 cm in size (or 0.6‐1.0 cm with intermediate or high histologic or nuclear grade), and have an ODXRS <11.