Our present findings indicate that combination doxorubicin-high dose FO/Se treatment results in greater inhibition of Ki-67, cyclin D1/CDK4/CDK6, cyclin E/CDK2, and cancer stem cells markers in tumor tissues, suggesting that FO/Se increases the effectiveness of doxorubicin treatment by arresting cancer growth and inhibiting cancer stemness. The gene discussed is CDK4; the disease is neoplasm.