The cells of the higher eukaryotes are usually not replicating their deoxyribonucleic acid (DNA). It is because they are either in a resting phase of the cell cycle or have ceased dividing entirely.
When double-strand breaks occur in cells where undamaged strands or sister chromatids are not present, these ends must be repaired, either perfectly or imperfectly.
The broken ends can initiate potentially harmful chromosomal rearrangements that could lead to a cancerous state.