Quantitative and qualitative methods for measuring chromosomal instability in tumor cells

To preserve cellular and tissue homeostasis, cells must maintain a coordinated network of molecular mechanisms that ensure accurate chromosome segregation during mitosis. Errors in this process, such as chromosome mis-segregation, lagging chromosomes in anaphase, centrosome amplification, or chromosome breaks generating non-homologous fusions and dicentric chromosomes, can lead to chromosomal instability (CIN). Persistent CIN promotes chromosomal abnormalities, driving tumor cell proliferation, intratumoral genomic diversity, and ultimately tumor initiation and progression. Tumors exhibiting CIN, characterized by aneuploidy or large-scale structural rearrangements, are strongly associated with metastasis, angiogenesis, and chemoresistance. Despite its biological and clinical relevance, methods to detect, quantify, and evaluate CIN remain poorly standardized. In this work, we critically reviewed the scientific literature to compile and discuss the principal quantitative and qualitative strategies currently available for measuring CIN in vitro.