Tumour heterogeneity

Tumour heterogeneity is when cancer cells inside a tumour are different from each other. Think of it like a family of different kinds of animals living in a zoo. Each animal in the family looks and behaves differently from the other animals - same goes for the cancer cells inside a tumour. Because the cells are different, doctors have a hard time treating the tumour as one thing. They need to look at each cell type differently in order to figure out how to treat the tumour.