ESR1 and breast cancer: To assess the degree of sensitivity of the model’s predictive accuracy and the model’s calibration to the ER/PR status of the patient population, we considered the following six scenarios of BC patients: scenario 1: stage I, ER/PR+; scenario 2: stage II, ER/PR+; scenario 3: stage III, ER/PR+; scenario 4: stage I, ER/PR−; scenario 5: stage II, ER/PR−; and Scenario 6: stage III, ER/PR−.