Nanoparticles made of different materials, which can be used to diagnose, visualize, and simultaneously fight a cancerous tumor, were the core theme at the international seminar on Current Trends in Cancer Theranostics (CTCT-2016). This seminar, which was held for the second time, was organized jointly by the National Cancer Institute, Vilnius University in Lithuania, and the Leibniz Institute of Photonic Technology (IPHT) Jena.