What does the term "tumor heterogeneity" refer to?

Tumor heterogeneity refers to the diversity of cell populations within a tumor. This concept highlights that tumors are not composed of a single type of cell but rather consist of a mixture of different cells that can vary in terms of genetic makeup, phenotype, and behavior. This diversity can arise from several factors including mutations that accumulate over time, the microenvironment of the tumor, and variations in the cell lineages.

Understanding tumor heterogeneity is crucial for effective cancer treatment because this variation can lead to differential responses to therapies. Some cells within a tumor may be more resistant to treatment than others, which can result in treatment failure and disease progression. Consequently, recognizing and addressing this complexity is key in the development of personalized medicine approaches to treat cancer more effectively.