Figure 3.

The progressive transformation of natural cells into cancer cells. This schema shows the dichotomous generation of a cancer cell as a distinct entity (a) or with a number of functions shared with a natural cell. The area of the intersection is proportional to the number of shared properties: a zero area indicates that the cancer cell is a wholly distinct entity, whereas its progressive but time-limited reduction leads to a cell that has a proportion of shared behaviours and a proportion of distinct properties that determine its tumoural nature i.e. tumour growth, invasiveness, metastatic potential and responsiveness or resistance to therapy (b).