Cancer is a heterogeneous disease, which is based on an intricate network of processes at different spatiotemporal scales, from the genome to the tissue level. Hence the necessity for the biomedical and pharmaceutical research to work in a multiscale fashion. In this respect, a significant help derives from the collaboration with theoretical sciences. Indeed, mathematical models can provide insights into tumor-related processes and support clinical oncologists in the design of treatment regime, dosage, schedule and toxicity.