ESR1 and neoplasm: In the P024, IMPACT and POL trials, patients with modified PEPI score of 0 were all ER+ (Allred score 3–8) because ER Allred score 0–2 post aromatase inhibitor or tamoxifen treatment was associated with either a high Ki-67 or high tumor staging (or both) excluding these cases from PEPI-0 status without the need for information on ER.