The multicellular organism and cancer

Cancer is a disease of multicellular organisms in which, following the manifestation of genetic alterations, one neoplastic cell develops into a tumour mass which grows escaping all the normal rules of cell coexistence which regulates multicellular organisms. We define as malignant tumour one which spreads throughout the body forming metastases, and as benign tumour one which is localized and non-invasive. Cancer is found mostly throughout the Metazoa (i.e. multicellular animals) but is also present in some plants. A simpler neoplastic-like behaviour, so-called cheating, is present instead even in the simplest multicellular bacterial organisms, where cells can start to grow excessively, escaping normal behaviour.