Abstract: A therapeutic combination of a compound having antiestrogenic activity and a CDK4/6 inhibitor is used in a method for the treatment of BC or other estrogen-responsive tumors in a human patient, wherein the method comprises subjecting the patient to a fasting mimicking diet for a period of 24-190 hours while the patient is being treated with the therapeutic combination, in which the compound having antiestrogenic activity can be a selective estrogen receptor modulator (SERM), a selective estrogen receptor degrader (SERD) or an aromatase inhibitor (AI).