<unk>  can be viewed through the lens of natural<unk> . The animal host's body is the environment which applies the selective pressures upon<unk>  cells. The most fit<unk>  cells will have traits that will allow them to out compete other<unk>  cells which they are related to, but are genetically different from. This genetic diversity of cells within a tumor gives<unk>  an evolutionary advantage over the host's ability to inhibit and destroy tumors. Therefore, other selective pressures such as clinical treatments and pharmaceutical treatments are needed to help destroy the large amount of genetically diverse<unk> ous cells within a tumor. It is because of the high genetic diversity between<unk>  cells within a tumor that makes<unk>  a formidable foe for the survival of animal hosts. It has also been proposed that<unk>  is a selective force that has driven the evolution of animals. Therefore,<unk>  and animals have been paired as competitors in co-evolution throughout time.
Cancer selection
Sex selection
Dynamic mutation
Antineoplastic resistance
Gender transitioning
Tumor initiation
Tumor progression
Graft-versus-tumor effect