According to the ASTRO, application of IORT as APBI can be considered for women at the age of ≥ 50 years with unicentric, pT1, pN0, nonlobular invasive breast cancer, positive estrogen receptor status, negative margins by at least 2 mm as well as DCIS when meeting specific criteria [14]. The gene discussed is ESR1; the disease is invasive breast carcinoma.