Life is the most complex and diverse physical system in the known universe. It is remarkable that underlying that complexity it is possible to find simple scaling laws in many biological processes over a wide range of spatial and temporal scales. Many processes in biology obey scaling laws: metabolic rates, lengths of genomes, tree heights, concentrations of RNA, masses of cerebral gray matter, density of mitochondria and life spans, etc. We study scaling laws in cancer to find regularities behind the observed phenomena (metabolism, growth rates, etc.) and define metrics of cancer aggressiveness that have utility as prognostic and response biomarkers.