Since cancer is a complex phenomenon that incorporates events occurring on different
length and time scales, therefore multiscale models are needed if we hope to adequately address
cancer specific questions. In this paper we present three different multiscale individual-cell-based
models, each motivated by cancer-related problems emerging from each of the spatial scales: extracellular,
cellular or subcellular, but also incorporating relevant information from other levels.
We apply these hybrid models to investigate the influence of the microenvironement on tumour
invasion, cell-cell collaboration and competition leading to the initiation and growth of epithelial
tumours, and to evolution of cell phenotypes/genotypes arising in tumours growing in different
oxygen concentrations. We also discuss how these models relate to one another and can be used to
bridge biological scales relevant to cancer.