Mitosis is essential for the division and increasing of cells. Since in many cancers, this has gone “wild” and these cancerous cells grow and rob the body of nutrients which helps them grow yet even more; to slow or stop mitosis - especially in cancerous cells, gives the body a chance to fight back, before they are overwhelmed by cancerous growth.
Think this? A society organized for the purpose of waging war. Sparta became a state because they were scarred by the emerging threat of a helot revolt.