Cellular response to injury can include adaptation, injury, or disease. Adaptation represents a new abnormal state where cells maintain viability and homeostasis in response to stress. Key types of cellular adaptation include hyperplasia (increased cell number), hypertrophy (increased cell size), atrophy (decreased cell size and number), and metaplasia (one cell type replaces another). While adaptation allows cell survival, the underlying stresses that cause adaptation could also promote cancer if persistent over time.