In this brief survey, various aspects of cancer complexity and how this complexity can
be confronted using modern complex networks’ theory and gene expression datasets, are described.
In particular, the causes and the basic features of cancer complexity, as well as the challenges
it brought are underlined, while the importance of gene expression data in cancer research
and in reverse engineering of gene co-expression networks is highlighted. In addition, an introduction
to the corresponding theoretical and mathematical framework of graph theory and complex
networks is provided. The basics of network reconstruction along with the limitations of gene
network inference, the enrichment and survival analysis, evolution, robustness-resilience and cascades
in complex networks, are described. Finally, an indicative and suggestive example of a cancer
gene co-expression network inference and analysis is given.