Samuel F. Bakhoum, MD, PhD, Memorial Sloan Kettering Cancer Center, New York, NY, discusses chromosomal instability in the field of tumor evolution, and highlights the extent of chromosomal abnormalities in cancer. Dr Bakhoum touches on the advent of next-generation sequencing and how this has led to a greater appreciation of large-scale chromosomal abnormalities as an important aspect of tumor evolution. This interview took place at the virtual American Association for Cancer Research (AACR) Annual Meeting 2021.