Retinoid-like compounds which act as agonists of the RXR retinoid receptor sites induce apoptosis of tumor cells in cell cultures, and are used as drugs to treat tumors in mammals including humans. Compounds which are specific agonists of RXR receptors and also compounds which are agonists of both RAR and RXR agonist (pan-agonists) induce apoptosis, although the RXR agonist compounds are preferred as drugs to avoid undesirable side effects associated with RAR agonist activity. The RXR agonists compounds are administered to mammals afflicted with tumors in pharmaceutical compositions adapted for systemic topical or for intralesional administration. The range of concentration of the active ingredient RXR agonist compound in the pharmaceutical compositions is approximately between 0.001 and 5 percent by weight, and such that the composition delivers approximately 0.1 mg to 100 mg of the active ingredient per kg body weight of the patient, per day of treatment.