In patients, significant differences were not observed between mifepristone levels after 1 or 2 weeks of treatment (day 7 (mean ± s.d.): 300.3 ± 31.7 ng/mL (690 ± 72.9 nmol/L); day 14: 320 ± 54.3 ng/mL (745 ± 126.4 nmol/L; n = 11); (Elia et al. 2022)), and they were more than twenty times higher than those observed in the animal model using mifepristone pellets (P < 0.001),suggesting that the effect of lower mifepristone doses in breast cancer patients with higher levels of PRA than PRB should be tested. This evidence concerns the gene RB1 and breast cancer.