Cancer is one of the deadly diseases threatening human lives. Although there are many therapeutic modalities available for treating various types of cancers, each method has its own limitations and problems, which diminish the efficacies and the outcomes of medical treatments. Nanomaterials have many unique properties different from their macro-scale counterparts.  In this talk, I will present examples of using nanomaterials and nanotechnology to help conquer some medical issues and problems and improve the therapeutic efficacies of photothermal therapy, photodynamic therapy, boron neutron capture therapy (BNCT), and chemotherapy.  Medical problems in the treatments of tumors will be discussed, including light penetration in biological tissues, tumor hypoxia problem, multidrug resistance problem, how to deliver large amounts of boron atoms to tumor sites for effective BNCT treatment, etc.