Chromosomal instability is a phenomenon present in most cancers and characterized by the gain or loss of chromosomes as well as structural changes in these chromosomes. This instability results in a somatic alteration of the number of copies which would be the necessary basis for the evolution of the tumor.
In an international study by researchers from the Francis Crick Institute (United Kingdom) and the Max Delbrück Center for Molecular Medicine (Germany) and in which researchers from Gustave Roussy collaborated, the authors observed that tumors are constantly changing throughout throughout its development. It would also seem that the order of modifications is dictated by precise rules governing the evolution. The analyzes which made it possible to reach these conclusions concerned 1421 samples from 394 tumors and representing 22 types of tumours. The results are published in the journal Nature on September 2, 2020.
Analyzes have indeed revealed that in different types of cancer, tumor cells are subject to the same chromosomal events at different stages of their development; some mutations were common early in tumor development while others were more likely to appear at later stages. The study further shows that different subclones in the same tumor independently acquired the same types of chromosomal changes (somatic alterations), a parallel cell evolution present in 37% of the tumors analyzed. These observations suggest that the evolution of a tumor must respect obligatory passage points. The identification of these stages and the knowledge of the rules governing the evolution of tumors could make it possible to predict them and thus put in place new therapeutic strategies.
Watkins, T.B.K., Lim, E.L., Petkovic, M. et al. Pervasive chromosomal instability and karyotype order in tumour evolution. Nature (2020). https://doi.org/10.1038/s41586-020-2698-6