Sustained pro-proliferative signaling is one of the hallmarks of cancer. Although it is generally understood that the oncogenic signaling pathways are overactivated, or at least abnormally activated, in cancer cells, important mechanistic details of such abnormal activation remain unresolved. Among these details are such aspects of signaling as robustness, redundancy, signal amplification, and others, which touch upon the domain of information theory - the field of mathematics and engineering dealing with properties of information storage, encoding, and transmission. Information theory only recently has started to be applied to intracellular signaling. Here, we overview the recent advances provided by the information theory, focusing on the nuclear factor (NF)-κB, extracellular signal-regulated kinase (ERK), and G-protein-coupled receptor (GPCR) pathways, which are frequently hijacked in cancer. Furthermore, we show how viewing previously untouched mechanics of oncogenic signaling through information theory applications may evolve into novel ways of anticancer drug discovery.